[c-nsp] NCS-5001 - MPLS L3VPN Issue

Adam Vitkovsky Adam.Vitkovsky at gamma.co.uk
Wed Feb 3 08:16:21 EST 2016

Hi James,

> James Bensley
> Sent: Tuesday, February 02, 2016 3:33 PM
> On 2 February 2016 at 15:09, Adam Vitkovsky
> <Adam.Vitkovsky at gamma.co.uk> wrote:
> > Are you running 5+ by any chance?
> >
> >> It’s been years since IOS-XR was released on ASR9000's, no excuse now
> >> for basic features still not working. The TAC responses aren’t
> >> helpful either;
> >
> > I'm sorry to hear that as I have very positive experiences solving cases with
> XR team in Europe.
> > And if the guy on the line did not know how to solve some hardcore
> problem he would get me the SME, a gentleman who designed the particular
> technology on XR so we could have a private techtorial for couple of hours to
> get it solved.
> So TAC responses for "something is broken we need help" is good, config
> issues great, XR TAC is way better than "regular" TAC IMO. I'm talking about
> fresh new bugs. TAC look, agree its a bug, it has to get punted to the BU, now
> the pace of help slows way down because even if the TAC case is a P1
> whatever BU has been roped in seems ignorant of any sense of priority.
I see, yeah that part is tricky as it depends on who do you know in Cisco and/or how big you are.

> >> things like "running an Inter-AS MPLS Option B and BGP-LU at the same
> >> time is not supported" - So we can have labelled VPN routes, or
> >> labelled GRT routes but not both? In this day and age! Someone once
> >> said to us “Inter-AS MPLS Opt C isn’t supported at all” - which we
> >> were running on the PE/ASBR under investigation. We’ve had bucket
> >> loads of issues/TAC cases (we are still opening TAC cases at a decent rate).
> > That's striking.
> It's ridiculous is what it is.
> > I don't know about that as I have been running labelled-unicast and vpnv4
> AFs in the lab just fine.
> > So which part of the Inter-AS MPLS OptC is not supposed to work according
> to TAC please?
> I think actually the problelm was we were running OptC and Opt B (so LU
> path between RRs and VPNv4 between ASBRs, basically migrating from one
> option to the other in a stagged approach). During this period we had some
> issues that are still present after the migration I believe (most label recycling
> issues).
I see I haven't done B to C migration so I can't fully appreciate all the corner cases one might run into.

> Label recycling issues, lets talk about that. Jesus christ I've seen alot of
> those.TAC don't seem to be able to replicate it however we've had it on two
> seperate networks both times as soon as we lifted the boxes off 4.3.4
> default to 4.3.4 + latest SP and the boxes are running Inter-AS OptB. I'm now
> building a lab to try and reliably replicate it for me self so I can kick TAC's arse
> into fixing it.
I've seen couple of HW programing bugs but didn't came across this one as far as I remember.

> Any routers running 4.3.4 default, as soon as they were lifted off default to
> SP4/6/8/10 they have all encountered some form of bug, every time (BGP
> processes stuck at 50% CPU, label recycling errors, line cards rebooting etc).
Yeah I don't like Service Packs, I think it's better to cherry pick only SMUs that are relevant to bugs that you might run into.
And there's always a danger of reintroduction of bugs e.g. a SMU fixes recent bug but reintroduces bug that was fixed by some older SMU.

> 5.1.3 + latest SP is most stable we have found. Once some routers came with
> 5.1.2 out of the box which we would 5.1.3 once they were deployed in the
> DC (once they were racked etc, whereas we would normally upgrade pre-
> shipping to DC) we had some PHY bugs with a WDWM mux. Not to mention
> we hit that famous SSH bug on those too with SSH crashing.
> > My stance on this is that I'd beaten the kit to death in the lab anyways
> before deployment so even if Cisco would swear there are no bug I'd do my
> own scrutiny.
> > On the other hand having to report elemental bugs sucks. But is it the case
> on x.x.3 or x.x.4 version of the code please or was I just lucky or ignorant?
> What we often hear from TAC is "$this feature is supported and so is $that
> feature, but $this and $that together is not" - they are good in that they will
> and look into the problem anyway however telling us that $this + $that is not
> support on the same box makes them not usable for their intended market?!
Well if it's something crucial and was covered in RFP you can claim your money back.


        Adam Vitkovsky
        IP Engineer

T:      0333 006 5936
E:      Adam.Vitkovsky at gamma.co.uk
W:      www.gamma.co.uk

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