From: Thounda Craig Jr. (hjcgroup@xxxxxxxxxxxxxx)
Date: Tue Dec 26 2000 - 22:58:29 GMT-3
ISL is a Cisco technology ONLY (802.1q is for non-Cisco equipment).
Note: Cisco is looking at removing ISL in favor of 802.1q to be more
compliant w/other vendor products.
Yes, ISL is for ethernet.
----- Original Message -----
From: "Asbjorn Hojmark" <Asbjorn@Hojmark.ORG>
To: <ccielab@groupstudy.com>
Cc: "'Kevin Baumgartner'" <kbaumgar@cisco.com>; "'Earl Aboytes'"
<Earl@dnssystems.com>; "'Padhu (LFG)'" <padhu@steinroe.com>
Sent: Tuesday, December 26, 2000 5:34 PM
Subject: RE: TR Switching
> > I believe you need to use a Cat 3900 with a ISL card to do TR
> > ISL.
>
> Well, it could also be a couple of C5Ks.
>
> > The ISL card is a ethernet trunk to another switch and TR VLANs
> > are encapsulated in it.
>
> In the strictest sense, ISL isn't an *ethernet* trunk. Ethernet
> trunking is defined in 802.1Q and while ISL can *carry* ethernet
> VLANs, ISL framing can hardly be called ethernet, and ISL carry-
> ing token-ring can in no way be called ethernet.
>
> I know Cisco marketing would argue otherwise, but in my mind, ISL
> isn't ethernet any more than, say, ATM LANE.
>
> > The Cat 3920 doesn't have a ISL uplink.
>
> Huh? What about WS-C3900-2ISL?
>
> Did you mean to say, there's no such thing as a 3920-uplink that
> takes token-ring VLANs and bridges to a trunk with ethernet fra-
> ming? (Sort of like the Olicom 8660 which also does 802.1Q).
>
> No, the thing that comes closest is a 5000-series switch with a
> token-ring blade and a route-switch module. (Not really economi-
> cally an attractive alternative).
>
> > And I don't think there exists native TR ISL
>
> I agree. There's ISL carrying ethernet and ISL carrying token-
> ring, but no such thing as native ethernet ISL og native token-
> ring ISL.
>
> > Certainly can stack 3920 switches using a special cable but
> > no mention of TR ISL.
>
> Stacking on the 3920 is ISL (carrying token-ring).
>
> -A
>
>
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