Mailing List Archive

On Thu, 1 Aug 2002 19:08:18 -0700 (PDT) Benjie Ko <gerwalk1@yahoo.com> wrote:
> Is it possible to put a transparent ethernet bridge
> (bandwidth manager) between two cisco switches doing ISL
> trunking?
>
> Will the ISL link still go up?
> According to our supplier as long as the ethernet
> frames are standard w/ standard vlan tagging, it should work, but they
> are not familiar with ISL encapsulation so they cant give me a conclusive
> answer.

ISL isn't "standard VLAN tagging" so this almost certainly won't work.
802.1q ("dot1q") is standard however, so if you can use that for trunking
instead it should work.

--
Ryan O'Connell - CCIE #8174
<ryan@complicity.co.uk> - http://www.complicity.co.uk

I'm not losing my mind, no I'm not changing my lines,
I'm just learning new things with the passage of time

But in this case, the BW manager needs to "understand" tagged frames.
I've one in production and it doens't support tagged frames, so doens't
handle or apply configured policy.

Luciano

-----Mensaje original-----
De: cisco-nsp-admin@puck.nether.net
[mailto:cisco-nsp-admin@puck.nether.net]En nombre de Ryan O'Connell
Enviado el: Viernes, 02 de Agosto de 2002 05:44 a.m.
Para: Benjie Ko; cisco-nsp@puck.nether.net
Asunto: Re: [nsp] bandwidth manager


On Thu, 1 Aug 2002 19:08:18 -0700 (PDT) Benjie Ko <gerwalk1@yahoo.com>
wrote:
> Is it possible to put a transparent ethernet bridge
> (bandwidth manager) between two cisco switches doing ISL
> trunking?
>
> Will the ISL link still go up?
> According to our supplier as long as the ethernet
> frames are standard w/ standard vlan tagging, it should work, but they
> are not familiar with ISL encapsulation so they cant give me a conclusive
> answer.

ISL isn't "standard VLAN tagging" so this almost certainly won't work.
802.1q ("dot1q") is standard however, so if you can use that for trunking
instead it should work.

--
Ryan O'Connell - CCIE #8174
<ryan@complicity.co.uk> - http://www.complicity.co.uk

I'm not losing my mind, no I'm not changing my lines,
I'm just learning new things with the passage of time

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> On Thu, 1 Aug 2002 19:08:18 -0700 (PDT) Benjie Ko <gerwalk1@yahoo.com>
wrote:
> > Is it possible to put a transparent ethernet bridge
> > (bandwidth manager) between two cisco switches doing ISL
> > trunking?

I think your bridge will be confused because the Ethernet Addresses won't be
at the front of the frame. The ISL format is like this:

ISL Header | Original Frame | FCS
http://www.cisco.com/warp/public/473/741_4.html

ISL may work if the bandwidth manager only allows 'n' frames in each
direction. I'd imagine the box you want is more sophisticated; you can
probably configure bandwidth based on L3 or L4 information. Once ISL has
shifted your frames, the bandwidth manager won't find the L2 or L3
information where it expects.

802.1q would work in this situation, but you might see giant sized frames
come through the bandwidth manager. I have used 802.1q over some 10Mbps
radio links where we HAD to allow 2 VLANs. As long as your bandwidth manager
won't disable ports due to errors, you'll be all set.


Hope this helps!
Ton Wasson

Hi!

I attended a Packeteer course last month, and it supports ISL
trunking. The productline is from PacketShaper 1500 to 8500. These devices
have two 10/100 Ethernet port by default, and LAN Extension Module, so you
can connect 4 LANs (except the smallest device, PS1500).

Attila

On Fri, 2 Aug 2002, Tony Wasson wrote:

> > On Thu, 1 Aug 2002 19:08:18 -0700 (PDT) Benjie Ko <gerwalk1@yahoo.com>
> wrote:
> > > Is it possible to put a transparent ethernet bridge
> > > (bandwidth manager) between two cisco switches doing ISL
> > > trunking?
>
> I think your bridge will be confused because the Ethernet Addresses won't be
> at the front of the frame. The ISL format is like this:
>
> ISL Header | Original Frame | FCS
> http://www.cisco.com/warp/public/473/741_4.html
>
> ISL may work if the bandwidth manager only allows 'n' frames in each
> direction. I'd imagine the box you want is more sophisticated; you can
> probably configure bandwidth based on L3 or L4 information. Once ISL has
> shifted your frames, the bandwidth manager won't find the L2 or L3
> information where it expects.
>
> 802.1q would work in this situation, but you might see giant sized frames
> come through the bandwidth manager. I have used 802.1q over some 10Mbps
> radio links where we HAD to allow 2 VLANs. As long as your bandwidth manager
> won't disable ports due to errors, you'll be all set.
>
>
> Hope this helps!
> Ton Wasson
>
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