topic Re: VLAN issue, MAC address identical in Switches, Hubs, and Modems

VLAN issue, MAC address identical

jeremy hoff — Mon, 20 Jun 2005 20:59:53 GMT

Greetings,
Have Procurve 2848 switch, and am attempting to configure it to attach to our two current VLANs with HP4000/2400 switches. The VLANs are assigned IDs and named "1 LAN" and "2 REMOTE" on all switches, including the 2848.

The 2848 works with the LAN, but attaching the assigned REMOTE ports yields no connection on either VLAN.

I believe I've traced it to the HP 2848 assigning the identical MAC address to both VLANs... however cannot find a method to change the MAC address assigned to the VLAN.

The command WALKMIB ifphysaddress shows the final two entries "ifphysaddress.99" and "ifphysaddress.100" with the same MAC address ending "95 80" -- I believe this should be incremented to "95 82" on the end... but it does not.

I've attempted removing and readding the VLANs to no avail.

All switches are on the latest firmware. The 2848 will be connected to both VLANs by way of SX-GBICs to SX Modules on the 4000M on the other end.

Please advise. Thanks in advance,
-jeremy h.

Re: VLAN issue, MAC address identical

Shiraz Malik — Tue, 21 Jun 2005 00:29:17 GMT

Hi Jeremy,
Would it be possible for you to attach the running configuration of your 2848?
Also try to reset the switch to the factory defaults and try doing the configuration again.
Regards,

Re: VLAN issue, MAC address identical

Kell van Daal — Tue, 21 Jun 2005 03:05:28 GMT

I would like some more info about how the switches are connected. Multiple links, if yes, a trunk? or 2 seperate links?
Also you say no connection on either VLAN. Does this mean within the same VLAN it isn't possible to get connectivity? Or only across VLAN's? And if it is across, what will be routing in your network? The 2848?

That the 2848 assigns the same MAC-address to both VLAN's is expected and correct behaviour.
The 4000M does not support a MAC-address table per VLAN. The 2848 for example does support this. So depending on your extra info, this shortcoming of the 4000M switch could very possibly be your problem.

Re: VLAN issue, MAC address identical

jeremy hoff — Tue, 21 Jun 2005 09:04:30 GMT

Kell wrote: I would like some more info about how the switches are connected. Multiple links, if yes, a trunk? or 2 seperate links?

Jeremy replies: the two switches are connected with multiple (two) links, one for each VLAN. Not a trunk.

Kell wrote: Also you say no connection on either VLAN. Does this mean within the same VLAN it isn't possible to get connectivity? Or only across VLAN's? And if it is across, what will be routing in your network? The 2848?

Jeremy replies: upon connection of the second fiber (to connect the second VLAN) connectivity from switch to switch ceases.

Kell wrote: That the 2848 assigns the same MAC-address to both VLAN's is expected and correct behaviour.
The 4000M does not support a MAC-address table per VLAN. The 2848 for example does support this. So depending on your extra info, this shortcoming of the 4000M switch could very possibly be your problem.

Jeremy replies: this sounds like the issue at hand. The 4000M does assign a new MAC address for each VLAN. I wonder why the change in policy for the new switches?

Shiraz wrote: Would it be possible for you to attach the running configuration of your 2848?
Also try to reset the switch to the factory defaults and try doing the configuration again.

Jeremy replies: sounds like the 4000M switch is the issue.

Thanks for the help. If there are workarounds other than more hardware I'm listening. :-)

-jeremy h.

Re: VLAN issue, MAC address identical

Ralph Bean_2 — Tue, 21 Jun 2005 10:54:47 GMT

Jeremy -

Please see the FAQ at http://tinyurl.com/ctjl3.

Ralph

Re: VLAN issue, MAC address identical

Ralph Bean_2 — Tue, 21 Jun 2005 13:40:30 GMT

If you click on the tinyurl that I provided it does not appear to work correctly, apparently due to the period immediately after it. If you run into that problem then copy and paste the tinyurl into your browser's URL/Address field without the period.

Ralph

Re: VLAN issue, MAC address identical

jeremy hoff — Tue, 21 Jun 2005 13:57:47 GMT

Thanks for the faq. Tagged VLANs do the trick!

-jeremy h.