RE: FCIP/iFCP : Guarantee In-Order delivery for FC N/NL_ports

[Wayland Jeong <wayland@troikanetworks.com>]

> Beyond this, FCIP may have framing issues (identification and placement
> of inbound data in the presence of drops) that are similar to iSCSI
> depending
> on how the FCIP nodes are implemented.
> 
The issue wrt. to framing in an FCIP device is a bit puzzling to me. Framing

for an iSCSI HBA for implementing zero-copy DMA semantics I can understand.
The notification of delivery and the delivery of data is de-coupled, so
order is
preserved in this case.

But, aggressively forwarding through drops in an FCIP bridge is not only
dangerous, it violates TCP layering. Forwarding around dropped PDU's
will introduce all sorts of ordering issues. It seems like an FCIP device 
would want to take the conservative approach and allow TCP to recover
and deliver the PDU's in the order that they were sent. Hence, I don't see
a need to specify a framing method for an FCIP-type device.

> --David
>
-Wayland