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

[Eric Louie]

I'll just review the configs before they're implemented from now on.
Auto-config seems to be a little too dangerous, and still requires
configuration, which mpls ip does when they add it to both sides.

On Fri, May 1, 2015 at 1:50 PM, Andrew Brant <andrew.brant at me.com> wrote:

>
> 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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