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Example: Configuring MPLS Egress Protection Service Mirroring for BGP Signaled Layer 2 Services

 

Starting in Junos OS Release 14.2, Junos OS supports the restoration of egress traffic when there is a link or node failure in the egress PE node. If there is a link or node failure in the core network, a protection mechanism such as MPLS fast reroute can be triggered on the transport LSPs between the PE routers to repair the connection within tens of milliseconds. An egress protection LSP addresses the problem of a node-link failure at the edge of the network (for example, a failure of a PE router).

This example shows how to configure link protection for BGP signaled Layer 2 services.

Requirements

MX Series Routers running Junos OS Release 14.2 or later.

Overview

If there is a link or node failure in the core network, a protection mechanism such as MPLS fast reroute can be triggered on the transport LSPs between the PE routers to repair the connection within tens of milliseconds. An egress protection LSP addresses the problem of a node-link failure at the edge of the network (for example, a failure of a PE router).

This example includes the following configuration concepts and statements that are unique to the configuration of an egress protection LSP:

  • context-identifier—Specifies an IPv4 or IPv6 address used to define the pair of PE routers participating in the egress protection LSP. It is assigned to each ordered pair of primary PE and the protector to facilitate protection establishment. This address is globally unique, or unique in the address space of the network where the primary PE and the protector reside.

  • egress-protection—Configures the protector information for the protected Layer 2 circuit and configures the protector Layer 2 circuit at the [edit protocols mpls] hierarchy level. Configures an LSP as an egress protection LSP at the [edit protocols mpls] hierarchy level.

  • protector—Configures the creation of standby pseudowires on the backup PE for link or node protection for the instance.

Figure 1: Egress Protection LSP Configured from Router PE1 to Router PE2
Egress
Protection LSP Configured from Router PE1 to Router PE2

In the event of a failure of the egress PE Router PE1, traffic is switched to the egress protection LSP configured between Router PE1 and Router PE2 (the protector PE router):

  • Device CE2—Traffic origin

  • Router PE3—Ingress PE router

  • Router PE1— (Primary) Egress PE router

  • Router PE2—Protector PE router

  • Device CE1—Traffic destination

When the link between CE1– PE1 goes downs, PE1 will briefly redirect that traffic toward CE1, to PE2. PE2 forwards it to CE1 until ingress router PE3 recalculates to forward the traffic to PE2.

Initially the traffic direction was: CE2 – PE3 – P – PE1 – CE1.

When the link between CE1– PE1 goes down, the traffic will be: CE2 – PE3 – P – PE1 – PE2 –CE1. PE3 then recalculates the path: CE2 – PE3 – P – PE2 – CE1.

This example shows how to configure routers PE1, PE2, and PE3.

Configuration

CLI Quick Configuration

To quickly configure an egress protection LSP, copy the following commands, paste them into a text file, remove any line breaks, change any details necessary to match your network configurations, copy and then paste the commands into the CLI and enter commit from configuration mode.

PE1

PE2

PE3

Step-by-Step Procedure

Step-by-Step Procedure

The following example requires you to navigate various levels in the configuration hierarchy. For information about navigating the CLI, see Using the CLI Editor in Configuration Mode.

To configure an egress protection LSP for router PE1:

  1. Configure RSVP.
  2. Configure MPLS to use the egress protection LSP to protect against a link failure to Device CE1.
  3. Configure BGP.
  4. Configure IS-IS.
  5. Configure LDP.
  6. Configure a load-balancing policy.
  7. Configure the routing options to export routes based on the load-balancing policy.
  8. Configure BGP to advertise nrli from the routing instance with context-ID as next-hop.
  9. Configure l2vpn instance to use the egress LSP configured.
  10. If you are done configuring the device, enter commit from configuration mode.

Step-by-Step Procedure

To configure an egress protection LSP for Router PE2:

  1. Configure RSVP.
  2. Configure MPLS and the LSP that acts as the egress protection LSP.
  3. Configure BGP.
  4. Configure IS-IS.
  5. Configure LDP.
  6. Configure a load-balancing policy.
  7. Configure the routing options to export routes based on the load-balancing policy.
  8. Configure BGP to advertise nrli from the routing instance with context-ID as next-hop.
  9. Configure l2vpn instance to use the egress LSP configured.
  10. If you are done configuring the device, enter commit from configuration mode.

Step-by-Step Procedure

To configure an egress protection LSP for Router PE3:

  1. Configure RSVP.
  2. Configure MPLS.
  3. Configure BGP.
  4. Configure IS-IS.
  5. Configure LDP.
  6. Configure a load-balancing policy.
  7. Configure the routing options to export routes based on the load-balancing policy.
  8. Configure BGP to advertise nlri from the routing instance with context-ID as next-hop.
  9. Configure l2vpn to specify the interface that connects to the site and the remote interface to which you want the specified interface to connect.
  10. If you are done configuring the device, enter commit from configuration.

Results

From configuration mode, confirm your configuration on Router PE1 by entering the show protocols, show policy-options, and show routing-options commands. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.

From configuration mode, confirm your configuration on Router PE2 by entering the show protocols, show policy-options, and show routing-options commands. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.

From configuration mode, confirm your configuration on Router PE3 by entering the show protocols, show policy-options, and show routing-options commands. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.

Verification

Confirm that the configuration is working properly.

Verifying the L2VPN Configuration

Purpose

Verify that LSP is protected by the connection protection logic.

Action

From operational mode, run the show l2vpn connections extensive command.

Meaning

The Egress Protection: Yes output shows that the given PVC is protected by connection protection logic.

Verifying the Routing Instance Details

Purpose

Verify the routing instance information and the context identifier configured on the primary, which is used as the next-hop address in case of node-link failure.

Action

From operational mode, run the show route foo detail command.

Meaning

The context-id is set to 198.51.100.3 and the Vrf-import: [ __vrf-import-foo-internal__] in the output mentions the policy used for rewriting the next-hop address.

Verifying the IS-IS Configuration

Purpose

Verify the IS-IS context identifier information.

Action

From operational mode, run the show isis context-identifier detail command.

Meaning

Router PE2 is the protector and the configured context identifier is in use for the MPLS protocol.

Verifying the MPLS Configuration

Purpose

Verify the context identifier details on the primary and protector PEs.

Action

From operational mode, run the show mpls context-identifier detail command.

Meaning

Context-id is 198.51.100.3, advertise-mode is alias, the MPLS table created for egress protection is __198.51.100.3__.mpls.0, and the egress instance name is foo, which is of type local-l2vpn.

Release History Table
Release
Description
Starting in Junos OS Release 14.2, Junos OS supports the restoration of egress traffic when there is a link or node failure in the egress PE node.