Any Cisco switch/IOS Gurus here?

[kod3001]

that would suggest that frames tagged to be in vlan1 aren't getting over the trunk to the 3com, hmmm.

Therefore...

mmm...
ahh, I wonder if, because vlan 1 is the default native vlan on Cisco, 3com is not doing anything with it. I wonder if thats why Cisco set the native vlan to 2 ?

perhaps try setting the native vlan on g0/17 to something well out of the way - vlan 20.

 

[omslaw]

OK, let me try that and get back...

 

[kod3001]

while you're at it, rule out spanning-tree, your cisco switch's bridge priority will probably be 8192 at the moment.

at global type
spanning-tree uplinkfast

that'll set the bridge priority to 48192

 

[gsferrari]

n00b Questions:

* Can the native VLAN be changed from vlan1 to vlan2? From what i remember...this is not possible. Dot1Q standard is to ignore frames in Vlan1 and Vlan1 only.

If this is the case - and if the 3COM is expecting all frames to be tagged...maybe the solution is to do away with vlan1 entirely. Start the vlans from Vlan2 through Vlan15 instead of vlan1 through vlan14.

Or am I missing the point here?

 

[kod3001]

n00b Questions:

* Can the native VLAN be changed from vlan1 to vlan2? From what i remember...this is not possible. Dot1Q standard is to ignore frames in Vlan1 and Vlan1 only.

If this is the case - and if the 3COM is expecting all frames to be tagged...maybe the solution is to do away with vlan1 entirely. Start the vlans from Vlan2 through Vlan15 instead of vlan1 through vlan14.

Or am I missing the point here?

you can change the native vlan on a per port basis.  On this Cisco hardware at least:

switchport trunk native vlan 2

I suspect Cisco have put native vlan as vlan 2 on this particular hardware because of previous interoperability problems.  

Trouble is, if you do away with vlan 1 completely, omslaw will have to reconfigure the entire existing 3com network - particularly as he's trunking between the Cisco & 3com.

The alternative of changing the native vlan is to reconfigure the 3com to untag vlan 1 (just on the trunk to the Cisco), that'll probably do it too.

Still, its an interesting problem.



<!--EDIT|kod3001
Reason for Edit: None given...|1130189771 -->

 

[omslaw]

sorry guys, got drug into a meeting... I'm back...

OK setting native vlan for GI0/17 to 4000 let's see...

 

[gsferrari]

#switchport trunk vlan native nn

will change the vlan number for the native vlan. You can change on both switches. But it will be easier to untag the 3Com native vlan frames...if that is possible (I have no idea).

 

[omslaw]

Nope, that didn't help...trying the spanning-tree thing...

 

[omslaw]

Nah, tried untagging from the 3com...no dice.

Also, like KOD pointed out, my entire internal, production infrastructure is on VLAN1...I *really* need to gain access to VLAN1 from the Cisco.

 

[omslaw]

spanning-tree change didn't help, either.

 

[gsferrari]

Just change the VLAN1 on the cisco device to VLAN20 or something...that should tag all VLAN1 traffic as well...

If this doesnt work then I am stumped

 

[cache]

have you tried the 3com configurator?

 

[omslaw]

No, but I'm not convinced that it's a 3Com issue. Well, I guess it could be attributed to the way 3Com does stuff...

I think it's Cisco's use of wanting to keep VLAN1 a management-only VLAN. By me having...wanting...NEEDING to have production traffic on VLAN1, I think it's giving the Cisco a fit. (that or I need to *really* creative IOS programming!)

 

[cache]

I guess your determined to do things the hard way then..

 

[omslaw]

I didn't say that! Where is this configurator that you speak of? I have always config'd from the CLI.

 

[Sane_man]

I had to go to an interview. I thought you would have this figured out by now!!

I wish I was there in person to look at this, but I will do some research tonight.

It sounds like IBM setup your native VLAN as VLAN 2 to keep you from having issues as stated earlier. I'm starting to get confused, so I will draw this out in Visio and printout your config so I can see this better.

 

[omslaw]

LOL! Hope the interview went well.

Would a webex session help?

 

[cache]

yes.. websex......

 

[omslaw]

Hmmm....what's on Cache's mind?

 

[cache]

common tool for 3com and other switches:
http://www.kiwisyslog.com/cattools2.htm


http://www.redbooks.ibm.com/redpapers/pdfs/redp3869.pdf



maybe you find something to help....