HP 2512 and Cisco 3550 VLAN problems

[Bjorn Tore Paulen]

I have quite a big installation of HP switches. One of our customers use Cisco 3550 as their CPE, thus if the customer is to have 3 VLANs I tag them on port 1, and he receives it on his port 1 (802.1q encapsulation) and everyone is happy. Sometimes though, this fails. I do not run STP and I have turned mcheck off on the interface towards the customer. Some of the Cisco switches keeps blocking the port; not all of them. I wonder if it could have something to do with MAC-addresses - if the Cisco is set to ACCESS instead of TRUNK (untagged instead of tagged) everything is fine.

Anyone else experienced this?

[Bjorn Tore Paulen]

Update; the Cisco does not see the link down at any time, the HP does for like 3 sec. The same time it takes when I for instance switch from 100FDx to Auto on a port.

I 11/26/03 08:53:02 ports: port 1 is now on-line
I 11/26/03 08:57:42 ports: port 1 is now off-line
I 11/26/03 08:57:45 ports: port 1 is now on-line
I 11/26/03 08:58:27 ports: port 1 is now off-line
I 11/26/03 08:58:30 ports: port 1 is now on-line
I 11/26/03 08:59:22 ports: port 1 is now off-line
I 11/26/03 08:59:39 ports: port 1 is now on-line
I 11/26/03 09:00:35 ports: port 1 is now off-line

[Ardon]

Hmmmm ....not 100% sure but 3 second smells like Passive LACP. If the link is toggling, for one reason or the other, Passive LACP will block the link for 3 to 4 seconds looking for an Active LACP partner on the other side. Could you please try to switch off Passive LACP using the following command out of the configuration mode:

Interface all--->Enter---->no lacp

Mind you that this can briefly interrupt network connectivity.

I can not explain as why you do NOT see the problem when setting the Cisco box to ACCESS (I am HP right:-) but I will look it up.

Thanks, Ardon

[Bjorn Tore Paulen]

...oh, and I always use 'no lacp' on my ports.