RE: Re: iSCSI: SCTP Switch and Router support

["Thomas Crowe" <thomas_crowe@yahoo.com>]

Switches are aware of protocol from a layer 4 perspective to enhance
performance, not make switching decisions.  The two company's that you
mention (Alteon and Foundry) both make layer 4 switches that are designed to
make switching decisions on TCP sessions, one of those devices would not be
used in the transport of iSCSI packets, they are used instead for the
loadbalancing of webservers and the like.  Foundry also make pure layer 2
switches as well as layer 2/3 routing switches.  AccessLists would be
affected but that alone should not be a driving factor in not supporting
SCTP.

MTU path discovery is NOT a function of TCP, that is done with ICMP.

Just to clarify, I am not supporting / not supporting SCTP I simply wanted
to clarify some of the network issues.

> -----Original Message-----
> From: owner-ips@ece.cmu.edu [mailto:owner-ips@ece.cmu.edu]On Behalf Of
> somesh_gupta@hp.com
> Sent: Thursday, August 24, 2000 1:22 PM
> To: Black_David@emc.com; hufferd@us.ibm.com
> Cc: ips@ece.cmu.edu
> Subject: RE: Re: iSCSI: SCTP Switch and Router support
>
>
> I agree. Look at switches by a lot of vendors (like Alteon,
> Foundry etc.). In general, the trend towards being aware of
> TCP connection flows (keeping actual connection states) is
> increasing with some switches capable of maintaining state
> information for upto a million connections.
>
> In addition to things mentioned by John, it is also going to
> be used (or already being used) for traffic classification
> (VLAN and priority). It is an important component of traffic
> engineering.
>
> (on a comment by Doug, most (all??) TCP implementations today
> avoid fragmentation also (by using path MTU discovery) since
> fragmentation is so expensive for routers or receivers.
>
> Somesh
>
> > -----Original Message-----
> > From: hufferd@us.ibm.com [mailto:hufferd@us.ibm.com]
> > Sent: Thursday, August 24, 2000 9:19 AM
> > To: Black_David@emc.com
> > Cc: ips@ece.cmu.edu
> > Subject: FW: Re: iSCSI: SCTP Switch and Router support
> >
> >
> > David,
> > A lot of what you say is true, however, the word "Most" is
> > the key.  There
> > are a number of Switches, NATs, Proxies, and Load Balancers
> > that actually
> > care about TCP/IP.  I do not believe they will handle the SCTP in a
> > transparent manor.
> >
> > .
> > .
> > .
> > John L. Hufferd
> > Senior Technical Staff Member (STSM)
> > IBM/SSD San Jose Ca
> > (408) 256-0403, Tie: 276-0403
> > Internet address: hufferd@us.ibm.com
> > Notes address: John Hufferd/San Jose/IBM @ IBMUS
> > VM address: hufferd at IBMUSM54
> >
> >
> > Black_David@emc.com on 08/24/2000 08:54:46 AM
> >
> > To:   John Hufferd/San Jose/IBM@IBMUS
> > cc:   ips@ece.cmu.edu
> > Subject:  iSCSI: SCTP Switch and Router support
> >
> >
> >
> > John,
> >
> > > 3. We will need to get the Switch and Router folks to also
> > support SCTP
> > and
> > > to do it in Hardware so that the speed and throughput can
> > be maintained.
> > I
> > > do not see that happening, at least not right away, when we
> > need to get
> > > volumes moving in order to validate the IP storage SAN concept.
> >
> > I don't understand this.  Most switches and routers
> > have no knowledge of whether TCP, UDP, or even IPsec
> > encapsulated (and hence opaque) traffic is flowing
> > through them.  What's special about SCTP -- is this
> > about layer 4 and higher switches/routers?
> >
> > --David
> >
> > ---------------------------------------------------
> > David L. Black, Senior Technologist
> > EMC Corporation, 42 South St., Hopkinton, MA  01748
> > +1 (508) 435-1000 x75140, FAX: +1 (508) 497-6909
> > black_david@emc.com  Cellular: +1 (978) 394-7754
> > ---------------------------------------------------
> >
> >
> >


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