RE: [nsp] ISL/dot1Q trunks on 26xx

From: Scott Morris (
Date: Mon Dec 11 2000 - 14:19:41 EST

The 300 IDB limit thing hasn't been fixed for quite a while. It's really
memory and IOS-level dependent right now. If you max out the memory on the
2600, you should easily get beyond that in interfaces. I've got about 500
running on a 3620 between VLANs and Frame sub-interfaces on one clients'
router. There's a "show idb" hidden command, but unfortunately, I don't
know any way of finding out the maximum for your configuration.


-----Original Message-----
From: Andrew Smith []
Sent: Monday, December 11, 2000 2:07 PM
To: Charles Sprickman
Subject: Re: [nsp] ISL/dot1Q trunks on 26xx

On 11-Dec-2000, Charles Sprickman wrote:
> Hi,
> Does anyone know of the max number of subinterfaces one can put on an FE
> port of a 2600 series router? I'm looking at about 200-400 with a fairly
> light overall traffic load (less than 6 Mb/s aggregate).

I believe that you are going to hit the max IDB limit on the 2600
at 300 total interfaces (including subinterfaces).

> Also, what's the general performance impact of doing trunking off of a
> router?

I haven't seen any significant impact in router performance by simply
using dot1q or ISL subif's. I don't know much about the physical FE
on the 2600's and how well it will operate as a "router on a stick"
as in, how well it performs in full-duplex capacity.

> Thanks,
> Charles

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