>From: "Howard C. Berkowitz" <[EMAIL PROTECTED]>
>Reply-To: "Howard C. Berkowitz" <[EMAIL PROTECTED]>
>To: [EMAIL PROTECTED]
>Subject: Re: BPX going out of style?
>Date: Tue, 13 Feb 2001 14:26:13 -0500
>
> >John,
> >I have heard many tales of how ATM will explode soon, will be partenered
> >perfectly with DSL, and everyone will implement it, but I just haven't
>seen
> >it.
>
>In many respects, MPLS is ATM without cells. In the carrier space,
>some of the concerns that ATM was meant to solve are being overtaken
>by events. Having small cells to improve latency and jitter makes
>lots of sense at T1 and even T3 rates, and some even at OC-3. At
>OC-192, I can send full frames faster than I could send cells.
Cool
> >I like the idea of improving technologies your engineering and support
> >staff are familiar with (Not counting new technology with old names like
> >IPv6). I hope this is able to work out, and isn't too far down the road.
> >Is there any talk of using smaller tags in IP to create big pipes similar
>to
> >ATM's VCI's so that you could lower the ip address & mask-lookup
>processor
> >overhead on backbone IP routers?
>
>Not wildly different from what MPLS does, which would most commonly
>use a 20-bit label inside a 32-bit field. But speaking as someone
>actively involved in backbone router design, the 32 bit lookup isn't
>a huge performance issue. Many other things, such as filtering,
>accounting, and traffic shaping, are where you take the hits.
>
>Other considerations are a need to look up the source address, if for
>no other reason as part of denial of service protection (e.g.,
>reverse path verification).
Shouldn't these types of functions (filtering,accounting, traffic shaping,
and source routing)be implemented at the outside edge if the network? Like
in the Cisco model the Distribution layer could handle these functions on
the outside interface and the inside interface could run this tag-to-ip
destination lookup and send to the correct pipe if deemed necessary? Then
again this lookup would probobaly be counter productive in the interest of
reducing CPU overhead.
> >I think this would be a neat idea. Even
> >though the CAM table is fast the router must still read the entire
>address
> >and mask. Small pipe identifiers could be inserted into the ip header and
> >extracted at the gateways and lookup would be lowered. Like xtags on
>VLANS.
> >
> >>>>Brian
> >
> >
> >>From: [EMAIL PROTECTED] (John Nemeth)
> >>To: "Brian Lodwick" <[EMAIL PROTECTED]>, [EMAIL PROTECTED]
> >>Subject: Re: BPX going out of style?
> >>Date: Sat, 10 Feb 2001 05:01:31 -0800
> >>
> >> From what I see, there seems to be a lot of emphasis on GigE and
> >>the very rapidly upcoming 10GigE combined with QOS now adays. ATM
> >>really doesn't seem to work that well with data (TCP/IP) and has a very
> >>high overhead. Ethernet is getting fast enough that when combined with
> >>QOS it can easily handle voice and video as well as data. Also,
> >>ethernet is cheap, cheap, cheap; even GigE when you compare it with
> >>ATM, and just about everybody knows how to handle ethernet, but ATM is
> >>something that relatively few people know really well.
> >
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