Regarding pause frames, there is some extra info on CCO about 7201, which makes it even more interesting by
distinguishing the functionality between the GE ports.
http://www.cisco.com/en/US/docs/routers/7200/install_and_upgrade/7201_install_config/11364a.html#wp1013455
Too bad there isn't a way on these routers (like in switches) to disable
flow-control but keep auto-negotiation on.
--
Tassos
Rodney Dunn wrote on 11/02/2009 16:47:
On Wed, Feb 11, 2009 at 04:26:07PM +0200, Tassos Chatzithomaoglou wrote:
We had a similar case with microbursts and lots of small packets and
after moving to NPE-G2, we're very happy with it.
Traffic goes up, CPU is blocked at 75%, still no sign of drops.
Good to know. It all depends on the load.
The direction forward is hw based forwarding for gige line rate
traffic (ASR1000, 76xx, etc..)
Regarding the pause frames, i'm too very confused about them being
supported.
http://markmail.org/message/y7bjuudmbrfofp6z
I've done some research and there appears to be some issues on
how the MAC chip can account for the pause frames sent/received
although it does appear to support flow control.
But my *opinion* on that is flow control is a wasted effort becaus
you can't quantify the burst and therefore you just buffer on the
other side and risk drops there.
Rodney
--
Tassos
Lars Lystrup Christensen wrote on 11/02/2009 15:47:
Hi John
We had the same issue a few years ago on a Cisco 7204VXR with the
NPE-G1 processor. I believe we were told, that we had hit the max
capacity of the router.
______________________________________
Med venlig hilsen / Kind regards
Lars Lystrup Christensen
Director of Engineering, CCIE(tm) #20292
Danske Telecom A/S
Sundkrogsgade 13, 4
2100 K?benhavn ?
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of john douglas
Sent: 11. februar 2009 14:36
To: [email protected]
Subject: [c-nsp] 7301 NPE-G1 gigabit overruns
Hi All,
I am hoping someone may have some guidance.
We have some 7301 NPE-G1 running 12.2(33)SRC3 connected to Catalyst
3560 switch, dot1q trunking with a few Vlans. I find on the 7301
router whenever I try to drive a given gigabit sub interface beyond
about 200mbps I begin to see Input Errors (Overruns) incrementing on
the physical interface and begin exhibiting packet loss. Under the
show controller information I see rx_overrun and rx_int_drop
incrementing - all other Rx error values under "Statistics" section
are zero. On the switch I see pause input incrementing, but no
errors.
Cpu is 40%.
I have read other postings about this being attributed to microburst
of traffic but I am still a little unclear I am trying to work out
1) Does the G1 correctly support pause frames?
2) Are there any knobs we can tweak - or we simply hitting the limits
of the silicon?
The short term solution has been to spread the vlan sub interfaces
over the 3 gig interfaces however this leaves me in a situation where
I cannot really use EEM to migrate sub interface config from one
gigabit interface to another should there be a failure, as the target
interface will being exhibiting overruns and loss.
Any advice appreciated,
Kind regards,
John
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