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RE: iFCP vs FCIP
At 12:35 PM 11/28/00, Murali Rajagopal wrote:
With my TC hat off:
Charles observation that FCIP's goal to maintain transparency within
the
switching FC Fabric is correct as far data transport is concerned.
However,
there is a clearly defined architecture defined in FC-SW-2 standards
that
allow a device such as FCIP to connect to a border switch. In other
words,
from a routing standpoint the FC fabric is certainly aware of a
hierarchial
network and is supported jointly by the FSPF routing protocol and
the
FSPF-backbone routing protocols. This OSPF-based hierarchial model
provides
a lot of flexibility to the nature of the FC backbone networks.
TCP/IP
happens to be one of the many possabilities. (Other possabilities include
FC
directly over ATM and SONET as defined in the ANSI T11 FC-BB
standards)
Isn't FC-SW-2 still fresh ink specification work by T11? I would think
that a maturity test should equally apply to all the technologies in
IP-land and FC-land that are being considered by this WG (the latest
victim being SCTP in IP-land).
The second plus of
this model is that it allows any type of traffic and
allows for a very simple almost stateless (from FC point-of-view)
behavior.
This directly translates to scalability. The comment made by someone in
this
thread about FCIP being limited is inaccurate- it is in fact the
opposite.
The difference between a future-proof solution and a solution awaiting
for a problem lies exactly in that "any type of traffic". Clues
sought. IMO, iFCP does not seem to preclude ULP-agnostic evolutions
either.
my 0.02
-franco
Finally, Joshua's
comment on the small number of switches in a FC SAN is an
observation from the past and this is rapidly changing as evidenced by
the
growing size of SANs in Data Centers.
-Murali Rajagopal
LightSand Communications
-----Original Message-----
From: owner-ips@ece.cmu.edu
[mailto:owner-ips@ece.cmu.edu]On
Behalf Of
Charles Monia
Sent: Tuesday, November 28, 2000 7:19 PM
To: Ips (E-mail)
Cc: David Robinson (E-mail)
Subject: RE: iFCP vs FCIP
Hi Folks:
The issue is that the design goals and underlying network models
are
fundamentally different. Essentially, FCIP's goal is to provide a
transparent conduit between Fibre Channel fabrics while iFCP's goal is
ULP
transparency between N_PORTs.
As a result, in iFCP, the fabric-wide services provided by FC
fabric
elements (and often implemented with proprietary protocols) are replaced
by
standard, IP-based equivalents. For that reason, an iFCP gateway does
not
need to recognize or provide facilities for servicing inter-switch
FC
protocols, such as those for zoning, naming and routing.
Charles
> -----Original Message-----
> From: Joshua Tseng
[mailto:jtseng@NishanSystems.com]
> Sent: Tuesday, November 28, 2000 4:08 PM
> To: David Robinson; Ips (E-mail)
> Subject: RE: iFCP vs FCIP
>
>
> Hi David,
>
> >
> > I am no FCP expert so please correct me if I am wrong. In a
pure
> > FCP world, there is end-to-end traffic and there is traffic
that is
> > destined to go between AS's. The primary difference is that
there
> > is an explicit route to the border gateways in the latter
> > case. In both
> > the proposals, within the FCP realm the addresses are FCP
> based until
> > they hit an edge node. In iFCP the destination is
> converted to an IP
> > address that represents the end node address (which may
actually be
> > a gateway back into FCP on the other side), in FCIP the request
is
> > routed to the other AS's FC border gateway and this request
is
> > encapsulated
> > in a TCP request. Given that we are moving between AS's
(I
> > believe that
> > is an assumption in FCIP) can we not use iFCP and instead
of
> > specifying
> > the IP address of the end node, specify the IP address of
the
> > other AS's
> > border gateway since FCP should already be doing some
encapsulation
> > to route between AS's?
> >
> > -David
>
> Up until recently with the creation of the DMP routing protocol,
the
> concept of AS's (Autonomous Systems, right?) was foreign to
Fibre
> Channel networking. Most Fibre Channel networks are comprised
of just
> a handful of switches--the largest FC network I have ever heard
of
> being deployed is a 15 switch fabric. Perhaps somewhere there
are
> some fabrics which are bigger, but probably not by much.
> (Architecturally, a single Fibre Channel fabric has a maximum
capacity
> of 239 switches)
>
> FCIP does not do anything to improve the scalability limits of
> the Fibre Channel fabric. All it does is allow extension of
the
> FC fabric over distances using an IP network. The FCIP gateway
is
> completely invisible and non-intrusive to the Fibre Channel
switches
> and does not change or improve the scalability or
interoperability
> limits of FC fabrics.
>
> On the other hand, an iFCP gateway actively participates in
> switching and routing traffic between FC fabrics and FC devices,
by
> mapping FC addresses to IP addresses and routing them using
standard
> IP routing protocols. Using iFCP, a storage network has the
same
> scalability limits as any other IP network (e.g., IPv4 address
space,
> etc...).
>
> Josh
>
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Last updated: Tue Sep 04 01:06:15 2001
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