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Runts between Catalyst 2950 and 3500?

We recently upgrade one of our aggregation switches from a Catalyst

3524 to 2950T. The new 2950 switch has 7 directly connected switches via 100Mb trunks, and a single Gb trunk to a Cat6000 with MSFC for intervlan routing/switching - here is the output from show cdp neighbors:

Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone

Device ID Local Intrfce Holdtme Capability Platform Port ID TBA04290439(CatalGig 0/1 156 T S WS-C6006 3/7 School-1.sls.bc.cFas 0/22 179 S I WS-C2950T-Gig

0/1 MAS-B.sls.bc.ca Gig 0/2 152 S I WS-C2950T-Gig 0/1 MES-C.sls.bc.ca Fas 0/11 153 T S WS-C3524-XFas 0/24 MDS-B.sls.bc.ca Fas 0/18 153 T S WS-C2924C-Fas 0/22 MES-B.sls.bc.ca Fas 0/12 165 T S WS-C3524-XFas 0/24 MES-A.sls.bc.ca Fas 0/9 177 T S WS-C2924-XFas 0/24 MDS-A.sls.bc.ca Fas 0/19 140 S I WS-C2950T-Gig 0/2

We are now seeing Runts on the two 3524 switches which were not occurring before installing the 2950T (in place of a 3524 with GBIC). We are not seeing any unusual errors on any other links, only those between the 2950T and the two 3524s.

Here is the config for the 2950T ports: interface FastEthernet0/11 description ->MES-C f0/24 switchport mode trunk no ip address ! interface FastEthernet0/12 description ->MES-B f0/24 switchport mode trunk no ip address !

And here is the config for one of the 3524s (they are the same on each)

interface FastEthernet0/24 description ->MAS-A f0/11 switchport trunk encapsulation dot1q switchport trunk pruning vlan none switchport mode trunk !

Of course, in making this change, we had to switch from ISL to dot1q trunking, but this did not cause a problem for the other switches.

The 3500s are running: (C3500XL-C3H2S-M), Version 12.0(5.3)WC(1), MAINTENANCE INTERIM SOFTWARE

The 2950T is running: (C2950-I6Q4L2-M), Version 12.1(13)EA1, RELEASE SOFTWARE (fc1)

We have tried forcing both sides to 100Mb Full with no change in the runts. They appear to negotiate speed/duplex correctly in auto mode.

Here is an example of interface counters on the 3524:

5 minute input rate 2233000 bits/sec, 244 packets/sec 5 minute output rate 121000 bits/sec, 139 packets/sec 485239 packets input, 529056493 bytes Received 55508 broadcasts, 136 runts, 0 giants, 0 throttles 136 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored 0 watchdog, 48305 multicast 0 input packets with dribble condition detected 282790 packets output, 32637835 bytes, 0 underruns 0 output errors, 0 collisions, 0 interface resets 0 babbles, 0 late collision, 0 deferred 0 lost carrier, 0 no carrier 0 output buffer failures, 0 output buffers swapped out

Any ideas?

Reply to
swrightsls
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I dont see your speed or duplex set. Auto detect generally does not work properly. You probably have a duplex mismatch between the switches. Set

100/FULL on both switches each port.

Reply to
jsalminen

Try moving the 3524s to different ports on the 2950T in case you have a bad ASIC on the 2950T

Reply to
Merv

Try moving the 3524s to different ports on the 2950T in case you have a bad ASIC on the 2950T

Reply to
Merv

We have tried it both ways, with duplex/speed auto or forced to

100/full. Auto does negotiate correctly in this case, and there are no collisions. The runts are definitely not a duplex mismatch issue, as we can introduce a mismatch as a test, and see much higher error rates on the order of 5-10% collisions. What we are seeing now is under 1% runts, but it is wreaking havoc with these links, which are quite busy.
Reply to
swrightsls

I will try that next. Here is the output from the 2950T a few minutes after clearing the counters which shows 'single deferred frames' but no other errors:

MAS-A#sh controllers ethernet-controller fastEthernet 0/12

Transmit Receive 251094411 Bytes 27331035 Bytes

212326 Frames 94064 Frames 5395 Multicast frames 0 FCS errors 1305 Broadcast frames 4 Multicast frames 0 Pause frames 98 Broadcast frames 1127 Single defer frames 0 Control frames 0 Multiple defer frames 0 Pause frames 0 1 collision frames 0 Unknown opcode frames 0 2-15 collisions 0 Alignment errors 0 Late collisions 0 Length out of range 0 Excessive collisions 0 Symbol error frames 0 Total collisions 0 False carrier errors 0 Control frames 0 Valid frames, too small 0 VLAN discard frames 0 Valid frames, too large 0 Too old frames 0 Invalid frames, too small 211929 Tagged frames 0 Invalid frames, too large 0 Aborted Tx frames 0 Discarded frames

Transmit and Receive 215 Minimum size frames 67523 65 to 127 byte frames 59859 128 to 255 byte frames 792 256 to 511 byte frames 10164 512 to 1023 byte frames 4779 1024 to 1518 byte frames 163058 1519 to 1522 byte frames

The other end of the link, the 3524 shows no errors at all:

MES-B#sh controllers ethernet-controller f0/24

Transmit Receive 31171078 Bytes 252986790 Bytes 139204 Unicast frames 207631 Unicast frames 6 Multicast frames 5462 Multicast frames 98 Broadcast frames 1323 Broadcast frames 0 Discarded frames 0 No bandwidth frames 0 Too old frames 0 No buffers frames 0 Deferred frames 29 No dest, unicast 0 1 collision frames 0 No dest, multicast 0 2 collision frames 0 No dest, broadcast 0 3 collision frames 0 Alignment errors 0 4 collision frames 0 FCS errors 0 5 collision frames 0 Collision fragments 0 6 collision frames 0 7 collision frames 66 Undersize frames 0 8 collision frames 4937 Minimum size frames 0 9 collision frames 11866 65 to 127 byte frames 0 10 collision frames 30270 128 to 255 byte frames 0 11 collision frames 707 256 to 511 byte frames 0 12 collision frames 8667 512 to 1023 byte frames 0 13 collision frames 157998 1024 to 1518 byte frames 0 14 collision frames 0 Oversize frames 0 15 collision frames 0 Excessive collisions 0 Late collisions

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I haven't seen this before - any ideas?

Reply to
swrightsls

I have done a bit more testing. I have now tried 3 different ports (12,

13 and 23) on the 2950T switch, trunking to port f0/24 on the 3524. In all cases, I saw 'single deferred frames' on the 2950, and runts on the 3524. I then tried another 2950 in the same rack. Same thing. Next, I moved down to an older 2924M-XL in the same rack, and it works perfectly, without errors, and speed is noticeably better. In the course of my checking I found another switch trunked to the 2950 which had 'deferred frames' - this one a 2924. So it appears the 2950Ts may not like certain revisions of the 2924 and 3524s? We have about 40 of the 2924 and 3524, and have never seen a problem. We have added about a dozen 2950Ts, so I hope we are not about to discover another fiasco like the 1900 series!

ps: One could suggest the 2924 and 3524s are at fault, but they continue to work perfectly with one another - until the 2950T came along, there was no problem...

Reply to
swrightsls

I opened a case with Cisco, and this is a known issue with the 2950 running 12.1(13)EA1. I have upgraded, and just need to find some downtime to reload the switch, as I have 500 users relying on this one.

Hopefully this will help someone else...

Reply to
swrightsls

What is the bug id ?

Reply to
Merv

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