Quick Notes - MPLS Advertise Labels

When using MPLS and restricting what routes have labels ensure to run "no mpls ldp advertise-labels" before adding the restriction. I have seen that if you do not run the command above you will get labels advertised for all routes.

Here is an example:

config>mpls ip
config>no mpls ldp advertise-labels
config>mpls ldp advertise-labels for 10
config>access-list 10 permit 150.8.0.0 0.0.255.255
config-if>mpls ip



Before: "no mpls ldp advertise-labels"

Rack8R4(config)#do sh mpls forwarding
Local Outgoing Prefix Bytes Label Outgoing Next Hop
Label Label or VC or Tunnel Id Switched interface
16 Pop Label 54.8.1.0/24 0 Fa0/1 183.8.46.6
17 17 150.8.1.0/24 0 Se0/0/0 183.8.0.5
No Label 150.8.1.0/24 0 Se0/0/0 183.8.0.3
18 18 150.8.2.0/24 0 Se0/0/0 183.8.0.5
No Label 150.8.2.0/24 0 Se0/0/0 183.8.0.3
19 No Label 150.8.3.3/32 0 Se0/0/0 183.8.0.3
20 Pop Label 150.8.5.5/32 919 Se0/0/0 183.8.0.5
21 Pop Label 150.8.6.6/32 1724 Fa0/1 183.8.46.6
22 22 150.8.7.0/24 0 Se0/0/0 183.8.0.5
No Label 150.8.7.0/24 0 Se0/0/0 183.8.0.3
23 23 150.8.8.0/24 0 Se0/0/0 183.8.0.5
No Label 150.8.8.0/24 0 Se0/0/0 183.8.0.3
24 24 150.8.10.0/24 0 Se0/0/0 183.8.0.5
No Label 150.8.10.0/24 0 Se0/0/0 183.8.0.3
25 Pop Label 183.8.6.0/24 0 Fa0/1 183.8.46.6
26 No Label 183.8.17.0/24 0 Se0/0/0 183.8.0.3
No Label 183.8.17.0/24 0 Se0/0/0 183.8.0.5
27 No Label 183.8.28.0/24 0 Se0/0/0 183.8.0.3
No Label 183.8.28.0/24 0 Se0/0/0 183.8.0.5
28 No Label 183.8.39.0/24 0 Se0/0/0 183.8.0.5
29 No Label 183.8.105.0/24 0 Se0/0/0 183.8.0.3
Local Outgoing Prefix Bytes Label Outgoing Next Hop
Label Label or VC or Tunnel Id Switched interface
No Label 183.8.105.0/24 0 Se0/0/0 183.8.0.5
30 No Label 183.8.107.0/24 0 Se0/0/0 183.8.0.3
No Label 183.8.107.0/24 0 Se0/0/0 183.8.0.5
31 No Label 183.8.123.0/24 0 Se0/0/0 183.8.0.3
No Label 183.8.123.0/24 0 Se0/0/0 183.8.0.5
32 No Label 192.10.8.0/24 0 Se0/0/0 183.8.0.3
33 33 200.0.0.0/24 0 Fa0/1 183.8.46.6
34 34 200.0.1.0/24 0 Fa0/1 183.8.46.6
35 35 200.0.2.0/24 0 Fa0/1 183.8.46.6
36 36 200.0.3.0/24 0 Fa0/1 183.8.46.6
37 No Label 204.12.8.0/24 0 Se0/0/0 183.8.0.5
After: "no mpls ldp advertise-labels" and reapplying "mpls ldp advertise-labels for 10"

Rack8R4(config)#do sh mpls forwarding | ex 150.8
Local Outgoing Prefix Bytes Label Outgoing Next Hop
Label Label or VC or Tunnel Id Switched interface
16 No Label 54.8.1.0/24 0 Fa0/1 183.8.46.6
25 No Label 183.8.6.0/24 0 Fa0/1 183.8.46.6
26 No Label 183.8.17.0/24 0 Se0/0/0 183.8.0.3
No Label 183.8.17.0/24 0 Se0/0/0 183.8.0.5
27 No Label 183.8.28.0/24 0 Se0/0/0 183.8.0.3
No Label 183.8.28.0/24 0 Se0/0/0 183.8.0.5
28 No Label 183.8.39.0/24 0 Se0/0/0 183.8.0.5
29 No Label 183.8.105.0/24 0 Se0/0/0 183.8.0.3
No Label 183.8.105.0/24 0 Se0/0/0 183.8.0.5
30 No Label 183.8.107.0/24 0 Se0/0/0 183.8.0.3
No Label 183.8.107.0/24 0 Se0/0/0 183.8.0.5
31 No Label 183.8.123.0/24 0 Se0/0/0 183.8.0.3
No Label 183.8.123.0/24 0 Se0/0/0 183.8.0.5
32 No Label 192.10.8.0/24 0 Se0/0/0 183.8.0.3
33 No Label 200.0.0.0/24 0 Fa0/1 183.8.46.6
34 No Label 200.0.1.0/24 0 Fa0/1 183.8.46.6
35 No Label 200.0.2.0/24 0 Fa0/1 183.8.46.6
36 No Label 200.0.3.0/24 0 Fa0/1 183.8.46.6
37 No Label 204.12.8.0/24 0 Se0/0/0 183.8.0.5
Rack8R4(config)#do sh mpls forwarding | in 150.8
17 17 150.8.1.0/24 0 Se0/0/0 183.8.0.5
18 18 150.8.2.0/24 0 Se0/0/0 183.8.0.5
20 Pop Label 150.8.5.5/32 1775 Se0/0/0 183.8.0.5
21 Pop Label 150.8.6.6/32 2740 Fa0/1 183.8.46.6
22 22 150.8.7.0/24 0 Se0/0/0 183.8.0.5
23 23 150.8.8.0/24 0 Se0/0/0 183.8.0.5
24 24 150.8.10.0/24 0 Se0/0/0 183.8.0.5