[c-nsp] Fast IGP on 6500 & gigE

[Phil Mayers]

All,

Given a mix of 6748-SFP, 6704 and 6716 linecards, with SXI software, and 
OSPF over SVIs, what are people successfully using to speed up link loss 
and subsequent IGP convergence?

Our config broadly looks like:

int Vlan38xx
   description p2p to another router
   ip address 192.168.0.2 255.255.255.254
   ip ospf network point-to-point

int Te1/1
   switchport
   switchport mode trunk
   switchport trunk native vlan 38xx

router ospf 1
   ispf
   nsf
   network 192.168.0.0 0.0.0.255

...and then the various LDP & BGP configs on top. I'm assuming I want 
some combination of:

  1. debounce / carrier-delay (what's the difference) on the gigE
  2. IP event dampening on the SVI
  3. faster timers on the SFP process; possibly as a conservative start:

timers throttle spf 10 100 5000
timers throttle lsa all 10 100 5000
timers lsa arrival 80

The idea is that most routers are dual-attached, so I just want to 
underlying IGP to converge quickly. I'll tackle the LDP and BGP later...

I'm not able to use BFD (since it doesn't work on SVIs under SXI) and 
I'm only worried about physical link-down - we don't have any weird 
layer2 between routers except in a few out-of-the way places, and they 
can just suffer.

I realise some of these answers are "it depends" on the size of your 
network; there are ~25 routers participating in the OSPF, all reasonably 
recent and modern, it's a single area 0 design, and it has ~58 p2p & 
loopbacks (via router LSAs) another 18 E2 routes.

It seems to take ~6msec for an OSPF adjacency to form between two 
routers, almost all of which is in INIT->2WAY so I'm guessing SPF is 
going to be pretty quick.

Suggestions welcome, although "ask Cisco to tell you" is less helpful; 
I'd like to have some independent understanding of how we arrived at the 
numbers, and be able to repeat the process in future ;o)