[c-nsp] MPLS interface continuity and OSPF configuration ME-3600X

[Andrew Brant]

http://www.cisco.com/c/en/us/td/docs/switches/datacenter/sw/5_x/nx-os/mpls/configuration/guide/mpls_cg/mp_ldp_autoconfig.html

I'd look into enabling the OSPF LDP auto-config feature to prevent another NOC induced outage

Sent from my iPhone

> On May 1, 2015, at 14:09, Eric Louie <elouie at techintegrity.com> wrote:
> 
> I had a strange anomaly happen yesterday
> 
> We have 2 ME-3600's as part of an MPLS network.  There are MPLS interfaces
> on both sides of them and between them.  so, like this
> 
> R1 ---- R2 ---- R3 ---- R4
> 
> and all the links between are MPLS IP
> 
> My NOC enabled a new circuit between R2 and R3, and "forgot" to use mpls ip
> on both interfaces.  When they decreased the OSPF cost on the two
> interfaces (as the preferred route), traffic from R1 to R4 stopped at R2.
> (I didn't get the corresponding result R4 to R1, but our monitoring server
> is behind R4, and could not reach any devices connected to R1)  The old
> MPLS circuit was still connected and enabled, just costed out via OSPF.
> 
> So, it "appears" that when the new link was costed in, because it was not
> an MPLS link, the traffic didn't know how to get through the new R2-R3
> link, since the MPLS link was now costed out by MPLS.
> 
> making the new link an MPLS link solved the problem.
> 
> My questions are:
> Is this "by design"?  In other words, if we have MPLS links on both sides
> of a pair of routers, does that MPLS configuration need to be contiguous
> throughout?
> 
> Is this a condition of configuring MPLS, that all intermediate paths need
> to be either tunnelled or configured?  (something that I might have missed
> in my MPLS learning)
> 
> Did we run into a bug?  IOS 15.2(4)S
> 
> Is this a TAC question?
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