RE: ISCSI: Urgent Flag requirement violates TCP.

["Bernard Aboba" <aboba@internaut.com>]

>More generally, along what sort of possibly lossy, possibly reordering
>paths will iSCSI be trying to squeeze out Gbps+ rates?

In a switched Ethernet environment operating over LAN/MAN/WAN,
we will not see reordering, and only (very) occasional packet loss. 
So the concern would be to prevent a huge decline in transfer
rate in the event of a loss. However, I think that can be
addressed via a combination of RDMA and fast re-transmit. 
In this kind of environment, I would expect that SACK 
would only be of occasional relevance.