Subject: RE: FCIP: Comment 120

From: [email-masked]
Date: Thu, 9 May 2002 16:39:09 -0400

> > Besides, I don't see anything in the current document that prohibits
multiple
> > FC/FCIP Entity Pairs from sharing the same IP/TCP address/port - and I
believe
> > that is the right architectural approach.
> 
> In the Orange County meeting, the FCIP contributors were told that we
> had to stop relying on knowing the exact IP Address and Port to decide
> the end points of the FCIP Links. We were NOT told that we had to
> allow multiple FC/FCIP Entity Pairs to share a single IP Address/Port.
> In fact, I believe we were told that we could proceed using such
> an assumption.

While Ralph doth protest a bit much, I believe he has the better part
of this discussion.  It is completely reasonable to identify an IP
service instance as "that which responds when contacting TCP port X
at IP address a.b.c.d" - for example, there's only one http server
behind port 80, but there might be a different one behind port 8080.

If there's a NAT involved, the discussion gets a bit subtle, but
the principle remains - one opens a TCP connection to port X at
IP address a.b.c.d, and expects to talk directly to a specific instance
of an IP-based service.  I don't see any need to change FCIP to
allow multiple FC/FCIP Entity Pairs to share a single IP Address/Port;
the fact that multiple TCP connections to the same FC/FCIP Entity
Pair can share that TCP Port seems sufficient.  Having seen no other
participants in this discussion, I also believe that the rough
consensus of the WG is not to change FCIP in this fashion.

Thanks,
--David
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David L. Black, Senior Technologist
EMC Corporation, 42 South St., Hopkinton, MA  01748
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[email-masked]         Cell: +1 (978) 394-7754
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From: "Mallikarjun C." <[email-masked]>
Date: Thu, 9 May 2002 16:32:02 -0700

David,

From the text that Murali posted on this thread - 

" The FC-BB-2_IP Reference Model supports one logical IP Interface and
allows sharing a 4-byte IPv4 or 16-byte IPv6 address in the following ways:

a)A single IP address per FC-BB-2_IP device
  - A single IP address shared by all FC/FCIP Entity pairs"

It's a simple extension to assume that the same well-known TCP port
*could* be used for all Pairs, which results in multiple Pairs at the same *address*
necessitating a *name* of some sort to identify the intended FSF recipient.

>Having seen no other
> participants in this discussion,

Please see Murali's message.

>I also believe that the rough

I am *not* advocating a change.  I am simply concerned that the FCIP 
text is neither ruling out certain possibilities explicitly, nor defining the 
architectural hooks to cater to all possibilities.  I'd be perfectly okay with
a statement that states that each IP-TCP Address-Port belongs to exactly
one Pair (though the text then should ideally say why). 

Thanks.
--
Mallikarjun

Mallikarjun Chadalapaka
Networked Storage Architecture
Network Storage Solutions Organization
Hewlett-Packard MS 5668 
Roseville CA 95747
[email-masked]