RE: ISL Trunking vs dot1q

From: Asbjorn Hojmark (Asbjorn@xxxxxxxxxxx)
Date: Fri Mar 02 2001 - 19:52:34 GMT-3


   
> Speaking of vlans, most of Cisco's devices currently support
> 1024 vlans.

>From CatOS 6.1, the Catalyst 6000 series support 4096 VLANs as
per the 802.1Q standard.

> Anyone know of any real world situations where more than 150
> vlans are in place?

I don't know the exact numbers, but I've worked on two installa-
tions that are at least very close to that. Given two subnets
(for load-balancing) in each wiring closet plus two voice VLANs,
it'll add up pretty quickly.

Going from a couple of hundred to 4096 is one big step, however,
and I guess that feature is primarily implemented to be able to
say that they adhere to the standard.

> I have spoken to people with extensive experience in the field
> who claim they have never seen more than a dozen of so vlans in
> the real world.

Maybe they work mainly on small to medium size installations?

-A

--
Heroes: Vint Cerf & Bob Kahn, Leonard Kleinrock, Robert Metcalfe
Links : http://www.hojmark.org/networking/


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