[c-nsp] Packet Lost on interface Loopback

[Rimestad, Steinar]

I have not seen any packet loss on our loopbacks, I have to check with our NOC if they have had any alarms on this, but I guess it would have been escalated already if it had been. Other than the log messages we have not seen any issues yet, but hitting 99%/100% CEF allocation you can be sure to see some strange behavior and find yourself all of a sudden reallocating CEF and reloading all your 7600s.

Although I replied to the %MLSCEF error message, I don’t know if the loopback packet loss is affected by this. It might be an effect of either icmp rate-limiting or CoPP implemented and hitting full allocations there too. Maybe some monitoring system that polls/pings the router too often would be my starting point?

Regards,
Steinar

From: vannara vuth [mailto:vannara1680 at gmail.com]
Sent: 3. mai 2014 09:23
To: Rimestad, Steinar
Cc: dol meun; cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] Packet Lost on interface Loopback

Hi steinar,

I'm also facing the similar issue. What was symtom on your router when receiving the log message? Packet loss to v4 address on loop back as well?

Regards,
Vannara

On Saturday, May 3, 2014, Rimestad, Steinar <Steinar.Rimestad at altibox.no<mailto:Steinar.Rimestad at altibox.no>> wrote:
Hi.

We have been hitting the same issues recently and I am sure several other people on here has as well. Per default the 76xx with untweaked CEF maximum-routes allocation is 512k prefixes for IPv4+MPLS and 256k for IPv6+MC. Seeing as the internet routing table just hit 500k prefixes you should really consider tweaking the cef maximum-routes.

Default:

PE2#show mls cef maximum-routes
FIB TCAM maximum routes :
=======================
Current :-
-------
 IPv4 + MPLS         - 512k (default)
 IPv6 + IP Multicast - 256k (default)

You have to consider your MPLS+MC+IPv6 needs and re-allocate accordingly, we are currently looking to deploy around 700k+ for IPv4 routes as some of our 7600 will live on for a few more years before being replaced.

Best Regards,
Steinar

-----Original Message-----
From: cisco-nsp [mailto:cisco-nsp-bounces at puck.nether.net<javascript:;>] On Behalf Of dol meun
Sent: 3. mai 2014 05:13
To: cisco-nsp at puck.nether.net<javascript:;>
Subject: [c-nsp] Packet Lost on interface Loopback

Dear All,

Has anyone used to meet the problem of packet lost on interface loopback for IPv4 and IPv6 is has no problem in Cisco CISCO7606-S. CPU process is normal 5% to 10%. but we have found the logging "
%MLSCEF-SP-4-FIB_EXCEPTION_THRESHOLD: Hardware CEF entry usage is at 95% capacity for MPLS protocol." but I am not sure it related to the packet lost on the  loopback interface or not. For the ping to the other interface in that router it works fine and traffic pass-through that router also fine.

Pleas help if anyone know that root of that problem.

Best Regards,
Dol
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