[c-nsp] CRC errors on multiple ports of WS-C2950T-48-SI switch
Martin T
m4rtntns at gmail.com
Thu Oct 15 05:41:51 EDT 2015
WS-C2950T-48-SI runs only few short startup tests, but those are passed:
POST: System Board Test : Passed
POST: Ethernet Controller Test : Passed
ASIC Initialization Passed
regards,
Martin
On 10/14/15, Steve Mikulasik <Steve.Mikulasik at civeo.com> wrote:
> When it boots up check to see if the switch passes the startup tests.
>
>
> -----Original Message-----
> From: cisco-nsp [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of
> Martin T
> Sent: Wednesday, October 14, 2015 9:15 AM
> To: cisco-nsp at puck.nether.net
> Subject: [c-nsp] CRC errors on multiple ports of WS-C2950T-48-SI switch
>
> Hi,
>
> I had two WS-C2950T-48-SI switches in the network which all of the sudden
> started to show large amount of CRC errors on about dozen ports. Those two
> incidents are not related to each other, i.e those two incidents did not
> happen at the same time or in the same location.
> I simply received those switches now from remote sites. Unfortunately this
> is all the information I have about the incidents. My first thought was that
> maybe it has to do with the fact that switch has 48 ports and there was
> increased bandwidth between the ports behind different ASICs. I made a
> following physical setup:
>
> Fa0/1 <-> Fa0/48
> Fa0/2 <-> Fa0/47
> Fa0/3 <-> Fa0/46
> ...
> Fa0/24 <-> Fa0/25
>
> Image of the setup can be seen here:
> http://s15.postimg.org/fmsj753qz/WS_C2950_T_48_SI_test_setup.png
>
>
> VLANs were configured like this:
>
> WS-C2950T-48-SI#sh int status
>
> Port Name Status Vlan Duplex Speed Type
> Fa0/1 connected 1 a-full a-100
> 10/100BaseTX
> Fa0/2 connected 2 a-full a-100
> 10/100BaseTX
> Fa0/3 connected 3 a-full a-100
> 10/100BaseTX
> Fa0/4 connected 4 a-full a-100
> 10/100BaseTX
> Fa0/5 connected 5 a-full a-100
> 10/100BaseTX
> Fa0/6 connected 6 a-full a-100
> 10/100BaseTX
> Fa0/7 connected 7 a-full a-100
> 10/100BaseTX
> Fa0/8 connected 8 a-full a-100
> 10/100BaseTX
> Fa0/9 connected 9 a-full a-100
> 10/100BaseTX
> Fa0/10 connected 10 a-full a-100
> 10/100BaseTX
> Fa0/11 connected 11 a-full a-100
> 10/100BaseTX
> Fa0/12 connected 12 a-full a-100
> 10/100BaseTX
> Fa0/13 connected 13 a-full a-100
> 10/100BaseTX
> Fa0/14 connected 14 a-full a-100
> 10/100BaseTX
> Fa0/15 connected 15 a-full a-100
> 10/100BaseTX
> Fa0/16 connected 16 a-full a-100
> 10/100BaseTX
> Fa0/17 connected 17 a-full a-100
> 10/100BaseTX
> Fa0/18 connected 18 a-full a-100
> 10/100BaseTX
> Fa0/19 connected 19 a-full a-100
> 10/100BaseTX
> Fa0/20 connected 20 a-full a-100
> 10/100BaseTX
> Fa0/21 connected 21 a-full a-100
> 10/100BaseTX
> Fa0/22 connected 22 a-full a-100
> 10/100BaseTX
> Fa0/23 connected 23 a-full a-100
> 10/100BaseTX
> Fa0/24 connected 24 a-full a-100
> 10/100BaseTX
> Fa0/25 connected 25 a-full a-100
> 10/100BaseTX
> Fa0/26 connected 24 a-full a-100
> 10/100BaseTX
> Fa0/27 connected 23 a-full a-100
> 10/100BaseTX
> Fa0/28 connected 22 a-full a-100
> 10/100BaseTX
> Fa0/29 connected 21 a-full a-100
> 10/100BaseTX
> Fa0/30 connected 20 a-full a-100
> 10/100BaseTX
> Fa0/31 connected 19 a-full a-100
> 10/100BaseTX
> Fa0/32 connected 18 a-full a-100
> 10/100BaseTX
> Fa0/33 connected 17 a-full a-100
> 10/100BaseTX
> Fa0/34 connected 16 a-full a-100
> 10/100BaseTX
> Fa0/35 connected 15 a-full a-100
> 10/100BaseTX
> Fa0/36 connected 14 a-full a-100
> 10/100BaseTX
> Fa0/37 connected 13 a-full a-100
> 10/100BaseTX
> Fa0/38 connected 12 a-full a-100
> 10/100BaseTX
> Fa0/39 connected 11 a-full a-100
> 10/100BaseTX
> Fa0/40 connected 10 a-full a-100
> 10/100BaseTX
> Fa0/41 connected 9 a-full a-100
> 10/100BaseTX
> Fa0/42 connected 8 a-full a-100
> 10/100BaseTX
> Fa0/43 connected 7 a-full a-100
> 10/100BaseTX
> Fa0/44 connected 6 a-full a-100
> 10/100BaseTX
> Fa0/45 connected 5 a-full a-100
> 10/100BaseTX
> Fa0/46 connected 4 a-full a-100
> 10/100BaseTX
> Fa0/47 connected 3 a-full a-100
> 10/100BaseTX
> Fa0/48 connected 2 a-full a-100
> 10/100BaseTX
> Gi0/1 connected 1 a-full a-1000
> 10/100/1000BaseTX
> Gi0/2 connected 25 a-full a-1000
> 10/100/1000BaseTX
> WS-C2950T-48-SI#
>
>
> While I don't know the internal architecture of WS-C2950T-48-SI switch and
> it has no "sh platform" command which might reveal anything, then at least
> based on traces on the PCB first half of the ports seem to be connected to
> first Broadcom BCM5649B0KPB ASIC and second half of the ports seem to be
> connected to second Broadcom BCM5649B0KPB ASIC. Now if I send 100Mbps of
> traffic through all the switch ports, then there are frame drops because of
> ingress buffer overflow, but no CRC errors.
> In addition, if I decrease bandwidth to 70Mbps, then there are no more
> ingress buffer drops. Last but not least, those two switches served fairly
> low-speed connections and most of the traffic was between FastEthernet and
> GigE uplink-ports.
>
> What might cause vast amount of transient CRC errors on multiple switch
> ports? Maybe the PCB of WS-C2950T-48-SI switch is known to be especially
> receptive to EMI? Any other ideas?
>
>
>
> thanks,
> Martin
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