VSS Switchport Issue

[John Apricena]

Hello Guys,

I am having an issue withVSS ports that I was hopingyou could assist with. I have a pair of 4500x switch, and VSS is completely configured and working properly, however when I uplink both switches using the same port on both to another switch, I cannot pass traffic between them. I have a trunk port setup on both ends, and vlans on both sides, however traffic doesn't cross the trunks. I have tested these same ports as layer 3 routed ports and they work fine. I uplink directly into my laptop with them using a copper GBIC, but when i connect to another cisco switch, traffic does not pass. Could there be a setting im missing to be configrued on the 4500x switches?

[Jon Marshall]

Can you choose a new port on the switch and then connect the router. Try connecting and then post -

sh int

for both the switchport and the router interface.

Jon

[John Apricena]

I have packed everything up for the day. I will try in a few days, and let you know. Thanks for all your help Jon!

[John Apricena]

Jon,

Could the VSS Configuration have anything to do with it?

[Jon Marshall]

John

Not as far as i can see at the moment. I think it is more to do with the actual GBICs and perhaps the ports not negotiating properly.

I'm not saying it isn't VSS but i can't see how based on what we have discussed.

Jon

[Reza Sharifi]

John,

As Jon noted in his first post, is there a reason for not using an Etherchannel?  One of the benefits of VSS is that when you have a layer-2 switch dually uplinked, you create an Etherchannel and put both uplinks in it, so both links can be used to forward traffic and not just one as when you have 2 separate switches.  With VSS, logically it appears you are connecting one switch to one and not one to 2.

Can you try adding both uplinks on the VSS pair and the layer-2 switch to an Etherchannel using LACP and test again?

HTH

[Jon Marshall · Accepted solution]

John

A thought occured to me after i logged off last night.

The switch is using 100Mbps connections. Is the router doing the same ?

Are the ports on the 4500 you are connecting to capable of running 10/100/1000Mbps connections ?

Jon

[John Apricena]

Hi Reza,thanks for the response. I had setup a L2 port channel, however the same issue were there.

Hi Jon,

Your point about the speed may be the problem. It looks like my transceivers which are GLC-T can only communicate at 1 GB. This would explain why it doesnt work when uplinked into the switch and router, as both are 100 Mb. It worked when in my laptop cause my laptop as a gig NIC. I certainly think this is the problem, and will test with a 1000 gig switch or router, just might have to buy one to test. Thanks again for the input!

[John Apricena]

Hi Jon,

I tested with a gigabit switch, and the ports came up with no issues. The 100 Mb ports were the issue. I wasn't aware that the GBICs would only communicate at 1000 Gb. Thanks for the assistance.