[c-nsp] overruns on a gig-e circuit?

[Lasher, Donn]

Unfortunately, most backbone links, at least at a service provider level,
require thinks like MPLS & ACL's, unless you're tunnel-heavy. In our case,
they died a whole lot sooner.



-----Original Message-----
From: John van Oppen [mailto:john at vanoppen.com] 
Sent: Friday, September 07, 2007 9:27 AM
To: Lasher, Donn; cisco-nsp at puck.nether.net
Subject: RE: [c-nsp] overruns on a gig-e circuit?

The other alternative is to turn off all the ACLs on the card, which may
be ok depending on your situation (ie an internal backbone link).    I
did some testing and with the current full table engine 2 cards are at
about 1/3 of the FIB capacity (according to the cef stats on the card)
if all other features are disabled (MPLS and hardware ACLs):


gsr#show ip cef res
Hardware resource allocation status summary
Green (Normal), Yellow (Caution) Red (Alarm)
Slot HW Resource Name        Util     Alert
2    E2_Rx_PLU                23        G
2    E2_Rx_TLU                24        G
3    E2_Rx_PLU                23        G
3    E2_Rx_TLU                24        G




-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Lasher, Donn
Sent: Friday, September 07, 2007 9:08 AM
To: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] overruns on a gig-e circuit?


Engine2 cards have some serious FIB hardware limitations:


Summary of Limitations:
-----------------------

Recent ehancements to the ACL software have increased the memory
required to
store the forwarding table on Engine 2 LCs. The extent of the limitation
depends on which ACL configuration is used. If ACL packet filters are
not
configured on an interface, the input ACL limitation applies.

The 4 port OC12 POS, 1 port OC48 POS, and 3 port GigE LCs can support up
to
448 lines of ACLs in hardware. The configuration of an input ACL on
these
cards will result in a limitation of 171,000 routes. The configuration
of an output ACL on any interface in the router will result in a route
limit of 110,000 for these cards.

The 16 port OC3 POS and 4 port OC12 ATM LCs can support up to
128 lines of ACLs in hardware. The configuration of an input ACL on
these
cards will result in a route limitation of 205,000 routes. The
configuration
of an output ACL on any interface in the router will result in a route
limit of 190,000 for these cards.


With the current route table at well over 200k routes, engine2 cards run
out
of memory and crash if used on a router with full BGP tables.




-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Drew Weaver
Sent: Friday, September 07, 2007 7:53 AM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] overruns on a gig-e circuit?

Hi,

I just replaced a link between two GSR 12000s using old engine 1 cards
with
shiny new engine 2 cards.

The old Engine 1 cards didn't display any "overruns"

But the new engine 2 cards are displaying "overruns"

Example:

Router-A

186 input errors, 0 CRC, 0 frame, 186 overrun, 0 ignored

Router-B

236 input errors, 0 CRC, 0 frame, 236 overrun, 0 ignored

Granted, there are only "236" overruns per each 100million packets but
before we weren't seeing any,

Anyone have any thoughts?

Thanks,
-Drew

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