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New Member

Correct/Incorrect Speed/Duplex for Routers and 5500s

OK - I have this problem in quite a few locations. I have installed MC3810 Routers, connected the E0 interface to a port on a Cat5500 Switch (WS-C5224 Blade), and then the barrage of collisions begin...

I have tried the following:

1. Swap out Patch Cables

2. Change Ports

3. Set Switch Ports to Static 10m 1/2 Duplex

4. Set Switch Ports to Static 10m Full Duplex (gets rid of the collisions, but the Alignment/CRC errors then mount up

Not sure what else I can do... The interfaces on the router are not configurable, and they SHOULD be 10m/Half from the factory...

Like I said, I have this in a few locations (30+) and the amount of collisions are not acceptable (700+ per minute)

Any more ideas would be helpful. I'm not an idiot, nor am I a newbie, but on this one, I feel like both, because it's such an easy sounding thing to solve.

just to show you...

----- -------- --------- ------------- -------- -------- -------- -------

5/1 disabled shutdown 0 0 1 disabled 10

Port Num-Addr Secure-Src-Addr Age-Left Last-Src-Addr Shutdown/Time-Left

----- -------- ----------------- -------- ----------------- ------------------

5/1 0 - - - - -

Port Broadcast-Limit Broadcast-Drop

-------- --------------- --------------

5/1 - 0

Port Align-Err FCS-Err Xmit-Err Rcv-Err UnderSize

----- ---------- ---------- ---------- ---------- ---------

5/1 0 0 0 0 0

Port Single-Col Multi-Coll Late-Coll Excess-Col Carri-Sen Runts Giants

----- ---------- ---------- ---------- ---------- --------- --------- ---------

5/1 86878 47962 0 0 0 0 0



Fri Feb 15 2002, 14:30:38

CCSD-Cat5500: (enable) sh time

Fri Feb 15 2002, 15:19:39 EST


Re: Correct/Incorrect Speed/Duplex for Routers and 5500s

Don't know much about the 3810 but assuming that it is 10 meg/half non configurable then the switch (5500) port should be hardcoded to to match 10/half . Collisions in and of itself is not a bad thing and is normally expected on a half duplex link . If you have a high number of collisions and other errors then you could be overwhelming the port with the amount of traffic you are trying to send down that 10 meg pipe . The acceptable rate is less than 3% errors to input packets aftet that you will notice performance degradation . It sounds like you have eliminated the physical end so I would concentrate more on the traffic type errors and whether it's a utilization problem or what . It may take a protocol analyzer to determine what the problem is .

New Member

Re: Correct/Incorrect Speed/Duplex for Routers and 5500s

Yes, I would agree you looked @ the physical aspect of everything, but now let's look @ IOS aspects. First, you probably have cdp running by default which you probably know advertises itself every 60 seconds and that on top of broadcasts, arps and regular TCP/IP traffic could be contributing to the collision rate. All I'm saying is maybe you can do a no cdp enable command on the routers e0 interface and then of course like the good troubleshooter that you are clear counters and then see if have impacted the situation for the better. Again, you can start @ eliminating cdp and then move on to other protocols maybe the bpdu frames from the switch are causing more traffic? It sounds like you just need to investigate a little bit more and you will probably find out the problem and fix it.

P.S. I have posted another subject on a RSM for a 4006, can anyone help me on that subject.

It's posted by me alonzo-garza



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