The IP Over NBMA (ION) Archive

["Eric W. Gray" <gray@cabletron.com>]

Yakov,

You wrote (in part):
> 
> Eric,
> 
...
> 
> > Label-swapping is also done - at the network layer - by routers as
> > they forward packets.
> 
> Would you please explain what is exactly "label-swapped" in an IP
> header  when a router forwards an IP packet ?
>

Could be I'm wrong, but I was under the impression that a router swaps
the 12-byte "label" preceding the L3 header based on a Network layer
decision.  You're not proposing that the L3 header be partially replaced
during the tag-swapping are you?

> 
> >         Speaking of tag-switching at the network layer, how is that
> > different than what Isilon switches do?  As I understand it, they do
> > switching at the IP (Network, right?) layer and I'd be very surprised
> > if they don't use VPI/VCI-like tags in doing it.
> 
> There are several differences between tag switching and Ipsilon IP
> switching. For one thing, tag switching supports much broader
> spectrum of forwarding granularities than Ipsilon IP switching.
> Another difference is that with Ipsilon IP switching creation of
> "VPI/VCI-like tags" is traffic driven, while with tag switching tags
> are created as a "by-product" of routing. There are other differences
> as well, but to keep this short I wouldn't go into more details.
>

So, you would relinquish any claims you might have to use of tags resulting
from traffic-driven decisions within the network?  This could be important
to MPOA, for instance.

> 
> >         Anyways, I appreciate the timely information provided in this
> > internet draft.
> 
> If you'd like to get more info on tag switching I would suggest
> to join tagswitching mailing list.
>

Love to.  I must have missed the advert for that list - is it part of
an IETF area?  With whom do I subscribe?

> 
> Yakov.

--
Eric Gray
mailto:eric.gray@nh.ultranet.com / gray@ctron.com
http://www.nh.ultranet.com/~egret