RE: Lacp, dot1q, SPT, native vlan and Management Vlan concepts

I apologize for not seeing that the second device was a Nortel switch.

-----Original Message-----
From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of Anantha Subramanian Natarajan
Sent: Wednesday, November 04, 2009 3:08 PM
To: Rob Clav
Cc: CCIE Groupstudy
Subject: Re: Lacp, dot1q, SPT, native vlan and Management Vlan concepts for troubleshooting.

Hi Rob,

  Trying to understand your question ,

Are you trying to form Layer2 etherchannel(LACP) using dot1q encapsulation
between cisco 2960 switch and a nortel switch ..Is that right ?

If so,whats the native vlan on the trunk configured on nortel switch side
?...I am understanding that,you don't have issue with etherchannel and only
dot1q encapsulation..can you please clarify,how you verified LACP seems
working fine ....

Thanks

Regards
Anantha Subramanian Natarajan

On Wed, Nov 4, 2009 at 4:15 AM, Rob Clav <robclav_at_gmail.com> wrote:

> Hi folks,
>
>
>
> I was pretty sure about this concepts in the past, but after check them
> configuring a C2960 with a nortel switch I have several doubts.
>
>
>
> Can you say if i'm wrong with any statement?
>
>
>
> LACP.- standard dynamic protocol used to negociate links aggregation. In
> order to activate it, you need to add a command, to the interfaces
> joinning
> to a virtual interface(layer 2 or not) called port-channel. You can
> activate
> lacp to be the expected(active), to lisen for a lacp negotiation from the
> other site or to say the channel-group is on without negociation. At
> port-channel virtual interface you need to configure the same that you
> configure at physical int.
>
>
>
> DOT1Q and native vlan.- standard dynamic protocol in order to allow more
> than one vlan crossing the link. One of these vlans is called native
> because
> is the one used to carry the control protocols like cdp,spt(one instance)
> and so one. This one is send it untagged by default. The rest of the vlans
> are send tagged. You can tag native vlan in some devices like 3750 but at
> 2960 you couldn t with the command "vlan dot1q native tag". The kind of
> encapsulation should be choosed in some models supporting isl. Then you can
> say if the trunk will be desirable, will expect the action of the other
> site
> of the link, if will be on or the negotiation will be deactivated.
>
>
>
> Management VLAN.- Is used at layer 2 devices to configure an IP Address in
> order to manage the switch. This one could be the native vlan or not. By
> default at layer 2 devices, this one must be the native as well.
>
>
>
> SPT.- Well-known anti layer 2 loop protocol. There are several kinds like
> CST, PVST, PVST+(cisco) ,RST, MST, RPVST+(cisco). The first one support
> only
> one instance for whole spt domain, and the rest support a instance and then
> a root for each vlan.
>
> As compatible SPT I use, CST, or mst. I read at some forums that 802.1q
> doesn't support PVST+ except if you use only Cisco switches.
>
>
>
>
>
> Summary,
>
> I have a Cisco 2960 trying to establish an etherchannel with a 801.q trunk
> configuration. But it doesn't works. Obviously, I tried to break the
> problem
> in some smaller ones. Well the main problem is that I need to change the
> management vlan to other(Vlan 63) because the subnetting. And then I tried
> to make the management(Vlan 63) as a native also. I tried too, using one
> vlan(63) for management and other one(Vlan 1) as a native. But no positive
> results.
>
>
>
> The picture of the config is that I have vlan 63 as management and I assume
> vlan 1 is the native, because you couldn t remove it.
>
>
>
> 1.-I tried to check connectivity between one link without trunk or
> etherchannel config, basically acting as an access port. It works
>
> 2.-I tried to configure a trunk between them, and didn't work. In fact, I
> tried several configuration, negotiating the trunk and forcing it, but
> nothing.
>
> 3.-LACP seems to work fine, without 802.1q.
>
>
>
> Well at the end of this email I realize that I have a problem with the
> trunk+native vlan and SPT, but I don't know why. It's a lab environment so
> I'm sure there's no third cable between them to loop it. Any idea?
>
> Thanks in advance,
>
> Robclav
>
>
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Received on Wed Nov 04 2009 - 15:14:20 ART