[c-nsp] OSPF per-prefix LFA

[Mohammad Khalil]

That is what made me ask :) Because I have changed the vlaues to 1/4 (without BFD) as configuring BFD on GNS3 will crash my routers as you know
The same expected failover was 4-5 seconds even after adjusting hello/dead timers !

> Date: Thu, 28 May 2015 13:01:17 +0100
> From: nick at foobar.org
> To: eng_mssk at hotmail.com; cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] OSPF per-prefix LFA
> 
> changing the hello-time should affect failover time in your test
> environment.  Did you test this?  e.g. compare 1s/4s vs 10s/40s.
> 
> Nick
> 
> On 28/05/2015 12:58, Mohammad Khalil wrote:
> > Ok , Sorry I misunderstood
> > So , I think combining both BFD and LFA will do the required failover time
> > But why changing the hello-time on both interfaces (the link between R1 and
> > R2) will not affect ?
> > 
> > BR,
> > Mohammad
> > 
> >> Date: Thu, 28 May 2015 12:53:35 +0100
> >> From: nick at foobar.org
> >> To: eng_mssk at hotmail.com; cisco-nsp at puck.nether.net
> >> Subject: Re: [c-nsp] OSPF per-prefix LFA
> >>
> >> This has nothing to do with OSPF virtual links. I'm talking about the
> >> virtual ethernet interfaces defined in your virtual lab.
> >>
> >> You can test out whether it's doing what I suggested by changing the
> >> hellotime value on the relevant interfaces.
> >>
> >> Nick
> >>
> >> On 28/05/2015 12:50, Mohammad Khalil wrote:
> >> > Hi Nick and thanks for the reply
> >> > All my routers are participating in area 0 , no virtual-link in place
> >> > I shutdown the interface connected to R2 (from CSR or R1 side)
> >> >
> >> > BR,
> >> > Mohammad
> >> >
> >> >> Date: Thu, 28 May 2015 12:36:50 +0100
> >> >> From: nick at foobar.org
> >> >> To: eng_mssk at hotmail.com; cisco-nsp at puck.nether.net
> >> >> Subject: Re: [c-nsp] OSPF per-prefix LFA
> >> >>
> >> >> On 28/05/2015 12:24, Mohammad Khalil wrote:
> >> >> > When I shutdown the interface with R2 (as I do not want to turn off the
> >> >> > remote interface on R2 as I cannot turn on BFD on GNS3) and I have
> >> >> > checked the route to 2.2.2.2 , it took about 5-6 seconds to install the
> >> >> > same route via the backup path (via R3)
> >> >>
> >> >> did you try this by shutting down both sides of the virtual link at the
> >> >> same time? The remote side will not detect carrier loss on a virtual link,
> >> >> so ospf failover will be detected by according to the ospf deadtime.
> >> >>
> >> >> If you handle this with bfd, the failover time should be much faster. Last
> >> >> time I measured this (me3600/100ms bfd), the failover time for l2vpn lsp
> >> >> rerouting was reliably less than 400ms. I.e. the failover for regular ip
> >> >> service should be a little less.
> >> >>
> >> >> Nick
> >>
>