Mailing List Archive: nsp: extreme

vlan trunk between summit 400 and cisco 3750

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ylchang at seawind

Aug 25, 2006, 2:53 AM

Post #1 of 4 (2155 views)
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vlan trunk between summit 400 and cisco 3750

Hi,

I cannot VALN trunk between summi 400 and cisco 3750
by following steps,

on summit 400, add port 1 to "VLAN v100 tagged"
and add port 1 to "VLAN v200 tagged". Where v100
is VLAN ID 100 and v200 is VLAN ID 200.

On Cisco 3750, I cofig port 1 as
switchport
switchport trunk encap dot1q
switchport trunk allowed vlan all
switchport mode trunk

but the PC (access to vlan 100) on cisco 3750 cannot
ping to PC on summit400 with the same VLAN ID.

Does someone can provide a example if I am lucky that
someone has a running case.

thank you in advanced.

--
Yu-lin CHANG

jonathan.ruano at interoute

Aug 25, 2006, 3:13 AM

Post #2 of 4 (2079 views)
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vlan trunk between summit 400 and cisco 3750 [In reply to]

Yu-lin,

I'm still getting acquainted to the Extreme swiches, but I'd check a
couple of things:

a) Make sure ip forwarding is enabled on the summit (not sure if these
switches have/need this.)

enable ipforwarding vlan "v100"

b) VLAN 100 should be created on the cisco (e.g, conf term, vlan 100,
exit, exit)

You may want to see if you can see the Mac addresses of both devices on
the switches.

Jon
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ylchang at seawind

Aug 25, 2006, 11:01 PM

Post #3 of 4 (2079 views)
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vlan trunk between summit 400 and cisco 3750 [In reply to]

Hi Jonathan and all,

Thanks for all your help. The VLAN trunk between Summit400
and Cisco3750 is now working. What I did are,

1. on cisco3750
interface g1/0/1
switchport
switchport trunk encap dot1q
switchport mode trunk
switchport trunk allow vlan 100,200
2. on Summit400
config vlan v100 add port 1 tag
config vlan v200 add port 1 tag
3. go back to cisco3750
interface g1/0/1
shutdown
(wait few seconds)
no shutdown

Then, the VLAN trunking works as expect.
BUT!!! another problem follows!!!

PCs on C3750 can now communicate with PCs on S400
without problem. But other cisco and summit switches
on S400 are now isolated!!!

I read some interface error messages on other cisco
switches (most of them are 2950) said they received
unexpected vlan-trunking information on a
non-vlan-trunking port.

%SPANTREE-7-RECV_1Q_NON_TRUNK: Received 802.1Q BPDU
on non trunk GigabitEthernet0/1 VLAN1.

%SPANTREE-7-BLOCK_PORT_TYPE: Blocking GigabitEthernet0/1
on VLAN0001. Inconsistent port type.

I don't know why S400 sends tunking information to those
"untagged" ports.

Finally, I have no choice to move all switch links from
"untagged" to "tagged" and config those 2950s GE uplinks
to VLAN trunking.

Does anyone has similar experience on this?

thanks and regards,
--
Yu-lin CHANG

---------------------------------------------
Jonathan Ruano wrote:
> Yu-lin,
>
> I'm still getting acquainted to the Extreme swiches, but I'd check a
> couple of things:
>
> a) Make sure ip forwarding is enabled on the summit (not sure if these
> switches have/need this.)
>
> enable ipforwarding vlan "v100"
>
> b) VLAN 100 should be created on the cisco (e.g, conf term, vlan 100,
> exit, exit)
>
> You may want to see if you can see the Mac addresses of both devices on
> the switches.
>
> Jon

swmike at swm

Aug 25, 2006, 11:20 PM

Post #4 of 4 (2069 views)
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vlan trunk between summit 400 and cisco 3750 [In reply to]

On Sat, 26 Aug 2006, Yu-lin CHANG (seawind) wrote:

> I don't know why S400 sends tunking information to those
> "untagged" ports.

It doesn't. It just forwards the spanning tree packets without doing
anything about them. Most likely it's the 3750 that runs PVST or some
other STP on the vlans you're trunking to/from it and this gets forwarded
by the S400 as any other packet, and then the 2900 has some default
protection turned on against this case and complains.

I usually say that Cisco switches are the Macintoshes of the switch world.
They have a lot of things turned on that "just works" in a pure Cisco
environment, but as soon as you start to interconnect them with other
brands, you really have to know everything they do and don't and handle it
by turning off things or changing the defaults.

"no spanning tree vlan 100" and 200 on the 3750 might solve this problem,
or turning off bpdu-guard on the 2900.

--
Mikael Abrahamsson email: swmike at swm.pp.se

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