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100064 *[LDP/9] 5d 01:00:51, metric 1
> via t1-4/0/0.0, Pop
100064(S=0) *[LDP/9] 5d 01:00:51, metric 1
> via t1-4/0/0.0, Pop
100080 *[LDP/9] 5d 01:00:51, metric 1
> via t1-4/0/0.0, Swap 100000
This table is the MPLS label-swapping table and is actually a switching table rather
than a routing table. Instead of a prefix in the first column, you see a label value. In
this output, the first three entries correspond to reserved labels, defined in RFC
3032. These three entries are learned from MPLS (as indicated by [MPLS/0] in the second
column) and are always in the mpls.0 routing table. The remaining three entries
are for incoming labels that MPLS assigns to each upstream neighbor. Label 100064
has two entries because the stack value in the MPLS header can be different in different
packets. In the first entry label, 100064, the S (stack) bit is 1, so this label matches
packets that have only one label on their stacks. The second entry, 100064(S=0), has
the stack bit set to 0 and is used when the stack depth is not 1. That is, it is used
when the packet is carrying more than one label. For both labels, the operation pops
the top label off the stack. The third label, 100080, has a swap operation associated
with it.
You can quickly check all the routes learned from LDP with the show route protocol
ldp command:
aviva@RouterG> show route protocol ldp
inet.0: 12 destinations, 13 routes (12 active, 0 holddown, 0 hidden)
inet.3: 2 destinations, 2 routes (2 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
192.168.16.1/32 *[LDP/9] 1d 23:03:35, metric 1
> via t1-4/0/0.0, Push 100000
192.168.17.1/32 *[LDP/9] 1d 23:03:35, metric 1
> via t1-4/0/0.0
__juniper_private1__.inet.0: 2 destinations, 2 routes (2 active, 0 holddown, 0
hidden)
mpls.0: 6 destinations, 6 routes (6 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
100064 *[LDP/9] 1d 23:03:35, metric 1
> via t1-4/0/0.0, Pop
100064(S=0) *[LDP/9] 1d 23:03:35, metric 1
> via t1-4/0/0.0, Pop
100080 *[LDP/9] 1d 23:03:35, metric 1
> via t1-4/0/0.0, Swap 100000
This output displays the routes for the LDP FECs, stored in inet.3, and the labelswitching
state stored in mpls.0.
Use the show route forwarding-table mpls command to see the active MPLS routes in
the Routing Engine’s forwarding table:
496 | Chapter 14: MPLS
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