RE: iFCP vs FCIP

["Murali Rajagopal" <muralir@lightsand.com>]

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)

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.

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
>