Description

The article provides information on basics of Connecting Logical Systems Using Logical Tunnel Interfaces.

Symptoms

To connect two logical systems, you configure a logical tunnel interface on both logical systems.
Then you configure a peer relationship between the logical tunnel interfaces, thus creating a point-to-point connection.
The feature is available in On M Series, MX Series, and T Series routers .
Tunnel Interface Types:

Description

gr-0/0/0

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

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.


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.


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.

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.

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 Firewalls.
 

Solution

Please follow below Procedure to build logical tunnels which act as virtual interfaces between logical systems.

  • Create the logical systems and interfaces.

To configure a point-to-point connection between two logical systems, configure the logical tunnel interface by including the lt-fpc/pic/port statement
 

  • Logical tunnels use the same Interface name. A unique unit identifier is required on each virtual interface.

  • Use the peer-unit option to connect interfaces together.

 
User@R5_re> show configuration logical-systems
LogicalSystem-1 {
    interfaces {
        lt-0/1/0 {
            unit 101 {
                description "LogicalSystem-2 P2P Interface";
                encapsulation ethernet;
                peer-unit 201;
                family inet {
                    address 20.0.0.1/24;
                }
            }
        }
    }
}
 
 
LogicalSystem-2 {
    interfaces {
        lt-0/1/0 {
            unit 201 {
                description "LogicalSystem-1 P2P Interface";
                encapsulation ethernet;
                peer-unit 101;
                family inet {
                    address 20.0.0.2/24;
                }
            }
        }
    }
}
 

The interface configuration alone is not enough. Trying to ping between interfaces will fail
               

User@R5_re# run ping 20.0.0.2 logical-system LogicalSystem-1 
PING 20.0.0.2 (20.0.0.2): 56 data bytes
ping: sendto: Can't assign requested address
ping: sendto: Can't assign requested address
^C
--- 20.0.0.2 ping statistics ---
2 packets transmitted, 0 packets received, 100% packet loss
 

The tunnel-services option needs to be enabled on the fpc and pic with the proper bandwidth set:

 
chassis {
    fpc 0 {
        pic 1 {
            tunnel-services {
                bandwidth 100g;
            }
        }
    }
}
 
User@R5_re# run ping 20.0.0.2 logical-system LogicalSystem-1   
PING 20.0.0.2 (20.0.0.2): 56 data bytes
64 bytes from 20.0.0.2: icmp_seq=0 ttl=64 time=3.626 ms
64 bytes from 20.0.0.2: icmp_seq=1 ttl=64 time=0.818 ms
64 bytes from 20.0.0.2: icmp_seq=2 ttl=64 time=1.156 ms
^C
--- 20.0.0.2 ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max/stddev = 0.818/1.867/3.626/1.252 ms
 

Modification History

Initial Draft - 06/01/2024

Related Information

Bandwidth-value—Amount of bandwidth in Gbps to reserve for tunnel traffic using tunnel services:

  • On ACX Series routers, the bandwidth values can be 1g or 10g.

  • On MX Series routers, the bandwidth values can be as follows:

    • 1g

    • 10g through 100g in 10 Gbps increments: 10g, 20g, 30g, 40g, 50g, 60g, 70g, 80g, 90g, 100g

    • 100g through 400g in 100 Gbps increments: 100g, 200g, 300g, 400g

  • On T4000 routers, the bandwidth values can be 10g through 100g in 10 Gbps increments: 10g, 20g, 30g, 40g, 50g, 60g, 70g, 80g, 90g, 100g.