This article explains how to map a L2circuit traffic to take a particular RSVP LSP, if there are multiple equal-cost RSVP LSP's available to reach the L2circuit neighbor.

How to map a L2circuit traffic to take a particular RSVP LSP, if there are multiple equal-cost RSVP LSP's available to reach the L2circuit neighbor?

By default, if there are multiple equal-cost RSVP LSPs available to reach the L2Circuit neighbor, one of them will be randomly picked for forwarding. In certain cases, customers would like to use the LSPs for a specific L2circuit traffic; so as to deterministically load-share the traffic in the MPLS core.

To map a L2circuit traffic to a particular LSP, perform the following procedure:

1. Associate a community value, when defining the L2Circuit configuration.


2. Define a policy to match the community value and install the preferred LSP as the nexthop for the matching traffic.


3. Apply this policy under the forwarding-table for the PFE to act upon.

Topology used to demonstrate the configuration:

CE1-PE1-P-PE2-CE2

In the above topology, PE1 and PE2 have two equal-cost RSVP LSPs, which are defined to reach each other. They also form a targeted LDP session to carry the L2Circuit between CE1 and CE2.

The following snapshots are taken in the default mode, without making the changes listed above; that is, both PE1 and PE2 will randomly choose one of the LSPs to carry the L2Circuit traffic.

1. Associate a community value, when defining the L2Circuit configuration:

   lab@PE1# show protocols l2circuit
neighbor 103.103.103.1 {
    interface ge-0/0/3.300 {
        virtual-circuit-id 300;
           community test-community;
    }
}
lab@PE1# show policy-options
community test-community members 300:300;

2. Define a policy to match the community value and install the preferred LSP as the nexthop for the matching traffic:

   lab@PE1# show policy-options
policy-statement mapping-l2ckt-to-lsp {
    term 1 {
        protocol l2circuit;
        from community test-community
}
        then {
            install-nexthop lsp LSP-1;
        }
    }
}

3. Apply this policy under the forwarding-table for the PFE to act upon:

   lab@PE1# show routing-options
forwarding-table {
    export mapping-l2ckt-to-lsp;
}

lab@PE1> show route table mpls.0

mpls.0: 6 destinations, 6 routes (6 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

0 *[MPLS/0] 00:16:01, metric 1
Receive
1 *[MPLS/0] 00:16:01, metric 1
Receive
2 *[MPLS/0] 00:16:01, metric 1
Receive
299808 *[L2CKT/7] 00:16:00
> via ge-0/0/3.300, Pop Offset: 4
ge-0/0/3.300 *[L2CKT/7] 00:16:00, metric2 2
> to 10.10.10.2 via ge-0/0/0.0, label-switched-path LSP-1

lab@PE1> show rsvp session
Ingress RSVP: 2 sessions
To From State Rt Style Labelin Labelout LSPname
103.103.103.1 101.101.101.1 Up 0 1 FF - 300032 LSP-1
103.103.103.1 101.101.101.1 Up 0 1 FF - 300048 LSP-2
Total 2 displayed, Up 2, Down 0

lab@PE1> show route forwarding-table family mpls
Routing table: default.mpls
MPLS:
Destination Type RtRef Next hop Type Index NhRef Netif
default perm 0 dscd 50 1
0 user 0 recv 49 3
1 user 0 recv 49 3
2 user 0 recv 49 3
299808 user 0 Pop 575 2 ge-0/0/3.300
ge-0/0/3.300 (CCC) user 0 indr 262142 2
10.10.10.2 Push 299904, Push 300032(top) 573 3 ge-0/0/0.0

lab@CE1> ping 100.100.100.2 count 500 size 300 rapid
PING 100.100.100.2 (100.100.100.2): 300 data bytes
!!!!!!!!!!!!!!!!!!!!!!!!!!!!
--- 100.100.100.2 ping statistics ---
500 packets transmitted, 500 packets received, 0% packet loss
round-trip min/avg/max/stddev = 0.956/1.170/12.539/1.232 ms

lab@PE1> show mpls lsp statistics
Ingress LSP: 2 sessions
To From State Packets Bytes LSPname
103.103.103.1 101.101.101.1 Up 500 173000 LSP-1
103.103.103.1 101.101.101.1 Up 0 0 LSP-2
Total 2 displayed, Up 2, Down 0

CE1:

lab@CE1> show configuration
## Last commit: 2012-01-06 12:15:43 UTC by lab
interfaces {
    ge-0/3/0 {
        flexible-vlan-tagging;
        unit 300 {
            vlan-id 300;
            family inet {
                address 100.100.100.1/30;
            }
        }
    }
}
lab@CE1>

PE1:

lab@PE1> show configuration
## Last commit: 2012-01-07 12:47:53 UTC by lab
    interfaces {
        ge-0/0/0 {
            unit 0 {
                family inet {
                    address 10.10.10.1/30;
                }
family mpls;
            }
        }
ge-0/0/3 {
    flexible-vlan-tagging;
    encapsulation flexible-ethernet-services;
    unit 300 {
        encapsulation vlan-ccc;
        vlan-id 300;
    }
}
lo0 {
    unit 0 {
        family inet {
            address 101.101.101.1/32
        }
    }
}
}

routing-options {
    forwarding-table {
        export mapping-l2ckt-to-lsp;
    }
}

protocols {
    rsvp {
        interface lo0.0;
        interface ge-0/0/0.0;
    }
mpls {
    label-switched-path LSP-1 {
        from 101.101.101.1;
        to 103.103.103.1;
    }
label-switched-path LSP-2 {
    from 101.101.101.1;
    to 103.103.103.1;
}
interface ge-0/0/0.0;
}
ospf {
    traffic-engineering;
        area 0.0.0.0 {
            interface lo0.0;
            interface ge-0/0/0.0;
        }
    }
ldp {
    interface lo0.0;
}
l2circuit {
    neighbor 103.103.103.1 {
        interface ge-0/0/3.300 {
            virtual-circuit-id 300;
            community test-community;
        }
    }
}
}

policy-options {
    policy-statement mapping-l2ckt-to-lsp {
        term 1 {
            from protocol l2circuit;
            from community test-community;
then {
    install-nexthop lsp LSP-1;
}
        }
}
community test-community members 300:300;
   }

lab@PE1>

P:

lab@P# show
## Last changed: 2012-01-07 10:59:29 UTC
interfaces {
    ge-0/0/1 {
        unit 0 {
            family inet {
                address 10.10.10.2/30;
            }
family mpls;
        }
    }
ge-0/0/2 {
    unit 0 {
        family inet {
            address 20.20.20.1/30;
        }
family mpls;
    }
}
lo0 {
    unit 0 {
        family inet {
            address 104.104.104.1/32;
        }
    }
}
    }
protocols {
    rsvp {
        interface lo0.0;
        interface ge-0/0/1.0;
        interface ge-0/0/2.0;
    }
mpls {
    interface ge-0/0/1.0;
    interface ge-0/0/2.0;
}
ospf {
    traffic-engineering;
        area 0.0.0.0 {
            interface lo0.0;
            interface ge-0/0/1.0;
            interface ge-0/0/2.0;
        }
}
}

[edit]
    lab@P#

PE2:

lab@PE2> show configuration
## Last commit: 1999-01-04 00:26:09 UTC by lab
interfaces {
    ge-0/3/1 {
        Unit 0 {
            family inet {
                address 20.20.20.2/30;
            }
family mpls;
        }
}
ge-0/3/2 {
    flexible-vlan-tagging;
        encapsulation flexible-ethernet-services;
unit 300 {
    encapsulation vlan-ccc;
    vlan-id 300;
}
}
lo0 {
    unit 0 {
        family inet {
            address 103.103.103.1/32;
        }
    }
}
}

routing-options {
    forwarding-table {
        export mapping-l2ckt-to-lsp;
    }
}

protocols {
    rsvp {
        interface ge-0/3/1.0;
        interface lo0.0;
    }
mpls {
    label-switched-path LSP-1 {
        from 103.103.103.1;
        to 101.101.101.1;
    }
label-switched-path LSP-2 {
    from 103.103.103.1;
    to 101.101.101.1;
}
interface ge-0/3/1.0;
}
ospf {
    traffic-engineering;
    area 0.0.0.0 {
    interface lo0.0;
    interface ge-0/3/1.0;
}
}
ldp {
    interface lo0.0;
}
l2circuit {
    neighbor 101.101.101.1 {
        interface ge-0/3/2.300 {
            virtual-circuit-id 300;
            community test-community;
        }
    }
}
}
policy-options {
    policy-statement mapping-l2ckt-to-lsp {
        term 1 {
            from community test-community;
            then {
                install-nexthop lsp LSP-1;
            }
        }
    }
community test-community members 300:300;
}

lab@PE2>

CE2:

lab@CE2# show
## Last changed: 2012-01-06 12:26:25 UTC

interfaces {
    ge-0/2/0 {
        flexible-vlan-tagging;
        unit 300 {
            vlan-id 300;
            family inet {
                address 100.100.100.2/30;
            }
        }
    }
}

[edit]
lab@CE2#