RE: fcovertcpip - N_Port support.

["Venkat Rangan" <venkat@rhapsodynetworks.com>]

Josh,

On your point below:

> However, the biggest difference between iFCP and FCIP is
> in the addressing and routing mechanisms.  iFCP maps FC
> addresses to IP addresses, which allows IP switches and
> IP routing protocols to route the encapsulated frames to the
> destination FCP Portal over the IP network.  FCIP on the
> other hand relies on the FC switch and FSPF routing protocol
> to route traffic to the final destination, with the role of
> the IP network only to connect tunnel endpoints within the
> FC network.  This is the difference which I am having a hard
> time reconciling.

I think an implementation per fcovertcpip-section 6.2, also requires the
mapping of S_ID and D_ID of FC frames at the N_Port entry into routable IP
addresses. After this mapping, the FC Frame Encapsulation (section 5.2 of
the draft) takes place and these encapsulated frames can be sent out on the
link-layer interface of IP address (corresponding to S_ID) directly, without
involvement of FSPF or E_Ports/ISLs. The component that does this is very
much identical to your iFCP Portal.

There could be other devices whose S_ID and D_ID do not get mapped to IP
addresses, and they are routed by FSPF-established E_Port/ISLs. So, both
routing planes can coexist. If there is no FC plane routed traffic (i.e.,
all name server objects have an IP address mapped to it), it degenerates
into an iFCP switch/gateway, as specified in your draft.

When we look at the Name Server object in FC-GS-3, it already has provisions
to map FC WWN to an IP Address. An implementation can recognize the presence
of an IP Address in this object to decide whether they are sent out on the
IP routing plane or the FC routing plane. The name server itself is a
standard function of all FC-SW-2 switches.

Regards,

Venkat Rangan
Rhapsody Networks Inc.
http://www.rhapsodynetworks.com

-----Original Message-----
From: Joshua Tseng [mailto:jtseng@NishanSystems.com]
Sent: Thursday, December 14, 2000 3:57 PM
To: Venkat Rangan; IP Storage Working Group
Subject: RE: fcovertcpip - N_Port support.


Venkat,

I believe you have a good starting point.  I will offer a
second area of consolidation--that iFCP and FCIP can adopt
a common encapsulation and framing method.  This shouldn't
be too hard--a common encapsulation over TCP that can
support both FCIP and iFCP should be easy to work out.

However, the biggest difference between iFCP and FCIP is
in the addressing and routing mechanisms.  iFCP maps FC
addresses to IP addresses, which allows IP switches and
IP routing protocols to route the encapsulated frames to the
destination FCP Portal over the IP network.  FCIP on the
other hand relies on the FC switch and FSPF routing protocol
to route traffic to the final destination, with the role of
the IP network only to connect tunnel endpoints within the
FC network.  This is the difference which I am having a hard
time reconciling.

Maybe it might be possible to create a common framework,
(rather than a common protocol), under which both of these
separate and unrelated mechanisms can be specified.  The
framework would allow for address translation of FC addresses
into IP addresses & N_PORT ID's, as well as for tunneling of
the frames unchanged over the IP network.

How does this suit everyone???

Josh

>
> In looking at the latest draft-ietf-ips-fcovertcpip-01.txt
> document, it
> looks like Section 6.2 (below) could cover the ability to provide
> connectivity between N_Ports (the area that iFCP covers in
> great detail).
> May be it needs some additional work to diagram and explain
> how this is
> possible, but if that is the case, what additional
> capabilities does iFCP
> proposal provide? Would this not be a natual way to integrate the two?
>
> From draft-ietf-ips-fcovertcpip-01.txt:
> >   6.2 FC Device
> >
> >      The protocol encapsulation and mapping of the FC frame
> described
> >      in earlier sections applies equally to any pair of FC devices
> >      (e.g. switch-to-switch or host-to-storage subsystem) wishing to
> >      tunnel FC frames across an IP-based network.  Any FC routing
> >      protocol exchanges may still occur transparently to the FCIP
> >      devices.  It should be noted that Fibre Channel Primitive
> >      Sequences and Primitives are not exchanged between
> FCIP devices.
>
> Regards,
>
> Venkat Rangan
> Rhapsody Networks Inc.
> http://www.rhapsodynetworks.com
>