12.2 31 SB13 Internet VRF Issue..RCA

Reminiscent 5th February when we faced a issue with SB13 and consequence faced downtime for internet customers. Why I was so upset and working continously on to the problem because the IOS was being tested arduous.

Continued with my previous post of SB 13 internet vrf problem . In this post we are able to know where the problem is. Now waiting for the cisco team how they are going to announce it. The problem was reported first by us to cisco with proper findings and results.


Logs are given below:-

a) Logs taken during that time when the PE was working for both INTERNET vrf and CUST vrf with IOS SB13.
Results:- Customers were not able to access internet.

Command a.1

INTERNET_MPLS#show ip cef vrf INTERNET 0.0.0.0 0.0.0.0 internal
0.0.0.0/0, epoch 0, RIB[S], refcount 6, per-destination sharing
sources: RIB, D/N, DRH
feature space:
LFD: 0.0.0.0/0 1 local label
local label info: other/17
contains path extension list
disposition chain 0x658A91B8
IPRM: 0x00058000
subblocks:
DefNet source: 0.0.0.0/0
ifnums:
FastEthernet0/0(3): 1.1.1.1
path_list contains at least one resolved destination(s). HW not notified
path 64BAF9A4, path list 64BA36B8, share 1/1, type recursive nexthop, for IPv4, flags resolved
MPLS short path extensions: MOI flags = 0x5
recursive via 1.1.1.1[IPv4:Default], fib 64BF6884, 1 terminal fib
path 64BB01E0, path list 64BA4048, share 1/1, type adjacency prefix, for IPv4
attached to FastEthernet0/0, adjacency IP adj out of FastEthernet0/0, addr 1.1.1.1 64E9CFA0
output chain: IP adj out of FastEthernet0/0, addr 1.1.1.1 64E9CFA0

In the above output one can see the value of ifnum: Actually it is showing the outgoing interface with next hop ip address and in Output chain clearly adjacency is showing.


Command a.2

IOS With SB13
INTERNET_MPLS#show ip cef vrf CUST 0.0.0.0 0.0.0.0 internal
0.0.0.0/0, epoch 0, RIB[B], refcount 6, per-destination sharing
sources: RIB, D/N, DRH
feature space:
IPRM: 0x00018000
subblocks:
DefNet source: 0.0.0.0/0
ifnums: (none)
path_list contains at least one resolved destination(s). HW not notified
path 64BAF928, path list 64BA3628, share 1/1, type attached nexthop, for IPv4, flags must-be-labelled
nexthop 1.1.1.1 FastEthernet0/0 unusable: no label, adjacency IP adj out of FastEthernet0/0, addr 1.1.1.1 64E9CFA0
output chain: unresolved


In the above output one can see the value of ifnum: Actually it is showing none which lucidly says that no outgoing interface and in Output chain clearly no adjacency is showing only unresolved is there which means next hop adjacency is unable to built.

This is the primary reason for not working because CUST vrf is not able to know whats its outgoing interface along its adjacency table.
But is the customers direct come in INTERNET vrf then they will work becasue INTERNET vrf is having information of outgoing interface with valid next hop address and adjacency.

So the next time if you are facing the same issues try to use the above mentioned commands.


regards
shivlu jain

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