[c-nsp] 3750G packet loss

Ed Butler - RapidSwitch ed.butler at rapidswitch.com
Fri Oct 14 13:42:33 EDT 2005


I've investigated the 3750G problem with it dropping packets to its IP
interface as below.

c3750#sh int | i Input queue: [^0]        
  Input queue: 1/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Input queue: 1/75/0/0 (size/max/drops/flushes); Total output drops: 0 

show buffers old dump | in inputtime 
Gives no output

Uptime is 4 weeks.

Further, I ran mtr which was giving approximately 80% loss, and whilst mtr
was pinging the router's IP interface I looked at this interface's packet
stats:
c3750#sh int vlan 211 | i Input queue:
  Input queue: 1/75/147760/0 (size/max/drops/flushes); Total output drops: 0

I am concerned by the significant number of drops it has had. These do not
seem to be incrementing in line with the 80% loss that 'should' be achieved.
In fact, they don't seem to increment at all whilst I sent 20k packets to
the interface of which 4k came back.

Regards,

Ed Butler
RapidSwitch Ltd
DDI: 020 7106 0731

RapidSwitch Ltd, 5th Floor, Sovereign House, 227 Marsh Wall, London, E14 9SD

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-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Saku Ytti
Sent: 14 October 2005 11:04
To: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] 3750G packet loss

On (2005-10-14 10:14 +0100), Ed Butler - RapidSwitch wrote:

> To be clear on this, the 3750s are forwarding traffic 100% correctly 
> with no loss, however they're not dealing with traffic to themselves very
well.
> They're not stressed either, running ~10% CPU usage.
> 
>                   Packets               Pings
>  Host          Loss%   Snt   Last   Avg  Best  Wrst StDev
>  1. cisco3750  81.6%  1227    0.4   0.5   0.3   2.7   0.3
>  2. linuxhost   0.0%  1227    0.2   0.2   0.1  16.2   1.7
> 
> Does anyone have any experience with a similar problem or situation, 
> and can advise how to deal with it?

 3750 has quite agressive defences against the control-plane. You can give
it's control-plane 1.4Mpps of packets and your OSPF/BGP will stay up and it
will forward packets normally.
 So it might be that you have large amount of background traffic towards the
control-plane or then you might have packets stuck in hold-queue. 

 To investigate further please provide:
sh int | i Input queue: [^0]
show buffers old dump | in inputtime
sh ver | i uptime

> 
> Thanks,
> 
> Regards,
> 
> Ed Butler
> RapidSwitch Ltd
> DDI: 020 7106 0731
> 
> RapidSwitch Ltd, 5th Floor, Sovereign House, 227 Marsh Wall, London, 
> E14 9SD
> 
> This email message is intended only for the addressee(s) and contains 
> information that may be confidential and/or copyright.  If you are not 
> the intended recipient please notify the sender by reply email and 
> immediately delete this email. Use, disclosure or reproduction of this 
> email by anyone other than the intended recipient(s) is strictly 
> prohibited. No representation is made that this email or any 
> attachments are free of viruses. Virus scanning is recommended and is 
> the responsibility of the recipient.
> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net 
> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Richard 
> Gallagher
> Sent: 14 October 2005 10:04
> To: Maxim Tuliuk
> Cc: Asbjorn Hojmark - Lists; cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] software upgrade 3750 to 3750 Metro
> 
> From:
> 
> http://www.cisco.com/en/US/products/hw/switches/ps5532/products_data_s
> heet09
> 186a00801eb820.html
> 
> The Enhanced Services ports support enhanced features such as 
> Hierarchical QoS and Traffic Shaping, intelligent 802.1Q tunneling, 
> VLAN translation, MPLS, and EoMPLS. These ports can serve as uplinks 
> to metro aggregation points, including the Cisco Catalyst 4500 and 
> Catalyst 6500 series and the Cisco 7600 Series, and they provide 
> greater intelligence at the network edge.
> 
> The regular cat3750 does not have the same ES ports avialable to 
> enable these extra features.
> 
> HTH, Ric
> 
> Maxim Tuliuk wrote:
> > On Fri, Oct 14, 2005 at 10:26 +0200, Asbjorn Hojmark - Lists wrote:
> >>> Can I do upgrade from 3750 to 3750 Metro?  If yes how?
> >> No.
> >>
> >> The 3750ME has a small PXF router onboard, so it's simply not the 
> >> same hardware.
> > 
> > Is it official or unofficial information? i.e I didn't find about it 
> > on cisco site
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--
  ++ytti
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