SR troubleshooting in IS-IS environment

Useful Commands:

show mpls interface
show isis adjacency
show isis database extensive
show route table inet.3

Network Configuration

Figure 1 depicts our physical topology. Our goal is to verify that PE1 to PE2 LSP is up & running.

Figure 1: Segment Routing Troubleshooting Topology

Basic SR configuration was applied to the devices:

PE1

root@vsrx1-pe1> show configuration interfaces
unit 0 {
   family inet {
       address 1.0.0.65/32;
   }
   family iso {
       address 49.0002.0120.0002.0065.00;
   }
   family mpls;
}

ge-0/0/2 {
   vlan-tagging;
   unit 101 {
       vlan-id 101;
       family inet {
           address 1.0.1.0/31;
       }
       family iso;
       family mpls;
   }
   unit 102 {
       vlan-id 102;
       family inet {
           address 1.0.1.2/31;
       }
       family iso;
       family mpls;
   }
}
root@vsrx1-pe1> show configuration protocols
mpls {
interface all;
   label-history;
}
isis {
   source-packet-routing {
       node-segment ipv4-index 65;
   }
   level 1 disable;
level 2 wide-metrics-only;
}

PE2

root@vsrx2-pe2# show interfaces
lo0 {
   unit 0 {
       family inet {
           address 1.0.0.66/32;
       }
       family iso {
           address 49.0002.0120.0002.0066.00;
       }
       family mpls;
   }
}

ge-0/0/2 {
   vlan-tagging;
   unit 105 {
       vlan-id 105;
       family inet {
           address 1.0.1.9/31;
       }
       family iso;
       family mpls;
   }
   unit 106 {
       vlan-id 106;
       family inet {
           address 1.0.1.11/31;
       }
       family iso;
       family mpls;
   }
}

root@vsrx2-pe2# show protocols
mpls {
   interface ge-0/0/1.0 {
       disable;
   }
   interface fxp0.0 {
       disable;
   }
   interface all;
}
isis {
   source-packet-routing {
       node-segment ipv4-index 66;
   }
   level 1 disable;
   level 2 wide-metrics-only;
interface all {
       point-to-point;
   }
}

P1

root@vsrx3-p1> show configuration interfaces
ge-0/0/1 {
   vlan-tagging;
   unit 101 {
       vlan-id 101;
       family inet {
           address 1.0.1.1/31;
       }
       family iso;
       family mpls;
   }
   unit 103 {
       vlan-id 103;
       family inet {
           address 1.0.1.4/31;
       }
       family iso;
       family mpls;
   }
   unit 104 {
       vlan-id 104;
       family inet {
          address 1.0.1.6/31;
       }
       family iso;
       family mpls;
   }
   unit 107 {
       vlan-id 107;
       family inet {
           address 1.0.1.12/31;
       }
       family iso;
       family mpls;
   }
}
lo0 {
   unit 0 {
       family inet {
           address 1.0.0.1/32;
       }
       family iso {
           address 49.0002.0120.0002.0001.00;
       }
       family mpls;
   }
}

root@vsrx3-p1> show configuration protocols
mpls {
interface all;
}
isis {
   source-packet-routing {
       node-segment ipv4-index 1;
   }
   level 1 disable;
   level 2 wide-metrics-only;
   interface all {
       point-to-point;
   }
}

P2, P3, P4 configuration

The rest of P-devices are configured in a similar way. IPv4 Index ID needs to be unique for every device.

Troubleshooting Commands

Our goal is to ensure that end-to-end MPSL LSP is established between PE1 and PE2 devices

MPLS is enabled on the interfaces

root@vsrx1-pe1> show mpls interface

Interface State Administrative groups (x: extended)

ge-0/0/2.101 Up <none>

ge-0/0/2.102 Up <none>

IS-IS adjacency is established

root@vsrx1-pe1> show isis adjacency
Interface             System         L State       Hold (secs) SNPA
ge-0/0/2.101          vsrx3-p1       2 Up                   21
ge-0/0/2.102         vsrx4-p2       2 Up                   25

IS-IS database contains SR attributes

root@vsrx1-pe1> show isis database vsrx2-pe2.00-00 extensive
IS-IS level 1 link-state database:

IS-IS level 2 link-state database:

vsrx2-pe2.00-00 Sequence: 0x5b, Checksum: 0xc546, Lifetime: 643 secs
IPV4 Index: 66
Node Segment Blocks Advertised:
   Start Index : 0, Size : 4096, Label-Range: [ 800000, 804095 ]
   IS neighbor: vsrx5-p3.00                  Metric:       10
     Two-way fragment: vsrx5-p3.00-00, Two-way first fragment: vsrx5-p3.00-00
     P2P IPv4 Adj-SID: 299808, Weight:   0, Flags: –VL–
   IS neighbor: vsrx6-p4.00                   Metric:       10
     Two-way fragment: vsrx6-p4.00-00, Two-way first fragment: vsrx6-p4.00-00
     P2P IPv4 Adj-SID: 299824, Weight:   0, Flags: –VL–
   IP prefix: 1.0.0.66/32                     Metric:       0 Internal Up
   IP prefix: 1.0.1.8/31                     Metric:       10 Internal Up
IP prefix: 1.0.1.10/31                     Metric:       10 Internal Up

There is a path in inet.3 table

root@vsrx1-pe1> show route 1.0.0.66 table inet.3

inet.3: 5 destinations, 5 routes (5 active, 0 holddown, 0 hidden)
+ = Active Route, – = Last Active, * = Both

1.0.0.66/32       *[L-ISIS/14] 00:53:23, metric 30
                   > to 1.0.1.1 via ge-0/0/2.101, Push 800066
                     to 1.0.1.3 via ge-0/0/2.102, Push 800066

Juniper Segment Routing Troubleshooting commands