[c-nsp] 7301 NPE-G1 gigabit overruns

[Tassos Chatzithomaoglou]

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: cisco-nsp-bounces at puck.nether.net 
>>> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of john douglas
>>> Sent: 11. februar 2009 14:36
>>> To: cisco-nsp at puck.nether.net
>>> 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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