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Tunnel Services Overview

 

Tunnel Services Overview

By encapsulating arbitrary packets inside a transport protocol, tunneling provides a private, secure path through an otherwise public network. Tunnels connect discontinuous subnetworks and enable encryption interfaces, virtual private networks (VPNs), and MPLS. If you have a Tunnel Physical Interface Card (PIC) installed in your M Series or T Series router, you can configure unicast, multicast, and logical tunnels.

You can configure two types of tunnels for VPNs: one to facilitate routing table lookups and another to facilitate VPN routing and forwarding instance (VRF) table lookups.

For information about encryption interfaces, see Configuring Encryption Interfaces. For information about VPNs, see the Junos OS VPNs Library for Routing Devices. For information about MPLS, see the MPLS Applications User Guide.

On SRX Series devices, Generic Routing Encapsulation (GRE) and IP-IP tunnels use internal interfaces, gr-0/0/0 and ip-0/0/0, respectively. The Junos OS creates these interfaces at system bootup; they are not associated with physical interfaces.

The Juniper Networks Junos OS supports the tunnel types shown in the following table.

Table 1: Tunnel Interface Types

Interface

Description

gr-0/0/0

Configurable generic routing encapsulation (GRE) interface. GRE allows the encapsulation of one routing protocol over another routing protocol.

Within a router, packets are routed to this internal interface, where they are first encapsulated with a GRE packet and then re-encapsulated with another protocol packet to complete the GRE. The GRE interface is an internal interface only and is not associated with a physical interface. You must configure the interface for it to perform GRE.

gre

Internally generated GRE interface. This interface is generated by the Junos OS to handle GRE. You cannot configure this interface.

ip-0/0/0

Configurable IP-over-IP encapsulation (also called IP tunneling) interface. IP tunneling allows the encapsulation of one IP packet over another IP packet.

Packets are routed to an internal interface where they are encapsulated with an IP packet and then forwarded to the encapsulating packet's destination address. The IP-IP interface is an internal interface only and is not associated with a physical interface. You must configure the interface for it to perform IP tunneling.

ipip

Internally generated IP-over-IP interface. This interface is generated by the Junos OS to handle IP-over-IP encapsulation. It is not a configurable interface.

lt-0/0/0

The lt interface on M Series and T Series routers supports configuration of logical systems—the capability to partition a single physical router into multiple logical devices that perform independent routing tasks.

On SRX Series devices, the lt interface is a configurable logical tunnel interface that interconnects logical systems. See the Junos OS Logical Systems Configuration Guide for Security Devices.

mt-0/0/0

Internally generated multicast tunnel interface. Multicast tunnels filter all unicast packets; if an incoming packet is not destined for a 224/8-or-greater prefix, the packet is dropped and a counter is incremented.

Within a router, packets are routed to this internal interface for multicast filtering. The multicast tunnel interface is an internal interface only and is not associated with a physical interface. If your router has a Tunnel Services PIC, the Junos OS automatically configures one multicast tunnel interface (mt-) for each virtual private network (VPN) you configure. You do not need to configure multicast tunnel interfaces. However, you can configure properties on mt- interfaces, such as the multicast-only statement.

mtun

Internally generated multicast tunnel interface. This interface is generated by the Junos OS to handle multicast tunnel services. It is not a configurable interface.

pd-0/0/0

Configurable Protocol Independent Multicast (PIM) de-encapsulation interface. In PIM sparse mode, the first-hop router encapsulates packets destined for the rendezvous point router. The packets are encapsulated with a unicast header and are forwarded through a unicast tunnel to the rendezvous point. The rendezvous point then de-encapsulates the packets and transmits them through its multicast tree.

Within a router, packets are routed to this internal interface for de-encapsulation. The PIM de-encapsulation interface is an internal interface only and is not associated with a physical interface. You must configure the interface for it to perform PIM de-encapsulation.

Note: On SRX Series devices, this interface type is ppd0.

pe-0/0/0

Configurable PIM encapsulation interface. In PIM sparse mode, the first-hop router encapsulates packets destined for the rendezvous point router. The packets are encapsulated with a unicast header and are forwarded through a unicast tunnel to the rendezvous point. The rendezvous point then de-encapsulates the packets and transmits them through its multicast tree.

Within a router, packets are routed to this internal interface for encapsulation. The PIM encapsulation interface is an internal interface only and is not associated with a physical interface. You must configure the interface for it to perform PIM encapsulation.

Note: On SRX Series devices, this interface type is ppe0.

pimd

Internally generated PIM de-encapsulation interface. This interface is generated by the Junos OS to handle PIM de-encapsulation. It is not a configurable interface.

pime

Internally generated PIM encapsulation interface. This interface is generated by the Junos OS to handle PIM encapsulation. It is not a configurable interface.

vt-0/0/0

Configurable virtual loopback tunnel interface. Facilitates VRF table lookup based on MPLS labels. This interface type is supported on M Series and T Series routers, but not on SRX Series devices.

To configure a virtual loopback tunnel to facilitate VRF table lookup based on MPLS labels, you specify a virtual loopback tunnel interface name and associate it with a routing instance that belongs to a particular routing table. The packet loops back through the virtual loopback tunnel for route lookup.

Starting in Junos OS Release 15.1, you can configure Layer 2 Ethernet services over GRE interfaces (gr-fpc/pic/port to use GRE encapsulation). To enable Layer 2 Ethernet packets to be terminated on GRE tunnels, you must configure the bridge domain protocol family on the gr- interfaces and associate the gr- interfaces with the bridge domain. You must configure the GRE interfaces as core-facing interfaces, and they must be access or trunk interfaces. To configure the bridge domain family on gr- interfaces, include the family bridge statement at the [edit interfaces gr-fpc/pic/port unit logical-unit-number] hierarchy level. To associate the gr- interface with a bridge domain, include the interface gr-fpc/pic/port statement at the [edit routing-instances routing-instance-name bridge-domains bridge-domain-name] hierarchy level. You can associate GRE interfaces in a bridge domain with the corresponding VLAN ID or list of VLAN IDs in a bridge domain by including the vlan-id (all | none | number) statement or the vlan-id-list [ vlan-id-numbers ] statement at the [edit bridge-domains bridge-domain-name] hierarchy level. The VLAN IDs configured for the bridge domain must match with the VLAN IDs that you configure for GRE interfaces by using the vlan-id (all | none | number) statement or the vlan-id-list [ vlan-id-numbers ] statement at the [edit interfaces gr-fpc/pic/port unit logical-unit-number] hierarchy level. You can also configure GRE interfaces within a bridge domain associated with a virtual switch instance. Layer 2 Ethernet packets over GRE tunnels are also supported with the GRE key option. The gre-key match condition allows a user to match against the GRE key field, which is an optional field in GRE encapsulated packets. The key can be matched as a single key value, a range of key values, or both.

Note

Starting in Junos OS Release 16.1, Layer 2 Port mirroring to a remote collector over a GRE interface is supported.

Tunnel Interfaces on MX Series Routers with MPC7E-10G, MPC7E-MRATE, MX2K-MPC8E, and MX2K-MPC9E

MPC7E-10G, MPC7E-MRATE, MX2K-MPC8E, and MX2K-MPC9E support a total of four inline tunnel interfaces per MPC, one per PIC. You can create a set of tunnel interfaces per PIC slot up to a maximum of four slots (from 0 through 3) on MX Series routers with these MPCs. These PICs are referred to as pseudo tunnel PICs. You create tunnel interfaces on MX Series routers with MPC7E-10G, MPC7E-MRATE, MX2K-MPC8E, and MX2K-MPC9E by including the following statements at the [edit chassis] hierarchy level:

Packet Forwarding Engine Mapping and Tunnel Bandwidth for MPC7E-MRATE

The tunnel bandwidth for MPC7E-MRATE is 1–120Gbps with an increment of 1Gbps. However, if you do not specify the bandwidth in the configuration, it is set to 120Gbps.

Table 2 shows the mapping between the tunnel bandwidth and the Packet Forwarding Engines for MPC7-MRATE .

Table 2: Packet Forwarding Engine Mapping and Tunnel Bandwidth for MPC7E-MRATE

Pseudo Tunnel PIC

Maximum Bandwidth per Tunnel PIC

PFE Mapping

Maximum Tunnel Bandwidth per PFE

Maximum PFE Bandwidth

PIC0

120Gbps

PFE0

120Gbps

240Gbps

PIC1

120Gbps

PIC2

120Gbps

PFE1

120Gbps

240Gbps

PIC3

120Gbps

Packet Forwarding Engine Mapping and Tunnel Bandwidth for MPC7E-10G

The tunnel bandwidth for MPC7E-10G is 1–120Gbps with an incrementof 1Gbps However, if you do not specify the bandwidth in the configuration, it is set to 120Gbps.

Table 3 shows the mapping between the tunnel bandwidth and the Packet Forwarding Engines for MPC7E-10G.

Table 3: Packet Forwarding Engine Mapping and Tunnel Bandwidth for MPC7E-10G

Pseudo Tunnel PIC

Maximum Bandwidth per Tunnel PIC

PFE Mapping

Maximum Tunnel Bandwidth per PFE

Maximum PFE Bandwidth

PIC0

120Gbps

PFE0

120Gbps

200Gbps

PIC1

120Gbps

PIC2

120Gbps

PFE1

120Gbps

200Gbps

PIC3

120Gbps

Packet Forwarding Engine Mapping and Tunnel Bandwidth for MX2K-MPC8E

The tunnel bandwidth for MX2K-MPC8E is 1– 120Gbps with an increment of 1Gbps. However, if you do not specify the bandwidth in the configuration, it is set to 120Gbps.

Table 4 shows the mapping between the tunnel bandwidth and the Packet Forwarding Engines for MX2K-MPC8E.

Table 4: Packet Forwarding Engine Mapping and Tunnel Bandwidth for MX2K-MPC8E

Pseudo Tunnel PIC

Maximum Bandwidth per Tunnel PIC

Packet Forwarding Engine Mapping

Maximum Tunnel Bandwidth per PFE

Maximum PFE Bandwidth

PIC0

120Gbps

PFE0

120Gbps

240Gbps

PIC1

120Gbps

PFE1

120Gbps

240Gbps

PIC2

120Gbps

PFE2

120Gbps

240Gbps

PIC3

120Gbps

PFE3

120Gbps

240Gbps

Packet Forwarding Engine Mapping and Tunnel Bandwidth for MX2K-MPC9E

The tunnel bandwidth for MX2K-MPC9E is 1– 200Gbps with an increment of 1Gbps. However, if you do not specify the bandwidth in the configuration, it is set to 200Gbps.

Table 5 shows the mapping between the tunnel bandwidth and the Packet Forwarding Engines for MX2K-MPC9E.

Table 5: Packet Forwarding Engine Mapping and Tunnel Bandwidth for MX2K-MPC9E

Pseudo Tunnel PIC

Maximum Bandwidth per Tunnel PIC

Packet Forwarding Engine Mapping

Maximum Tunnel Bandwidth per PFE

Maximum PFE Bandwidth

PIC0

200Gbps

PFE0

200Gbps

400Gbps

PIC1

200Gbps

PFE1

200Gbps

400Gbps

PIC2

200Gbps

PFE2

200Gbps

400Gbps

PIC3

200Gbps

PFE3

200Gbps

400Gbps

Dynamic Tunnels Overview

A VPN that travels through a non-MPLS network requires a GRE tunnel. This tunnel can be either a static tunnel or a dynamic tunnel. A static tunnel is configured manually between two PE routers. A dynamic tunnel is configured using BGP route resolution.

When a router receives a VPN route that resolves over a BGP next hop that does not have an MPLS path, a GRE tunnel can be created dynamically, allowing the VPN traffic to be forwarded to that route. Only GRE IPv4 tunnels are supported.

To configure a dynamic tunnel between two PE routers, include the dynamic-tunnels statement:

You can configure this statement at the following hierarchy levels:

  • [edit routing-options]

  • [edit routing-instances routing-instance-name routing-options]

  • [edit logical-systems logical-system-name routing-options]

  • [edit logical-systems logical-system-name routing-instances routing-instance-name routing-options]

Release History Table
Release
Description
Starting in Junos OS Release 16.1, Layer 2 Port mirroring to a remote collector over a GRE interface is supported.
Starting in Junos OS Release 15.1, you can configure Layer 2 Ethernet services over GRE interfaces (gr-fpc/pic/port to use GRE encapsulation).