Re: IP Fast Reroute - Page 2

patcbr600 · ‎05-16-2009

Hi all,

Can any one tell me if ip fast retoute is suported on cisco 7200/7600

Thanks

Laurent Aubert · ‎06-21-2010

Hi Chintan,

BGP PIC (either Core or Edge) allows you to have a convergence time based only on the IGP or link failure detection for external neighbors having 10 or 300k BGP prefixes.

Your understanding is correct and the implementation is based on a hierarchical FIB. I don't see any restriction between PIC Edge and eiBGP multipath but I never tested it.

If you have a lot of BGP prefixes to converge , the difference with and without this feature is significant.

HTH

Laurent.

chintan-shah · ‎06-21-2010

Hi Laurent,

Thanks for further clarification.

Regards,

Chintan

smailmilak · ‎09-21-2011

Hi,

I am configuring IP FRR for OSPF on IOS-XR 4.0.3. I found some cisco documents and it looks like that IP FRR is working. There are some 7600 RSP 720 with 15.1.3 which supports IP FRR, too.

My question is what are the show commands for IP FRR with OSPF on IOS-XR. I can not find on the router nor on any documents.

There are some show commands fos IP FRR ISIS though-

On IOS 15.1.3 is sh ip ospf fast-reroute (prefix-summary) with the output is really poor. I need more info.

And how can see the reconvergnece time. With ICMP I do not lose any packets with timeout 1, but I would like to see the convergence time.

BFD is used too with the min timers (50msec because of 7600).

Ivan Krimmel · ‎09-21-2011

Hi,

I'd recommend to have a look at this command:

sh mpls traffic-eng fast-reroute database

HTH,

Ivan.

smailmilak · ‎09-21-2011

Hi,

I am not using MPLS TE FRR but IP FRR which is a new feature that does not need MPLS and RSVP signaling.

Laurent Aubert · ‎09-21-2011

Hi,

Simple ping will not help you to have an accurate idea of the convergence time. In your case, the only thing you can say is it takes less than a second.

You need a traffic generator where you control the number of pps transmitted and can check the number of pps received. The higher of pps you transmit the more accurate convergence time you will be able to estimate as the time between 2x packets decrease.

For IP FRR, show route / should give you the backup path. For OSPF you can also try show ospf route backup-path’

HTH

Laurent.

chintan-shah · ‎09-21-2011

Hi,

I agree with Laurent, ICMP is not right way to test.

You need traffic generator with multiple stream may be iMIX + various packet size to take care of all type of traffic.

I have recently tested LFA for IS-IS along with BFD - with 3K IGP prerfix + 400K BGP Internet prefix + 100K VPN prefix together to verify convergance in P-PE link failure for both Internet and VPN traffic. Result was good - less than 1 sec thanks to BGP PIC Core

But I faced one issue where if LFA is not enabled, even with BGP PIC Core and optimized IOS-XR SPF parameter, convergance jumped to 8 sec - I am any way working with my account team on this since issue is not always reproduciable.

But if you intend to have BFD+LFA, that will take care of less than 1 sec for any core link failure on IOS-XR 4.0.3

you may have to see whether your network topology is well enough to take care through per-link LFA or you need per-prefix ( although CPU supposed to be taking here but i didn't see much on 12K).

HTH,

Chintan

smailmilak · ‎09-22-2011

Thank you Laurent for the show command

Without IP FRR

O 10.1.32.4/30, metric 2

10.1.0.6, from 10.255.0.64, via TenGigE0/0/0/1, path-id 2

10.1.0.2, from 10.255.0.64, via TenGigE0/0/0/0, path-id 1

With IP FRR

O 10.1.32.4/30, metric 2

10.1.0.6, from 10.255.0.64, via TenGigE0/0/0/1, path-id 2

Backup path:

10.1.0.2, from 10.255.0.64, via TenGigE0/0/0/0, protected bitmap 0x2

10.1.0.2, from 10.255.0.64, via TenGigE0/0/0/0, path-id 1

Backup path:

10.1.0.10, from 10.255.0.64, via TenGigE0/6/0/0, protected bitmap 0x1

@Chintan-shah

Thank you for the info.

Is there a free packet generator on the web? I know about cisco packet generator but I is not possible to get one.

And what is iMAX? I googled it but could not find out what it is.

Is it possible that you provide me the config for LFA and BGP PIC? Here is my topology. The IGWs and R2 and R4 are CRS router. The others are 7600 RSP 720 with 15.1.3 IOS.

here is an example of my OSPF/IPFRR/BFD config on IOS-XR

router ospf 1

nsr

bfd minimum-interval 50

bfd fast-detect

bfd multiplier 3

mpls ldp sync

mpls ldp auto-config

timers throttle lsa all 0 20 5000

timers throttle spf 24 24 5000

timers lsa min-arrival 20

area 0

bfd minimum-interval 50

bfd fast-detect

bfd multiplier 3

fast-reroute per-link enable

bfd

interface TenGigE0/0/0/0

echo

!

interface TenGigE0/0/0/1

echo

!

interface TenGigE0/1/0/0

echo

!

interface TenGigE0/1/0/1

echo

!

interface TenGigE0/6/0/0

echo

!

echo ipv4 source 10.255.0.1

IOS

router ospf 1

auto-cost reference-bandwidth 10000

fast-reroute per-prefix enable area 0 prefix-priority low

fast-reroute keep-all-paths

timers throttle spf 24 24 5000

timers throttle lsa 0 20 5000

timers lsa arrival 20

interface TenGigabitEthernet1/21

mtu 9164

ip address 10.1.0.6 255.255.255.252

ip ospf hello-interval 1

ip ospf bfd

carrier-delay msec 0

bfd interval 50 min_rx 50 multiplier 3