From: John Neiberger (neiby@xxxxxxxxxx)
Date: Wed Nov 07 2001 - 12:27:10 GMT-3
I'm not sure but you may be encountering a feature that Cisco says is fixed
yet it keep popping back up.
With ISL, all frames are tagged including VLAN1 so if you configure your
router trunk with subinterfaces and place VLAN1 on one of those
subinterfaces with ISL encapsulation all will work just fine.
802.1q does not tag VLAN1 (or whatever you designate as your 'native' vlan).
If you place VLAN1 on a subinterface with 802.1q encapsulation the router
won't recognize packets from this vlan.
The trick is to configure your major FastEthernet interface with the IP
address of VLAN1 and put the remainder of your vlans on subinterfaces with
dot1q encapsulation.
Supposedly this has been fixed but I tried an image they said should work
and it still didn't.
It sounds like you might be running up against something like this if I'm
reading your symptoms correctly.
Good luck,
John
On Tue, 6 Nov 2001 22:44:46 -0800 (PST), Erick B. wrote:
| Hello there,
|
| I've been playing around with some VLAN stuff lately
| and have seen some odd behavior with trunking and I
| can't find a answer so thought I'd see if anyone here
| knew, because it is bugging me.
|
| Real basic setup.
|
| Cisco router with FE connecting to a switch. VLANs 1,
| 2, and 3. Workstation on switch in VLAN 2 and VLAN 3.
|
| Dot1Q trunk with all VLANs defined. Sub-interfaces on
| router for dot1q. Ping from PC in VLAN2 to VLAN3 and
| don't get further then router interface for that VLAN.
| Change to ISL encaps and everything works fine. Change
| back to Dot1Q and things continue to work. Save
| configs and reload switch and routers and things
| continue to work.
|
| I also had a similar thing when I didn't configure a
| VLAN1 sub-interface on the router (just 2 and 3). Once
| I added VLAN1 thing started working. Took VLAN1 away
| for kicks and things still worked. Weird.
|
| Any one have any thoughts???
|
| Thanks, Erick
|
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