[j-nsp] logging cspf/bandwidth reservation failures

[Danny Vernals]

On Thu, Sep 16, 2010 at 3:40 PM, Mohan Nanduri <mohan.nanduri at gmail.com> wrote:
> There are cases when CSPF computes path for setup but at the time of
> signalling the path BW is no longer available on that path.

These events are pretty rare though. I'd imagine the vast majority of
cases will be CSPF failures.  I've had a quick grep though my logs
(messages and RSVP / MPLS traceoptions ouputs) and can only find a few
instances in the whole network (the earliest being April).
Unfortunately my RSVP logs go back further than MPLS and messages due
to the regularity of updates to the latter 2 so I can't check how this
kind of failure is presented to syslog etc.  I'd imagine it would be
easy to log the generating router in these cases as although ResvErr /
PathErr packets are sent and readdressed hop by hop they do contain
the IP of the originating device as well IIRC.  So if this is the case
you are referring to I can see why it should be easy to implement (if
not implemented already).

>
>
> On Thu, Sep 16, 2010 at 10:29 AM, Danny Vernals <danny.vernals at gmail.com>
> wrote:
>>
>> On Thu, Sep 16, 2010 at 1:31 PM, Mohan Nanduri <mohan.nanduri at gmail.com>
>> wrote:
>> > There was an ER opened a while back to identify the node/interface from
>> > where the requetsed BW is unavailable message is being generated from at
>> > the
>> > head-end to aid better troubleshooting, not sure if it was ever
>> > implemented.
>> >
>> >
>>
>> IIRC all of this is local to the ingress LSR, it is a result of a CSPF
>> calculation failing to find a suitable path rather than a downstream
>> node notifying upstream of a lack of bandwidth on a requested path.
>>
>> When CSPF runs, all links that don't fit the specified constraints are
>> removed and then a simple SPF calculation is performed on the
>> remaining links.  If there is no valid path to the destination found
>> you get the "CSPF: no route to " or "bandwidth unavailable" messages.
>> Presumably the only difference in these messages is what called CSPF
>> (optimize timer expiry for "CSPF: no route to " and auto-bandwidth
>> adjust-interval or overflow for "bandwidth unavailable").
>>
>> To me anyway it seems a non trivial task to equate a CSPF failure to a
>> single link or network element.
>>
>> Cheers!
>>
>> Danny
>>
>> > On Thu, Sep 16, 2010 at 4:36 AM, Danny Vernals <danny.vernals at gmail.com>
>> > wrote:
>> >>
>> >> On Wed, Sep 15, 2010 at 8:50 PM, Richard A Steenbergen
>> >> <ras at e-gerbil.net>
>> >> wrote:
>> >> > Is there a way to syslog a cspf or rsvp bandwidth reservation
>> >> > failure?
>> >> > Maybe I'm just being really blind here, but I can't find a way to do
>> >> > it.
>> >> > You can see these events in the cspf logs if you look at individual
>> >> > LSPs
>> >> > with "show mplslsp NAME detail":
>> >> >
>> >> >   1119 Sep 15 19:32:11.635 CSPF failed: no route toward x.x.x.x[87
>> >> > times]
>> >> >   1118 Sep 15 18:50:14.902 Clear Call: CSPF computation failed
>> >> >   1117 Sep 15 18:50:14.895 Deselected as active
>> >> >   1116 Sep 15 18:50:14.895 x.x.x.x: Requested bandwidth unavailable
>> >> >
>> >> > But this seems like it should be syslog worthy, especially
>> >> > considering
>> >> > it's already sysloging worthless stuff like bandwidth changes by
>> >> > default
>> >> > too. Am I missing a sensible way to do this, or is this just in need
>> >> > of
>> >> > a feature request? Cisco definitely does it:
>> >> >
>> >> > Sep 15 19:40:36.458 UTC: %MPLS_TE-5-LSP: LSP x.x.x.x 20554_1024: Path
>> >> > Error from x.x.x.x: Admission control Failure (code 1, value 2, flag
>> >> >
>> >>
>> >> Not exactly what you're after but you can achieve this kind of
>> >> verbosity with traceoptions.  We have the below on all the time:
>> >>
>> >> dannyv at xxx.xxx> show configuration protocols mpls traceoptions
>> >> file mpls-log size 1m files 10 world-readable;
>> >> flag state;
>> >> flag error;
>> >> flag connection;
>> >>
>> >> dannyv at xxx.xxx> show mpls lsp extensive | grep unavaila
>> >>   8181 Sep 16 07:33:40.487 x.x.x.x Requested bandwidth unavailable:
>> >> re-optimized path
>> >>   8179 Sep 16 07:33:40.487 x.x.x.x: Requested bandwidth unavailable
>> >>
>> >>
>> >> dannyv at xxx.xxx> show log mpls-log | grep unavaila
>> >> Sep 16 07:33:40.487521 mpls lsp LSP-NAME primary x.x.x.x: Requested
>> >> bandwidth unavailable
>> >> Sep 16 07:33:40.487586 mpls lsp LSP-NAME primary x.x.x.x Requested
>> >> bandwidth unavailable: re-optimized path
>> >>
>> >>
>> >> > --
>> >> > Richard A Steenbergen <ras at e-gerbil.net>
>> >> > http://www.e-gerbil.net/ras
>> >> > GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1
>> >> > 2CBC)
>> >> > _______________________________________________
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>> >>
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>
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