[c-nsp] c-delay/pos trig delay/dwdm link with bgp

[Oliver Boehmer (oboehmer)]

hjan <> wrote on Friday, March 09, 2007 7:30 PM:

> Hi all,
> one of our customer have two 7600 with 2XOC48 pos interface connected
> over dwdm protected link.
> 
>  -----                    -----
>>     | <--------------> |     |
>> RA  |                  |  RB |
>>     | <--------------> |     |
>  -----                    -----
> 
> They use bgp over those link, while testing dwdm protection with
> manually issued fault on wdm link, they noticed an up/down of about
> ten second on pos interface.
> I suggest to use *pos delay triggers line n* on link to avoid
> interface up/down as consequence of micro line los triggered by wdm
> protection.

right, you want to tune this timer.. The default of 100 msec should,
however, take care of the short los while protection kicked in? Can you
configure all "pos report" commands on the interface to see what
happens?

> I have some doubt about carrier-delay.
> If a low carrier delay is certain useful with igp i'm not sure it's a
> good choice for bgp.

well, I think you could argue that carrier-delay zero might not be
optimal for directly connected eBGP neighbors as a short failure can
take the neighbor down, so I agree with your scepticism..

But independent of the carrier-delay, you want to prevent micro-failures
to cause a POS failure, because then you'll run into the 10 seconds
up-event timer, so tune the delay triggers..

	oli