Interprovider VPNs

 

Interprovider VPNs

Interprovider VPNs provide connectivity between separate ASs. This functionality might be used by a VPN customer who has connections to several different service providers, or different connections to the same service provider in different geographic regions, each of which has a different AS. Figure 1 illustrates the type of network topology used by an interprovider VPN.

Figure 1: Interprovider VPN Network Topology
Interprovider VPN Network Topology

The following sections describe the ways you can configure an interprovider VPN:

Linking VRF Tables Between Autonomous Systems

You can connect two separate ASs by simply linking the VPN routing and forwarding (VRF) table in the AS border router (ASBR) of one AS to the VRF table in the ASBR in the other AS. Each ASBR must include a VRF routing instance for each VPN configured in both service provider networks. You then configure an IP session between the two ASBRs. In effect, the ASBRs treat each other as customer edge (CE) routers.

Because of the complexity of the configuration, particularly with regard to scaling, this method is not recommended. The details of this configuration are not provided with documentation.

Configuring Next Generation Layer 3 VPNs Options A, B, and C

For next generation Layer 3 VPNs, the PE routers within an AS use multiprotocol external BGP (MP-EBGP) to distribute labeled VPN–Internet Protocol version 4 (IPv4) routes to an ASBR or to a route reflector of which the ASBR is a client. The ASBR uses multiprotocol external BGP (MP-EBGP) to distribute the labeled VPN-IPv4 routes to its peer ASBR in the neighboring AS. The peer ASBR then uses MP-IBGP to distribute labeled VPN-IPv4 routes to PE routers, or to a route reflector of which the PE routers are a client.

You can configure both unicast (Junos OS Release 9.5 and later) and multicast (Junos OS Release 12.1 and later) next generation Layer 3 VPNs across ASs. The Junos OS software supports next generation Layer 3 VPNs option A, option B, and option C:

  • Option A—This is simple though less scaleable interprovider VPN solution to the problem of providing VPN services to a customer that has different sites, not all of which can use the same service provider. In this implementation, the VPN routing and forwarding (VRF) table in the ASBR of one AS is linked to the VRF table in the ASBR in the other AS. Each ASBR must include a VRF instance for each VPN configured in both service provider networks. Then an IGP or BGP must be configured between the ASBRs.

  • Option B—For this interprovider VPN solution, the customer requires VPN services for different sites, yet the same service provider is not available for all of those sites. With option B, the ASBR routers keep all VPN-IPv4 routes in the routing information base (RIB), and the labels associated with the prefixes are kept in the forwarding information base (FIB). Because the RIB and FIB tables can take too much of the respective allocated memory, this solution is not very scalable for an interprovider VPN. If a transit service provider is used between service provider 1 and service provider 2, the transit service provider also has to keep all VPN-IPv4 routes in the RIB and the corresponding labels in the FIB. The ASBRs at the transit service provider have the same functionality as ASBRs at service provider 1 or service provider 2 in this solution. The PE routers within each AS use multiprotocol internal BGP (MP-IBGP) to distribute labeled VPN-IPv4 routes to an ASBR or to a route reflector of which the ASBR is a client. The ASBR uses MP-EBGP to distribute the labeled VPN-IPv4 routes to its peer ASBR router in the neighboring AS. The peer ASBR then uses MP-IBGP to distribute labeled VPN-IPv4 routes to PE routers, or to a route reflector of which the PE routers are a client.

  • Option C—For this interprovider VPN solution, the customer service provider depends on the VPN service provider to deliver a VPN transport service between the customer service provider’s points of presence (POPs) or regional networks. This functionality might be used by a VPN customer who has connections to several different service providers, or different connections to the same service provider in different geographic regions, each of which has a different AS number. For option C, only routes internal to the service provider networks are announced between ASBRs. This is achieved by using the family inet labeled-unicast statements in the IBGP and EBGP configuration on the PE routers. Labeled IPv4 (not VPN-IPv4) routes are exchanged by the ASBRs to support MPLS. An MP-EBGP session between the end PE routers is used for the announcement of VPN-IPv4 routes. In this manner, VPN connectivity is provided while keeping VPN-IPv4 routes out of the core network.

Configuring Multihop MP-EBGP Between AS Border Routers

In this type of interprovider VPN configuration, P routers do not need to store all the routes in all the VPNs. Only the PE routers must have all the VPN routes. The P routers simply forward traffic to the PE routers—they do not store or process any information about the packets’ destination. The connections between the AS border routers in separate ASs forward traffic between the ASs, much as a label-switched path (LSP) works.

The following are the basic steps you take to configure an interprovider VPN in this manner:

  1. Configure multihop EBGP redistribution of labeled VPN-IPv4 routes between the source and destination ASs.

  2. Configure EBGP to redistribute labeled IPv4 routes from its AS to neighboring ASs.

  3. Configure MPLS on the end PE routers of the VPNs.

Interprovider VPN Example—MP-EBGP Between ISP Peer Routers

In this example, all routes learned from the CE routers (or switches) are sent over both service provider networks as VPN-IPv4 routes. The routes are initially learned by the PE routers (Router B and Router E) from the CE routers (Router A and Router F) and are announced by the PE routers to the AS border routers (Router C and Router D). The AS border routers are then configured with an MP-EBGP session, enabling them to pass the VPN-IPv4 routes with each other. When an AS border router—Router C for example—learns VPN-IPv4 routes from an IBGP PE, the following events occur:

  1. Router C sets itself as the next hop for the route and creates a label for that route.

  2. Router C advertises the VPN-IPv4 route to PE Router D in AS 10045.

  3. Router D sets the next hop to itself, creates another label, and then forwards the label and the route to its IBGP PE router (Router E).

This example has scaling limitations because of restrictions on the number of labels each PE router needs to allocate at the AS border.

Figure 2 illustrates the network topology used in this VPN example.

Figure 2: Network Topology for the Interprovider VPN Example
Network Topology for the Interprovider
VPN Example

For configuration information see the following sections:

Configuration for Router A

Configure a family inet EBGP session with Router B and export the direct routes:

Configuration for Router B

Router A is configured as a CE router (using the routing-instances statement) in the configuration for Router B. Because they exchange VPN-IPv4 routes, Router D and Router C are configured as PE routers.

Configure Router B:

Configuration for Router C

In the BGP protocol configuration for Router C, include the keep all statement. When this statement is included, BGP must store every route learned through BGP.

When you configure keep all or keep none and the peers support route refresh, the local speaker sends a refresh message and performs an import evaluation. For these peers, the sessions do not restart. To determine if a peer supports refresh, check for Peer supports Refresh capability in the output of the show bgp neighbor command.

Caution

If you configure keep all or keep none and the peer does not support session restart, the associated BGP sessions are restarted (flapped).

Configure two BGP sessions (configure family inet-vpn on both sessions):

  • IBGP session to Router B (group to-ibgp in this example)

  • EBGP session to Router D (group to-ebgp-pe in this example)

Interface t3-0/2/0 is added at the [edit protocols mpls] hierarchy level, allowing BGP to announce routes with labels over the EBGP session.

Configure Router C:

Configuration for Router D

The configuration for Router D is almost identical to that of Router C:

Configuration for Router E

The configuration for Router E is very similar to the configuration for Router B:

Configuration for Router F

Configure Router F as a CE router; the configuration is similar to that for Router A:

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Interprovider VPN Example—Multihop MP-EBGP with P Routers

In this example, labeled IPv4 (not VPN-IPv4), routes are exchanged by the AS border routers (Router C and Router D) to provide MPLS connectivity between the PE routers. Router G and H are provider routers.

Figure 3 illustrates the network topology used in this VPN example.

Figure 3: Network Topology of Interprovider VPN Example—Multihop MP-EBGP
Network Topology of Interprovider
VPN Example—Multihop MP-EBGP

Only routes internal to the service provider networks should be announced between Router C and Router D. Configure this by including the family inet labeled-unicast statement in the IBGP and EBGP configuration on the PE routers. When you set

family inet labeled-unicast, the local router announces internal routes from inet.0 in the following manner:

  • If a label exists for the route, the local router creates a label, performs a swap, and announces the route from inet.0 with the label.

  • If a label does not exist for the route, the local router creates a label, performs a pop, and announces the route from inet.0 with the label.

Routes learned from the labeled-unicast session are placed into the inet.0 routing table.

In addition, you configure a multihop MP-EBGP session between the end PE routers (Router B and Router E). This additional MP-EBGP session allows the announcement of VPN-IPv4 routes, and allows you to maintain VPN connectivity while keeping VPN-IPv4 routes out of the core of the network.

For configuration information, see the following sections:

Configuration for Router A

The configuration for Router A in this example is identical to the configuration for Router A in Interprovider VPN Example—MP-EBGP Between ISP Peer Routers. See Interprovider VPN Example—MP-EBGP Between ISP Peer Routers

Configuration for Router B

Router A is configured as a CE router (using the routing-instances statement) in the configuration for Router B. Because they exchange VPN-IPv4 routes, Router C and Router D are configured as PE routers.

In the BGP group to-ibgp, include the family inet labeled-unicast statement to pass labeled IPv4 routes, and configure an EBGP multihop session to pass VPN-IPv4 routes:

Configuration for Router C

Configure two BGP sessions (configure family inet-vpn on both sessions):

  • IBGP session to Router B (group to-ibgp in this example)

  • EBGP session to Router D (group to-ebgp-pe in this example)

Interface t3-0/2/0 is added at the [edit protocols mpls] hierarchy level, allowing BGP to announce routes with labels over the EBGP session.

Configure Router C:

Configuration for Router D

Configure Router D:

Configuration for Router E

The configuration for Router E is very similar to the configuration for Router B:

Configuration for Router F

The configuration for Router F in this example is identical to the configuration for Router F in Interprovider VPN Example—MP-EBGP Between ISP Peer Routers. See Interprovider VPN Example—MP-EBGP Between ISP Peer Routers.

Example: Configuring Interprovider Layer 3 VPN Option A

Interprovider Layer 3 VPN Option A provides interprovider VRF-to-VRF connections at the AS boundary routers (ASBRs). Compared to Option B and Option C, Option A is the least scalable solution.

This example provides a step-by-step procedure to configure interprovider Layer 3 VPN option A, which is one of the recommended implementations of MPLS VPN when that service is required by a customer that has more than one AS and but not all of the customer’s ASs can be serviced by the same service provider. It is organized in the following sections:

Requirements

This example uses the following hardware and software components:

  • Junos OS Release 9.5 or later.

  • Eight M Series, T Series, TX Series, or MX Series Juniper Networks routers.

Overview and Topology

This is the simplest and least scalable interprovider VPN solution to the problem of providing VPN services to a customer that has different sites, not all of which can use the same service provider (SP).

RFC 4364, section 10, refers to this method as Interprovider VRF-to-VRF connections at the AS border routers.

In this configuration:

  • The virtual routing and forwarding (VRF) table in the ASBR of one AS is linked to the VRF table in the ASBR in the other AS. Each ASBR must contain a VRF instance for every VPN configured in both service provider networks. Then an IGP or BGP must be configured between the ASBRs. This has the disadvantage of limiting scalability.

  • In this configuration, the autonomous system boundary routers (ASBRs) at both SPs are configured as regular PE routers, and provide MPLS L3 VPN service to the neighbor SP.

  • Each PE router treats the other as if it were a customer edge (CE) router. ASBRs play the role of regular CE routers for the ASBR of the remote SP. ASBRs see each other as CE devices.

  • A provider edge (PE) router in one autonomous system (AS) attaches directly to a PE router in another AS.

  • The two PE routers are attached by multiple sub-interfaces, at least one for each of the VPNs whose routes need to be passed from AS to AS.

  • The PE routers associate each sub-interface with a VPN routing and forwarding (VRF) table, and use EBGP to distribute unlabeled IPv4 addresses to each other.

  • In this solution, all common VPNs defined at both PEs must also be defined at one or more ASBRs between the two SPs. This is not a very scalable methodology, especially when a transit SP is used by two regional SPs for interconnection.

  • This is a procedure that is simple to configure and it does not require MPLS at the border between ASs. Additionally, it does not scale as well as other recommended procedures.

The topology of the network is shown in Figure 4.

Figure 4: Physical Topology of Interprovider Layer 3 VPN Option A
Physical Topology of Interprovider Layer 3 VPN Option A

Configuration

Note

The procedure presented here is written with the assumption that the reader is already familiar with MPLS MVPN configuration. This example focuses on explaining the unique configuration required for carrier-of-carriers solutions for VPN services to different sites.

To configure interprovider layer 3 VPN option A, perform the following tasks:

Configuring Router CE1

Step-by-Step Procedure

  1. On Router CE1, configure the IP address and protocol family on the Fast Ethernet interface for the link between Router CE1 and Router PE1. Specify the inet address family type.
  2. On Router CE1, configure the IP address and protocol family on the loopback interface. Specify the inet address family type.
  3. On Router CE1, configure a routing protocol. The routing protocol can be a static route, RIP, OSPF, ISIS, or EBGP. In this example we configure OSPF. Include the Fast Ethernet interface for the link between Router CE1 and Router PE1 and the logical loopback interface of Router CE1.

Configuring Router PE1

Step-by-Step Procedure

  1. On Router PE1, configure IPv4 addresses on the SONET, Fast Ethernet, and logical loopback interfaces. Specify the inet address family on all of the interfaces. Specify the mpls address family on the SONET and Fast Ethernet interfaces.
  2. On Router PE1, configure the routing instance for VPN2. Specify the vrf instance type and specify the customer-facing Fast Ethernet interface. Configure a route distinguisher to create a unique VPN-IPv4 address prefix. Apply the VRF import and export policies to enable the sending and receiving of route targets. Configure the OSPF protocol within the VRF. Specify the customer-facing Fast Ethernet interface and specify the export policy to export BGP routes into OSPF.
  3. On Router PE1, configure the RSVP and MPLS protocols to support the label-switched path (LSP). Configure the LSP to Router ASBR1 and specify the IP address of the logical loopback interface on Router ASBR1. Configure a BGP group. Specify the group type as internal. Specify the local address as the logical loopback interface on Router PE1. Specify the neighbor address as the logical loopback interface on Router ASBR1. Specify the inet-vpn address family and unicast traffic type to enable BGP to carry IPv4 network layer reachability information (NLRI) for VPN routes. Configure the OSPF protocol. Specify the core-facing SONET interface and specify the logical loopback interface on Router PE1.
  4. On Router PE1, configure the BGP local autonomous system number.
  5. On Router PE1, configure a policy to export the BGP routes into OSPF.
  6. On Router PE1, configure a policy to add the VRF route target to the routes being advertised for this VPN.
  7. On Router PE1, configure a policy to import routes from BGP that have the test_comm community attached.
  8. On Router PE1, define the test_comm BGP community with a route target.

Configuring Router P1

Step-by-Step Procedure

  1. On Router P1, configure IP addresses for the SONET and Gigabit Ethernet interfaces. Enable the interfaces to process the inet and mpls address families. Configure the IP address for the lo0.0 loopback interface and enable the interface to process the inet address family.
  2. On Router P1, configure the RSVP and MPLS protocols to support the LSP. Specify the SONET and Gigabit Ethernet interfaces.

    Configure the OSPF protocol. Specify the SONET and Gigabit Ethernet interfaces and specify the logical loopback interface. Enable OSPF to support traffic engineering extensions.

Configuring Router ASBR1

Step-by-Step Procedure

  1. On Router ASBR1, configure IP addresses for the Gigabit Ethernet interfaces. Enable the interfaces to process the inet and mpls addresses families. Configure the IP addresses for the lo0.0 loopback interface and enable the interface to process the inet address family.
  2. On Router ASBR1, configure the To_ASBR2 routing instance. Specify the vrf instance type and specify the core-facing Gigabit Ethernet interface. Configure a route distinguisher to create a unique VPN-IPv4 address prefix. Configure a route target for the VPN. Configure the BGP peer group within the VRF. Specify AS 200 as the peer AS and specify the IP address of the Gigabit Ethernet interface on Router ASBR2 as the neighbor address.
  3. On Router ASBR1, configure the RSVP and MPLS protocols to support the LSP by specifying the Gigabit Ethernet interface that is facing the P1 router.

    Configure the OSPF protocol by specifying the Gigabit Ethernet interface that is facing the P1 router and the logical loopback interface. Enable OSPF to support traffic engineering extensions.

  4. On Router ASBR1, create the To-PE1 internal BGP peer group. Specify the local IP peer address as the local lo0.0 address. Specify the neighbor IP peer address as the lo0.0 interface address of Router PE1.
  5. On Router ASBR1, configure the BGP local autonomous system number.

Configuring Router ASBR2

Step-by-Step Procedure

  1. On Router ASBR2, configure IP addresses for the Gigabit Ethernet interfaces. Enable the interfaces to process the inet and mpls address families. Configure the IP address for the lo0.0 loopback interface and enable the interface to process the inet address family.
  2. On Router ASBR2, configure the To_ASBR1 routing instance. Specify the vrf instance type and specify the core-facing Gigabit Ethernet interface. Configure a route distinguisher to create a unique VPN-IPv4 address prefix. Configure a route target for the VPN. Configure the BGP peer group within the VRF. Specify AS 100 as the peer AS and specify the IP address of the Gigabit Ethernet interface on Router ASBR1 as the neighbor address.
  3. On Router ASBR2, configure the RSVP and MPLS protocols to support the LSP by specifying the Gigabit Ethernet interface that is facing the P2 router.

    Configure the OSPF protocol by specifying the Gigabit Ethernet interface that is facing the P2 router and the logical loopback interface. Enable OSPF to support traffic engineering extensions.

  4. On Router ASBR2, create the To-PE2 internal BGP peer group. Specify the local IP peer address as the local lo0.0 address. Specify the neighbor IP peer address as the lo0.0 interface address of Router PE2.
  5. On Router ASBR2, configure the BGP local autonomous system number.

Configuring Router P2

Step-by-Step Procedure

  1. On Router P2, configure IP addresses for the SONET and Gigabit Ethernet interfaces. Enable the interfaces to process the inet and mpls address families. Configure the IP address for the lo0.0 loopback interface and enable the interface to process the inet address family.
  2. On Router P2, configure the RSVP and MPLS protocols to support the LSP. Specify the SONET and Gigabit Ethernet interfaces.

    Configure the OSPF protocol. Specify the SONET and Gigabit Ethernet interfaces and specify the logical loopback interface. Enable OSPF to support traffic engineering extensions.

Configuring Router PE2

Step-by-Step Procedure

  1. On Router PE2, configure IPv4 addresses on the SONET, Fast Ethernet, and logical loopback interfaces. Specify the inet address family on all of the interfaces. Specify the mpls address family on the SONET and Fast Ethernet interfaces.
  2. On Router PE2, configure the routing instance for VPN2. Specify the vrf instance type and specify the customer-facing Fast Ethernet interface. Configure a route distinguisher to create a unique VPN-IPv4 address prefix. Apply the VRF import and export policies to enable the sending and receiving of route targets. Configure the BGP peer group within the VRF. Specify AS 20 as the peer AS and specify the IP address of the Fast Ethernet interface on Router CE2 as the neighbor address.
  3. On Router PE2, configure the RSVP and MPLS protocols to support the LSP. Configure the LSP to ASBR2 and specify the IP address of the logical loopback interface on Router ASBR2. Configure a BGP group. Specify the group type as internal. Specify the local address as the logical loopback interface on Router PE2. Specify the neighbor address as the logical loopback interface on the Router ASBR2. Specify the inet-vpn address family and unicast traffic type to enable BGP to carry IPv4 NLRI for VPN routes. Configure the OSPF protocol. Specify the core-facing SONET interface and specify the logical loopback interface on Router PE2.
  4. On Router PE2, configure the BGP local autonomous system number.
  5. On Router PE2, configure a policy to add the VRF route target to the routes being advertised for this VPN.
  6. On Router PE2, configure a policy to import routes from BGP that have the test_comm community attached.
  7. On Router PE2, define the test_comm BGP community with a route target.

Configuring Router CE2

Step-by-Step Procedure

  1. On Router CE2, configure the IP address and protocol family on the Fast Ethernet interface for the link between Router CE2 and Router PE2. Specify the inet address family type.
  2. On Router CE2, configure the IP address and protocol family on the loopback interface. Specify the inet address family type.
  3. On Router CE2, define a policy named myroutes that accepts direct routes.
  4. On Router CE2, configure a routing protocol. The routing protocol can be a static route, RIP, OSPF, ISIS, or EBGP. In this example, we configure EBGP. Specify AS 200 as the peer AS and specify the BGP neighbor IP address as the Fast Ethernet interface of Router PE2.
  5. On Router CE2, configure the BGP local autonomous system number.

Verifying the VPN Operation

Step-by-Step Procedure

  1. Commit the configuration on each router.Note

    The MPLS labels shown in this example will be different than the labels used in your configuration.

  2. On Router PE1, display the routes for the vpn2CE1 routing instance using the show ospf route command. Verify that the 192.0.2.1 route is learned from OSPF.
    user@PE1> show ospf route instance vpn2CE1
  3. On Router PE1, use the show route advertising-protocol command to verify that Router PE1 advertises the 192.0.2.1 route to Router ASBR1 using MP-BGP with the VPN MPLS label.
    user@PE1> show route advertising-protocol bgp 192.0.2.4 extensive
  4. On Router ASBR1, use the show route receive-protocol command to verify that the router receives and accepts the 192.0.2.1 route and places it in the To_ASBR2.inet.0 routing table.
    user@ASBR1> show route receive-protocol bgp 192.0.2.2 extensive
  5. On Router ASBR1, use the show route advertising-protocol command to verify that Router ASBR1 advertises the 192.0.2.1 route to Router ASBR2.
    user@ASBR1> show route advertising-protocol bgp 192.168.3.8 extensive
  6. On Router ASBR2, use the show route receive-protocol command to verify that the router receives and accepts the 192.0.2.1 route and places it in the To_ASBR1.inet.0 routing table.
    user@ASBR2> show route receive-protocol bgp 192.168.3.7 extensive
  7. On Router ASBR2, use the show route advertising-protocol command to verify that Router ASBR2 advertises the 192.0.2.1 route to Router PE2.
    user@ASBR2> show route advertising-protocol bgp 192.0.2.7 extensive
  8. On Router PE2, use the show route receive-protocol command to verify that the router receives and accepts the 192.0.2.1 route and places it in the vpn2CE2.inet.0 routing table.
    user@PE2> show route receive-protocol bgp 192.0.2.5 extensive
  9. On Router PE2, use the show route advertising-protocol command to verify that Router PE2 advertises the 192.0.2.1 route to Router CE2 through the To_CE2 peer group.
    user@PE2> show route advertising-protocol bgp 192.168.6.14 extensive
  10. On Router CE2, use the show route command to verify that Router CE2 receives the 192.0.2.1 route from Router PE2.
    user@CE2> show route 192.0.2.1
  11. On Router CE2, use the ping command and specify 192.0.2.8 as the source of the ping packets to verify connectivity with Router CE1.
    user@CE2> ping 192.0.2.1 source 192.0.2.8
  12. On Router PE2, use the show route command to verify that the traffic is sent with an inner label of 299936 and a top label of 299776.
    user@PE2> show route 192.0.2.1 detail
  13. On Router ASBR2, use the show route table command to verify that Router ASBR2 receives the traffic.
    user@ASBR2# show route table mpls.0 detail
  14. On Router ASBR2, use the show route table command to verify that Router ASBR2 receives the traffic.
    user@ASBR2# show route 192.0.2.1 detail
  15. On Router ASBR1, use the show route command to verify that ASBR1 sends traffic toward PE1 with the top label 299792 and VPN label 299856.
    user@ASBR1# show route 192.0.2.1 detail
  16. On Router PE1, use the show route table command to verify that Router PE1 receives the traffic with label 299856, pops the label,l and the traffic is sent toward Router CE1 through interface fe-1/2/3.0.
    lab@PE1# show route table mpls.0 detail
  17. On Router PE1, use the show route command to verify that PE1 receives the traffic after the top label is popped by Router P and the traffic is sent toward Router CE1 through interface fe-1/2/3.0.
    lab@PE1# show route 192.0.2.1 detail

Example: Configuring Interprovider Layer 3 VPN Option B

Interprovider Layer 3 VPN Option B provides interprovider EBGP redistribution of labeled VPN-IPv4 routes from AS to neighboring AS. This solution is considered to be more scalable than Option A, but not as scalable as Option C.

This example provides a step-by-step procedure to configure interprovider layer 3 VPN option B, which is one of the recommended implementations of an MPLS VPN when that service is required by a customer that has more than one AS, but not all of the customer’s ASs can be serviced by the same service provider. It is organized in the following sections:

Requirements

This example uses the following hardware and software components:

  • Junos OS Release 9.5 or later.

  • Eight M Series, T Series, TX Series, QFX10000, or MX Series Juniper Networks routers.

Configuration Overview and Topology

Interprovider layer 3 VPN option B is a somewhat scalable solution to the problem of providing VPN services to a customer that has different sites, not all of which can use the same service provider. RFC 4364, section 10, refers to this method as interprovider EBGP redistribution of labeled VPN-IPv4 routes from AS to neighboring AS.

In the topology shown in Figure 1, the following events occur:

  • The PE routers use IBGP to redistribute labeled VPN-IPv4 routes either to an ASBR, or to a route reflector of which an ASBR is a client.

  • The ASBR then uses EBGP to redistribute those labeled VPN-IPv4 routes to an ASBR in another AS, which distributes them to the PE routers in that AS, or to another ASBR for distribution.

  • Labeled VPN-IPv4 routes are distributed between ASBR routers on each site. There is no need to define a separate VPN routing and forwarding instance (VRF) for each common VPN that resides on two different SPs.

  • Router PE2 distributes VPN-IPv4 routes to Router ASBR2 using MP-IBGP.

  • Router ASBR2 distributes these labeled VPN-IPv4 routes to Router ASBR1, using the MP-EBGP session between them.

  • Router ASBR1 redistributes those routes to Router PE1, using MP-IBGP. Each time a label is advertised, routers change the next-hop information and labels.

  • An MPLS path is established between Router PE1 and Router PE2. This path enables changing of the next-hop attribute for the routes that are learned from the neighbor SP router and map the incoming label for the given routes to the outgoing label advertised to PE routers in the internal network.

  • The ingress PE router inserts two labels onto the IP packet coming from the end customer. The inner label is for the VPN-IPv4 routes learned from internal ASBRs and the outer label is for the route to the internal ASBR, obtained through resource reservation protocol (RSVP) or label distribution protocol (LDP).

  • When a packet arrives at the ASBR, it removes the outer label (when explicit-null signaling is used; otherwise, penultimate hop-popping (PHP) pops the label) and swaps the inner label with the label obtained from the neighbor ASBR through MP-EBGP label and prefix advertisements.

  • The second ASBR swaps the VPN-IPv4 label and pushes another label to reach the PE router in its own AS.

  • The remaining process is the same as for a regular VPN.

Note

In this solution, ASBR routers keep all VPN-IPv4 routes in the routing information base (RIB), and the labels associated with the prefixes are kept in the forwarding information base (FIB). Because the RIB and FIB tables can take occupy much of the respective allocated memory, this solution is not very scalable for an interprovider VPN.

If a transit SP is used between SP1 and SP2, the transit SP also has to keep all VPN-IPv4 routes in the RIB and the corresponding labels in the FIB. The ASBRs at the transit SP have the same functionality as ASBRs in the SP1 or SP2 networks in this solution.

The topology of the network is shown in Figure 5.

Figure 5: Physical Topology of Interprovider Layer 3 VPN Option B
Physical Topology of Interprovider Layer 3 VPN Option B

Configuration

Note

The procedure presented here is written with the assumption that the reader is already familiar with MPLS MVPN configuration. This example focuses on explaining the unique configuration required for carrier-of-carriers solutions for VPN services to different sites.

To configure layer 3 VPN option B, perform the following tasks:

Configuring Router CE1

Step-by-Step Procedure

  1. On Router CE1, configure the IP address and protocol family on the Fast Ethernet interface for the link between Router CE1 and Router PE1. Specify the inet address family type.
  2. On Router CE1, configure the IP address and protocol family on the loopback interface. Specify the inet address family type.
  3. On Router CE1, configure a routing protocol. Include the logical interface for the link between Router CE1 and Router PE1 and the logical loopback interface of Router CE1. The routing protocol can be a static route, RIP, OSPF, ISIS, or EBGP. In this example we configure OSPF.

Configuring Router PE1

Step-by-Step Procedure

  1. On Router PE1, configure IPv4 addresses on the SONET, Fast Ethernet, and logical loopback interfaces. Specify the inet address family on all of the interfaces. Specify the mpls address family on the SONET and Fast Ethernet interfaces.
  2. On Router PE1, configure the routing instance for VPN2. Specify the vrf instance type and specify the customer-facing Fast Ethernet interface. Configure a route distinguisher to create a unique VPN-IPv4 address prefix. Apply the VRF import and export policies to enable the sending and receiving of route targets. Configure the OSPF protocol within the VRF. Specify the customer-facing Fast Ethernet interface and specify the export policy to export BGP routes into OSPF.
  3. On Router PE1, configure the RSVP and MPLS protocols to support the label-switched path (LSP). Configure the LSP to Router ASBR1 and specify the IP address of the logical loopback interface on Router ASBR1. Configure a BGP group. Specify the group type as internal. Specify the local address as the logical loopback interface on Router PE1. Specify the neighbor address as the logical loopback interface on Router ASBR1. Specify the inet-vpn address family and unicast traffic type to enable BGP to carry IPv4 network layer reachability information (NLRI) for VPN routes. Configure the OSPF protocol. Specify the core-facing SONET interface and specify the logical loopback interface on Router PE1.
  4. On Router PE1, configure the BGP local autonomous system number.
  5. On Router PE1, configure a policy to export the BGP routes into OSPF.
  6. On Router PE1, configure a policy to add the VRF route target to the routes being advertised for this VPN.
  7. On Router PE1, configure a policy to import routes from BGP that have the test_comm community attached.
  8. On Router PE1, define the test_comm BGP community with a route target.

Configuring Router P1

Step-by-Step Procedure

  1. On Router P1, configure IP addresses for the SONET and Gigabit Ethernet interfaces. Enable the interfaces to process the inet and mpls address families. Configure the IP addresses for the lo0.0 loopback interface and enable the interface to process the inet address family.
  2. On Router P1, configure the RSVP and MPLS protocols to support the LSP. Specify the SONET and Gigabit Ethernet interfaces.

    Configure the OSPF protocol. Specify the SONET and Gigabit Ethernet interfaces and specify the logical loopback interface. Enable OSPF to support traffic engineering extensions.

Configuring Router ASBR1

Step-by-Step Procedure

  1. On Router ASBR1, configure IP addresses for the Gigabit Ethernet interfaces. Enable the interfaces to process the inet and mpls addresses families. Configure the IP addresses for the lo0.0 loopback interface and enable the interface to process the inet address family.
  2. On Router ASBR1, configure the RSVP and MPLS protocols to support the LSP by specifying the Gigabit Ethernet interface facing the P1 router and the lo0.0 logical loopback interface.

    Configure the OSPF protocol by specifying the Gigabit Ethernet interface that is facing the P1 router and the logical loopback interface. Enable OSPF to support traffic engineering extensions.

  3. On Router ASBR1, create the To-PE1 internal BGP peer group. Specify the local IP peer address as the local lo0.0 address. Specify the neighbor IP peer address as the lo0.0 interface address of Router PE1.
  4. On Router ASBR1, create the To_ASBR2 external BGP peer group. Enable the router to use BGP to advertise NLRI for unicast routes. Specify the neighbor IP peer address as the Gigabit Ethernet interface address of Router ASBR2.
  5. On Router ASBR1, configure the BGP local autonomous system number.

Configuring Router ASBR2

Step-by-Step Procedure

  1. On Router ASBR2, configure IP addresses for the Gigabit Ethernet interfaces. Enable the interfaces to process the inet and mpls address families. Configure the IP address for the lo0.0 loopback interface and enable the interface to process the inet address family.
  2. On Router ASBR2, configure the RSVP and MPLS protocols to support the LSP by specifying the Gigabit Ethernet interface that is facing the P2 router.

    Configure the OSPF protocol by specifying the Gigabit Ethernet interface that is facing the P2 router and the logical loopback interface. Enable OSPF to support traffic engineering extensions.

  3. On Router ASBR2, create the To-PE2 internal BGP peer group. Specify the local IP peer address as the local lo0.0 address. Specify the neighbor IP peer address as the lo0.0 interface address of Router PE2.
  4. On Router ASBR2, create the To-ASBR1 external BGP peer group. Enable the router to use BGP to advertise NLRI for unicast routes. Specify the neighbor IP peer address as the Gigabit Ethernet interface on Router ASBR1.
  5. On Router ASBR2, configure the BGP local autonomous system number.

Configuring Router P2

Step-by-Step Procedure

  1. On Router P2, configure IP addresses for the SONET and Gigabit Ethernet interfaces. Enable the interfaces to process the inet and mpls address families. Configure the IP address for the lo0.0 loopback interface and enable the interface to process the inet address family.
  2. On Router P2, configure the RSVP and MPLS protocols to support the LSP. Specify the SONET and Gigabit Ethernet interfaces.

    Configure the OSPF protocol. Specify the SONET and Gigabit Ethernet interfaces and specify the logical loopback interface. Enable OSPF to support traffic engineering extensions.

Configuring Router PE2

Step-by-Step Procedure

  1. On Router PE2, configure IPv4 addresses on the SONET, Fast Ethernet, and logical loopback interfaces. Specify the inet address family on all of the interfaces. Specify the mpls address family on the SONET and Fast Ethernet interfaces.
  2. On Router PE2, configure the routing instance for VPN2. Specify the vrf instance type and specify the customer-facing Fast Ethernet interface. Configure a route distinguisher to create a unique VPN-IPv4 address prefix. Apply the VRF import and export policies to enable the sending and receiving of route targets. Configure the BGP peer group within the VRF. Specify AS 20 as the peer AS and specify the IP address of the Fast Ethernet interface on Router CE1 as the neighbor address.
  3. On Router PE2, configure the RSVP and MPLS protocols to support the LSP. Configure the LSP to ASBR2 and specify the IP address of the logical loopback interface on Router ASBR2. Configure a BGP group. Specify the group type as internal. Specify the local address as the logical loopback interface on Router PE2. Specify the neighbor address as the logical loopback interface on the Router ASBR2. Specify the inet-vpn address family and unicast traffic type to enable BGP to carry IPv4 NLRI for VPN routes. Configure the OSPF protocol. Specify the core-facing SONET interface and the logical loopback interface on Router PE2.
  4. On Router PE2, configure the BGP local autonomous system number.
  5. On Router PE2, configure a policy to add the VRF route target to the routes being advertised for this VPN.
  6. On Router PE2, configure a policy to import routes from BGP that have the test_comm community attached.
  7. On Router PE1, define the test_comm BGP community with a route target.

Configuring Router CE2

Step-by-Step Procedure

  1. On Router CE2, configure the IP address and protocol family on the Fast Ethernet interface for the link between Router CE2 and Router PE2. Specify the inet address family type.
  2. On Router CE2, configure the IP address and protocol family on the loopback interface. Specify the inet address family type.
  3. On Router CE2, define a policy named myroutes that accepts direct routes.
  4. On Router CE2, configure a routing protocol. The routing protocol can be a static route, RIP, OSPF, ISIS, or EBGP. In this example, we configure EBGP. Specify AS 200 as the peer AS and specify the BGP neighbor IP address as the Fast Ethernet interface of Router PE2. Include the export statement.
  5. On Router CE2, configure the BGP local autonomous system number.

Verifying the VPN Operation

Step-by-Step Procedure

  1. Commit the configuration on each router.Note

    The MPLS labels shown in this example will be different than the labels used in your configuration.

  2. On Router PE1, display the routes for the vpn2CE1 routing instance using the show ospf route command. Verify that the 192.0.2.1 route is learned from OSPF.
    user@PE1> show ospf route instance vpn2CE1
  3. On Router PE1, use the show route advertising-protocol command to verify that Router PE1 advertises the 192.0.2.1 route to Router ASBR1 using MP-BGP with the VPN MPLS label.
    user@PE1> show route advertising-protocol bgp 192.0.2.4 extensive
  4. On Router ASBR1, use the show route receive-protocol command to verify that the router receives and accepts the 192.0.2.1 route and places it in the bgp.l3vpn.0 routing table.
    user@ASBR1> show route receive-protocol bgp 192.0.2.2 extensive
  5. On Router ASBR1, use the show route advertising-protocol command to verify that Router ASBR1 advertises the 192.0.2.1 route to Router ASBR2.
    user@ASBR1> show route advertising-protocol bgp 192.168.3.6 extensive
  6. On Router ASBR2, use the show route receive-protocol command to verify that the router receives and accepts the 192.0.2.1 route and places it in the bgp.l3vpn.0 routing table.
    user@ASBR2> show route receive-protocol bgp 192.168.3.8 extensive
  7. On Router ASBR2, use the show route advertising-protocol command to verify that Router ASBR2 advertises the 192.0.2.1 route to Router PE2.
    user@ASBR2> show route advertising-protocol bgp 192.0.2.7 extensive
  8. On Router PE2, use the show route receive-protocol command to verify that the router receives and accepts the 192.0.2.1 route and places it in the vpn2CE2.inet.0 routing table.
    user@PE2> show route receive-protocol bgp 192.0.2.5 extensive
  9. On Router PE2, use the show route advertising-protocol command to verify that Router PE2 advertises the 192.0.2.1 route to Router CE2 through the To_CE2 peer group.
    user@PE2> show route advertising-protocol bgp 192.168.6.14 extensive
  10. On Router CE2, use the show route command to verify that Router CE2 receives the 192.0.2.1 route from Router PE2.
    user@CE2> show route 192.0.2.1
  11. On Router CE2, use the ping command and specify 192.0.2.8 as the source of the ping packets to verify connectivity with Router CE1.
    user@CE2> ping 192.0.2.1 source 192.0.2.8
  12. On Router PE2, use the show route command to verify that the traffic is sent with an inner label of 300048 and a top label of 299776.
    user@PE2> show route 192.0.2.1 detail
  13. On Router ASBR2, use the show route table command to verify that Router ASBR2 receives the traffic after the top label is popped by Router P2, that label 300048 is swapped with label 299984, and that the packet is sent toward Router ASBR1 through interface ge-0/1/1.0.
    user@ASBR2> show route table mpls.0 detail
  14. On Router ASBR1, use the show route table command to verify that Router ASBR1 receives the traffic with label 299984, swaps the label with 299952, and pushes a new top label of 299792.
    user@ASBR1> show route table mpls.0 detail
  15. On Router PE1, use the show route table command to verify that Router PE1 receives the traffic with label 299952, and then pops the inner label.
    user@PE1> show route route table mpls.0 detail

Example: Configuring Interprovider Layer 3 VPN Option C

Interprovider Layer 3 VPN Option C provides interprovider multihop EBGP redistribution of labeled VPN-IPv4 routes between source and destination ASs, with EBGP redistribution of labeled IPv4 routes from AS to neighboring AS. Compared to Option A and Option B, Option C is the most scalable solution. To configure an interprovider Layer 3 VPN option C service, you need to configure the AS border routers and the PE routers connected to the end customer’s CE routers using multihop EBGP.

This example provides a step-by-step procedure to configure interprovider layer 3 VPN option C, which is one of the recommended implementations of MPLS VPN when that service is required by a customer that has more than one AS but not all of the customer’s ASs can be serviced by the same service provider (SP). It is organized in the following sections:

Requirements

This example requires the following hardware and software components:

  • Junos OS Release 9.5 or later.

  • Eight Juniper Networks M Series Multiservice Edge Routers, T Series Core Routers, TX Matrix Routers, or MX Series 5G Universal Routing Platforms.

Configuration Overview and Topology

Interprovider layer 3 VPN option C is a very scalable interprovider VPN solution to the problem of providing VPN services to a customer that has different sites, not all of which can use the same SP.

RFC 4364 section 10, refers to this method as multihop EBGP redistribution of labeled VPN-IPv4 routes between source and destination ASs, with EBGP redistribution of labeled IPv4 routes from AS to neighboring AS.

This solution is similar to the solution described in Implementing Interprovider Layer 3 VPN Option B, except internal IPv4 unicast routes are advertised instead of external VPN-IPv4-unicast routes, using EBGP. Internal routes are internal to leaf SPs (SP1 and SP2 in this example), and external routes are those learned from the end customer requesting VPN services.

In this configuration:

  • After the loopback address of Router PE2 is learned by Router PE1 and the loopback address of Router PE1 is learned by Router PE2, the end PE routers establish an MP-EBGP session for exchanging VPN-IPv4 routes.

  • Since VPN-IPv4 routes are exchanged among end PE routers, any other router on the path from Router PE1 and Router PE2 does not need to keep or install VPN-IPv4 routes in their routing information base (RIB) or forwarding information base (FIB) tables.

  • An MPLS path needs to be established between Router PE1 and Router PE2.

RFC 4364 describes only one solution that uses a BGP labeled-unicast approach. In this approach, the ASBR routers advertise the loopback addresses of the PE routers and associate each prefix with a label according to RFC 3107. Service providers may use RSVP or LDP to establish an LSP between ASBR routers and PE routers in their internal network.

In this network, ASBR2 receives label information associated with the loopback IP address of Router PE1 and advertises another label to Router ASBR1 using MP-EBGP labeled-unicast. Meanwhile, the ASBRs build their own MPLS forwarding table according to the received and advertised routes and labels. Router ASBR1 uses its own IP address as the next-hop information.

Router ASBR2 receives this prefix associated with a label, assigns another label, changes the next-hop address to its own address, and advertises it to Router PE1. Router PE1 now has an update with the label information and next-hop to Router ASBR1. Also, Router PE1 already has a label associated with the IP address of Router ASBR1. If Router PE1 sends an IP packet to Router PE2, it pushes two labels: one for the IP address of Router PE2 (obtained using MP-IBGP labeled-unicast advertisement) and one for the IP address of Router ASBR1 (obtained using LDP or RSVP).

Router ASBR1 then pops the outer label and swaps the inner label with the label learned from a neighbor ASBR for its neighboring PE router. Router ASBR2 performs a similar function and swaps the incoming label (only one) and pushes another label that is associated with the address of Router PE2. Router PE2 pops both labels and passes the remaining IP packet to its own CPU. After the end-to-end connection among the PE routers is created, the PE routers establish an MP-EBGP session to exchange VPN-IPv4 routes.

In this solution, PE routers push three labels onto the IP packet coming from the VPN end user. The inner-most label, obtained using MP-EBGP, determines the correct VPN routing and forwarding (VRF) routing instance at the remote PE. The middle label is associated with the IP address of the remote PE and is obtained from an ASBR using MP-IBGP labeled-unicast. The outer label is associated with the IP addresses of the ASBRs and is obtained using LDP or RSVP.

The physical topology of the network is shown in Figure 6.

Figure 6: Physical Topology of Interprovider Layer 3 VPN Option C
Physical Topology of
Interprovider Layer 3 VPN Option C

Configuration

Note

The procedure presented here is written with the assumption that the reader is already familiar with MPLS MVPN configuration. This example focuses on explaining the unique configuration required for carrier-of-carriers solutions for VPN services to different sites.

To configure interprovider layer 3 VPN option C, perform the following tasks:

Configuring Router CE1

Step-by-Step Procedure

  1. On Router CE1, configure the IP address and protocol family on the Fast Ethernet interface for the link between Router CE1 and Router PE1. Specify the inet address family type.
  2. On Router CE1, configure the IP address and protocol family on the loopback interface. Specify the inet address family type.
  3. On Router CE1, configure a routing protocol. The routing protocol can be a static route, RIP, OSPF, ISIS, or EBGP. In this example we configure OSPF. Include the logical interface for the link between Router CE1 and Router PE1 and the logical loopback interface of Router CE1.

Configuring Router PE1

Step-by-Step Procedure

  1. On Router PE1, configure IPv4 addresses on the SONET, Fast Ethernet, and logical loopback interfaces. Specify the inet address family on all of the interfaces. Specify the mpls address family on the SONET interfaces.
  2. On Router PE1, configure the routing instance for VPN2. Specify the vrf instance type and specify the customer-facing Fast Ethernet interface. Configure a route distinguisher to create a unique VPN-IPv4 address prefix. Apply the VRF import and export policies to enable the sending and receiving of route targets. Configure the OSPF protocol within the VRF. Specify the customer-facing Fast Ethernet interface and specify the export policy to export BGP routes into OSPF.
  3. On Router PE1, configure the RSVP and MPLS protocols to support the LSP. Configure the LSP to Router ASBR1 and specify the IP address of the logical loopback interface on Router ASBR1. Configure the OSPF protocol. Specify the core-facing SONET interface and specify the logical loopback interface on Router PE1.
  4. On Router PE1, configure the To_ASBR1 peer BGP group. Specify the group type as internal. Specify the local address as the logical loopback interface on Router PE1. Specify the neighbor address as the logical loopback interface on Router ASBR1. Specify the inet address family. For a PE router to install a route in the VRF, the next hop must resolve to a route stored within the inet.3 table. The labeled-unicast resolve-vpn statements allow labeled routes to be placed in the inet.3 routing table for route resolution, which are then resolved for PE router connections where the remote PE is located across another AS.
  5. On Router PE1, configure multihop EBGP toward PE2. Specify the inet-vpn family.
  6. On Router PE1, configure the BGP local autonomous system number.
  7. On Router PE1, configure a policy to export the BGP routes into OSPF.
  8. On Router PE1, configure a policy to add the VRF route target to the routes being advertised for this VPN.
  9. On Router PE1, configure a policy to import routes from BGP that have the test_comm community attached.
  10. On Router PE1, define the test_comm BGP community with a route target.

Configuring Router P1

Step-by-Step Procedure

  1. On Router P1, configure IP addresses for the SONET and Gigabit Ethernet interfaces. Enable the interfaces to process the inet and mpls address families. Configure the IP address for the lo0.0 loopback interface and enable the interface to process the inet address family.
  2. On Router P1, configure the RSVP and MPLS protocols to support the LSP. Specify the SONET and Gigabit Ethernet interfaces.

    Configure the OSPF protocol. Specify the SONET and Gigabit Ethernet interfaces and specify the logical loopback interface. Enable OSPF to support traffic engineering extensions.

Configuring Router ASBR1

Step-by-Step Procedure

  1. On Router ASBR1, configure IP addresses for the Gigabit Ethernet interfaces. Enable the interfaces to process the inet and mpls addresses families. Configure the IP addresses for the lo0.0 loopback interface and enable the interface to process the inet address family.
  2. On Router ASBR1, configure the protocols to support the LSP.

    Configure the RSVP protocol by specifying the Gigabit Ethernet interface that is facing the P1 router and the logical loopback interface.

    Configure the MPLS protocol by specifying the Gigabit Ethernet interfaces and the logical loopback interface. Include the traffic-engineering bgp-igp-both-ribs statement at the [edit protocols mpls] hierarchy level.

    Configure the OSPF protocol on the Gigabit Ethernet interface facing the P1 router and the logical loopback interface. Enable OSPF to support traffic engineering extensions.

  3. On Router ASBR1, create the To-PE1 internal BGP peer group. Specify the local IP peer address as the local lo0.0 address. Specify the neighbor IP peer address as the Gigabit Ethernet interface address of Router PE1.
  4. On Router ASBR1, create the To-ASBR2 external BGP peer group. Enable the router to use BGP to advertise network layer reachability information (NLRI) for unicast routes. Specify the neighbor IP peer address as the Gigabit Ethernet interface address on Router ASBR2.
  5. On Router ASBR1, configure the BGP local autonomous system number.
  6. On Router ASBR 1, configure a policy to import routes from BGP that match the 192.0.2.2/24 route.
  7. On Router ASBR 1, define a next-hop self policy and apply it to the IBGP sessions.

Configuring Router ASBR2

Step-by-Step Procedure

  1. On Router ASBR2, configure IP addresses for the Gigabit Ethernet interfaces. Enable the interfaces to process the inet and mpls address families. Configure the IP address for the lo0.0 loopback interface and enable the interface to process the inet address family.
  2. On Router ASBR2, configure the protocols to support the LSP.

    Configure the RSVP protocol by specifying the Gigabit Ethernet interface facing the P2 router and the logical loopback interface .

    Configure the MPLS protocol by specifying the Gigabit Ethernet interfaces and the logical loopback interface. Include the traffic-engineering bgp-igp-both-ribs statement at the [edit protocols mpls] hierarchy level.

    Configure the OSPF protocol on the Gigabit Ethernet interface facing the P2 router and the logical loopback interface . Enable OSPF to support traffic engineering extensions.

  3. On Router ASBR2, create the To-PE2 internal BGP peer group. Specify the local IP peer address as the local lo0.0 address. Specify the neighbor IP peer address as the lo0.0 interface address of Router PE2.
  4. On Router ASBR2, create the To-ASBR1 external BGP peer group. Enable the router to use BGP to advertise NLRI for unicast routes. Specify the neighbor IP peer address as the Gigabit Ethernet interface address on Router ASBR1.
  5. On Router ASBR2 configure the BGP local autonomous system number.
  6. On Router ASBR2, configure a policy to import routes from BGP that match the 192.0.2.7/24 route.
  7. On Router ASBR 2, define a next-hop self policy.

Configuring Router P2

Step-by-Step Procedure

  1. On Router P2, configure IP addresses for the SONET and Gigabit Ethernet interfaces. Enable the interfaces to process the inet and mpls addresses families. Configure the IP addresses for the lo0.0 loopback interface and enable the interface to process the inet address family.
  2. On Router P2, configure the RSVP and MPLS protocols to support the LSP. Specify the SONET and Gigabit Ethernet interfaces.

    Configure the OSPF protocol. Specify the SONET and Gigabit Ethernet interfaces and specify the logical loopback interface. Enable OSPF to support traffic engineering extensions.

Configuring Router PE2

Step-by-Step Procedure

  1. On Router PE2, configure IPv4 addresses on the SONET, Fast Ethernet, and logical loopback interfaces. Specify the inet address family on all of the interfaces. Specify the mpls address family on the SONET interface.
  2. On Router PE2, configure the routing instance for VPN2. Specify the vrf instance type and specify the customer-facing Fast Ethernet interface. Configure a route distinguisher to create a unique VPN-IPv4 address prefix. Apply the VRF import and export policies to enable the sending and receiving of route targets. Configure the BGP peer group within the VRF. Specify AS 20 as the peer AS and specify the IP address of the Fast Ethernet interface on Router CE1 as the neighbor address.
  3. On Router PE2, configure the RSVP and MPLS protocols to support the LSP. Configure the LSP to ASBR2 and specify the IP address of the logical loopback interface on Router ASBR2. Configure the OSPF protocol. Specify the core-facing SONET interface and specify the logical loopback interface on Router PE2.
  4. On Router PE2, configure the To_ASBR2 BGP group. Specify the group type as internal. Specify the local address as the logical loopback interface on Router PE2. Specify the neighbor address as the logical loopback interface on the Router ASBR2.
  5. On Router PE2, configure multihop EBGP towards Router PE1 Specify the inet-vpn address family.
  6. On Router PE2, configure the BGP local autonomous system number.
  7. On Router PE2, configure a policy to add the VRF route target to the routes being advertised for this VPN.
  8. On Router PE2, configure a policy to import routes from BGP that have the test_comm community attached.
  9. On Router PE1, define the test_comm BGP community with a route target.

Configuring Router CE2

Step-by-Step Procedure

  1. On Router CE2, configure the IP address and protocol family on the Fast Ethernet interface for the link between Router CE2 and Router PE2. Specify the inet address family type.
  2. On Router CE2, configure the IP address and protocol family on the loopback interface. Specify the inet address family type.
  3. On Router CE2, define a policy named myroutes that accepts direct routes.
  4. On Router CE2, configure a routing protocol. The routing protocol can be a static route, RIP, OSPF, ISIS, or EBGP. In this example, we configure EBGP. Specify the BGP neighbor IP address as the logical loopback interface of Router PE1. Apply the myroutes policy.
  5. On Router CE2, configure the BGP local autonomous system number.

Verifying the VPN Operation

Step-by-Step Procedure

  1. Commit the configuration on each router.Note

    The MPLS labels shown in this example will be different than the labels used in your configuration.

  2. On Router PE1, display the routes for the vpn2CE1 routing instance using the show ospf route command. Verify that the 192.0.2.1 route is learned from OSPF.
    user@PE1> show ospf route instance vpn2CE1
  3. On Router PE1, use the show route advertising-protocol command to verify that Router PE1 advertises the 192.0.2.1 route to Router PE2 using MP-BGP with the VPN MPLS label.
    user@PE1> show route advertising-protocol bgp 192.0.2.7 extensive
  4. On Router ASBR1, use the show route advertising-protocol command to verify that Router ASBR1 advertises the 192.0.2.2 route to Router ASBR2.
    user@ASBR1> show route advertising-protocol bgp 192.168.3,8 extensive
  5. On Router ASBR2, use the show route receive-protocol command to verify that the router receives and accepts the 192.0.2.2 route .
    user@ASBR2> show route receive-protocol bgp 192.168.3.7 extensive
  6. On Router ASBR2, use the show route advertising-protocol command to verify that Router ASBR2 advertises the 192.0.2.2 route to Router PE2.
    user@ASBR2> show route advertising-protocol bgp 192.0.2.7 extensive
  7. On Router PE2, use the show route receive-protocol command to verify that Router PE2 receives the route and puts it in the inet.0. routing table. Verify that Router PE2 also receives the update from Router PE1 and accepts the route.
    user@PE2> show route receive-protocol bgp 192.0.2.5 extensive
  8. On Router PE2, use the show route receive-protocol command to verify that Router PE2 puts the route in the routing table of the vpn2CE2 routing instance and advertises the route to Router CE2 using EBGP.
    user@PE2> show route receive-protocol bgp 192.0.2.2 detail
  9. On Router PE2, use the show route advertising-protocol command to verify that Router PE2 advertises the 192.0.2.1 route to Router CE2 through the vpn2CE2 peer group.
    user@PE2> show route advertising-protocol bgp 192.168.6.14 extensive
  10. On Router CE2, use the show route command to verify that Router CE2 receives the 192.0.2.1 route from Router PE2.
    user@CE2> show route 192.0.2.1
  11. On Router CE2, use the ping command and specify 192.0.2.8 as the source of the ping packets to verify connectivity with Router CE1.
    user@CE2> ping 192.0.2.1 source 192.0.2.8
  12. On Router PE2, use the show route command to verify that the traffic is sent with an inner label of 300016, a middle label of 300192, and a top label of 299776.
    user@PE2> show route 192.0.2.1 detail
  13. On Router ASBR2, use the show route table command to verify that Router ASBR2 receives the traffic after the top label is popped by Router P2. Verify that label 300192 is a swapped with label 300176 and the traffic is sent towards Router ASBR1 using interface ge-0/1/1.0. At this point, the bottom label 300016 is preserved.
    user@ASBR2# show route table mpls.0 detail
  14. On Router ASBR1, use the show route table command to verify that when Router ASBR1 receives traffic with label 300176, it swaps the label with 299824 to reach Router PE1.
    user@ASBR1> show route table mpls.0 detail
  15. On Router PE1, use the show route table command to verify that Router PE1 receives the traffic after the top label is popped by Router P1. Verify that label 300016 is popped and the traffic is sent towards Router CE1 using interface fe-1/2/3.0.
    user@PE1> show route table mpls.0 detail