Distribution Switch not working according to default route

[shoaib sheikh]

Hello All,

I ran into an issue.

User --- acess switch --- Dist Switch ---- Core Switch ---- Firewall ---- Router ---- Internet

Distribution Switch command:

Dist_EB3_EB4#sh run | in ip route 0.0.0.0

ip route 0.0.0.0 0.0.0.0 10.18.88.5

Dist_EB3_EB4#sh ip cef 8.8.8.8
0.0.0.0/0
  nexthop 10.18.88.5 Port-channel252 label 9018

User Machine not able to ping.

ping 8.8.8.8

Pinging 8.8.8.8 with 32 bytes of data:
Request timed out.
Request timed out.
Request timed out.
Request timed out.

Ping statistics for 8.8.8.8:
   Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),

Distribution Switch command:

Dist_EB3_EB4#config t
Enter configuration commands, one per line.  End with CNTL/Z.
Dist_EB3_EB4(config)#ip route 8.8.8.8 255.255.255.255 10.18.88.5
Dist_EB3_EB4(config)#exit

Dist_EB3_EB4#sh ip cef 8.8.8.8
8.8.8.8/32
  nexthop 10.18.88.5 Port-channel252

User Machine able to ping.

ping 8.8.8.8

Pinging 8.8.8.8 with 32 bytes of data:
Reply from 8.8.8.8: bytes=32 time=17ms TTL=54
Reply from 8.8.8.8: bytes=32 time=17ms TTL=54
Reply from 8.8.8.8: bytes=32 time=17ms TTL=54
Reply from 8.8.8.8: bytes=32 time=18ms TTL=54

Ping statistics for 8.8.8.8:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 17ms, Maximum = 18ms, Average = 17ms

The show ip cef has difference of that label 9018 after specific route was placed. But I dont know if this has to do something with LDP.

So to sum up, Distribution Switch ( 6506 in my case and core is 6513 ) is not obeying default route. I know issue is very basic but not able to identify now. 10.18.88.5 is core switch IP .Please help me.

[vivek srivastava]

Seems some issue with TCAM. Pls share below o/p:

sh ip cef 8.8.8.8 detail

sh mls cef 8.8.8.8 detail

sh mls cef ip 8.8.8.8 detail

[shoaib sheikh]

Hello Vivek,

Dist_EB3_EB4#sh run | in ip route 8.8.8.8
ip route 8.8.8.8 255.255.255.255 10.18.88.5
Dist_EB3_EB4#sh ip cef 8.8.8.8 detail
8.8.8.8/32, epoch 25
  local label info: global/2058
  recursive via 10.18.88.5
    attached to Port-channel252

Dist_EB3_EB4#sh mls cef 8.8.8.8 detail
Codes: M - mask entry, V - value entry, A - adjacency index, NR- no_route bit
       LS - load sharing count, RI - router_ip bit, DF: default bit
       CP - copy_to_cpu bit, AS: dest_AS_number, DGTv - dgt_valid bit
       DGT: dgt/others value

Format:IPV4 (valid class vpn   prefix)
M(362    ):   1     F    2FFF 255.255.255.255
V(362    ):   1     0    0    8.8.8.8
                              (A:180230, LS:0, NR:0, RI:0, DF:0 CP:0 DGTv:1, DGT:0)

Dist_EB3_EB4#sh mls cef ip 8.8.8.8 detail
Codes: M - mask entry, V - value entry, A - adjacency index, NR- no_route bit
       LS - load sharing count, RI - router_ip bit, DF: default bit
       CP - copy_to_cpu bit, AS: dest_AS_number, DGTv - dgt_valid bit
       DGT: dgt/others value

Format:IPV4 (valid class vpn   prefix)
M(362    ):   1     F    2FFF 255.255.255.255
V(362    ):   1     0    0    8.8.8.8
                              (A:180230, LS:0, NR:0, RI:0, DF:0 CP:0 DGTv:1, DGT:0)

Dist_EB3_EB4#config t
Enter configuration commands, one per line.  End with CNTL/Z.
Dist_EB3_EB4(config)#no ip route 8.8.8.8 255.255.255.255 10.18.88.5
Dist_EB3_EB4(config)#exit
Dist_EB3_EB4#sh ip cef 8.8.8.8 detail
0.0.0.0/0, epoch 25, flags default route
  recursive via 10.18.88.5
    attached to Port-channel252 label 9018

Dist_EB3_EB4#sh mls cef ip 8.8.8.8 detail
Codes: M - mask entry, V - value entry, A - adjacency index, NR- no_route bit
       LS - load sharing count, RI - router_ip bit, DF: default bit
       CP - copy_to_cpu bit, AS: dest_AS_number, DGTv - dgt_valid bit
       DGT: dgt/others value

Format:IPV4 (valid class vpn   prefix)

Dist_EB3_EB4#sh mls cef ip 8.8.8.8 detail
Codes: M - mask entry, V - value entry, A - adjacency index, NR- no_route bit
       LS - load sharing count, RI - router_ip bit, DF: default bit
       CP - copy_to_cpu bit, AS: dest_AS_number, DGTv - dgt_valid bit
       DGT: dgt/others value

Format:IPV4 (valid class vpn   prefix)

Dist_EB3_EB4#

[vivek srivastava]

What SUP you are using ??

Can you try below in maintanence window:

mls rp ip

ip route 0.0.0.0 0.0.0.0 Port-channel252 10.18.88.5

[shoaib sheikh]

Hello Vivek,

Raised a TAC for the same. Came to know that Core was advertising 9242 label for default route but Distribution was sending with 9018 label (see my first post ).

He did clear ip route 0.0.0.0 0.0.0.0 on Distribution and it received updated label. So this is cef programming issue.

Dist_EB3_EB4#sh ip cef 8.8.8.8
0.0.0.0/0
  nexthop 10.18.88.5 Port-channel252 label 9242

Core Switch:

show mpls ldp bindings 0.0.0.0 0
  lib entry: 0.0.0.0/0, rev 52
        local binding:  label: 9242
        remote binding: lsr: 3.3.3.3:0, label: imp-null

It all happened because I upgraded core switch image last weekend. Thanks for all help Vivek.

[vivek srivastava]

Thanks for the update. Good learning anyways.