RE: iFCP CRC

[Wayland Jeong <wayland@troikanetworks.com>]

What iFCP does is it separates the name space between connected SAN devices
by mapping FC MAC addresses (D_ID's and S_ID's) to IP addresses through the
use of an IP based name server (iSNS). In order to do this, it must inspect
FC frames entering the gateway from an N_PORT or E_PORT and map the locally
assigned D_ID with the IP address of the destination gateway and the actual
D_ID of the targeted device. Thus, the gateway must modify the FC frame by
inserting the actual destination FC MAC into the encapsulated FC frame. The
destination IP address is the IP address of the gateway behind which is the
actual FC target. The destination gateway strips the network headers and
substitutes its local label for the S_ID in the bridged FC frame. The
salient difference here which, in my mind makes the two proposals (iFCP and
FCIP) difficult to reconcile, is the fact that iFCP does not require FC-BB.
The devices on each side of the gateway are completely isolated from one
another in the FC sense.

I think a lot of the confusion on this reflector is coming from the fact
that "implementation" issues related to how to do this are not included in
the draft proposal. One can imagine a bunch of inventive things that could
be done to implement a device which acted like an E_PORT but performed these
iFCP gateway functions. I believe, to make this draft more clear, it would
be useful to go into more detail on how the gateway behaves in the FC
network.

-----Original Message-----
From: Matt Wakeley [mailto:matt_wakeley@agilent.com]
Sent: Thursday, December 14, 2000 4:04 PM
To: IPS Reflector
Subject: Re: iFCP CRC


Joshua Tseng wrote:
> 
> Wayland,
> 
> One important detail which was accidentally omitted from the
> iFCP document is that the FC CRC (along with EoF and SoF) is
> stripped off and not encapsulated in the iFCP PDU.  As you guessed,
> the reason this was done is because iFCP changes the S_ID and
> D_ID in the original FC frame.

Why are the S_ID/D_IDs changed?

-Matt