[stgt] iSER over iWARP

[Or Gerlitz]

On 04/10/2013 02:20, Sushma R wrote:
> I experimented around a bit and here are my observations:
>
> 1. tgtd (Version 1.0.24) which comes with CentOS 6.4 distribution
> doesn't have iSER support. Configured targets as iscsi/tcp. Initiator
> is able to discover the target and login successfully.
> 2. Compiled latest code from git tree (Version 1.0.39) in iSCSI mode
> and configured targets as iscsi/tcp. Initiator is still able to
> discover targets and login successfully.
> 3. Compiled code from git tree (Version 1.0.39) for iSER support and
> configured targets as iscsi/tcp. Initiator fails to discover targets.
> Same is the case when the targets are configured as iser.

Oh, I think I got it.. when you enable iser we open an RDMA listerner on 
the RDMA equivalent of the iSCSI TCP port (say 3260),
but the iSCSI TCP part of TGT does this too. You might end up with a 
mess, I guess.

With IB and RoCE the problem doesn't exist, only with iWARP, since it 
uses TCP under the RDMA cover. its called
the "port space" problem, a solution to solve that was recently 
submitted upstream but has some way to go before
merged and available to use.


>
> 1542.231217 10.196.86.16 -> 10.196.86.101 iSCSI Login Command
> 1542.231271 10.196.86.101 -> 10.196.86.16 TCP iscsi-target > 53665 [ACK] Seq=1 Ack=49 Win=262096 Len=0 TSV=1890672 TSER=2186863
> 1542.231287 10.196.86.101 -> 10.196.86.16 TCP iscsi-target > 53665 [ACK] Seq=1 Ack=293 Win=261848 Len=0 TSV=1890672 TSER=2186863
> 1542.231295 10.196.86.101 -> 10.196.86.16 TCP iscsi-target > 53665 [RST, ACK] Seq=1 Ack=293 Win=0 Len=0
> 1543.231575 10.196.86.16 -> 10.196.86.101 TCP 53666 > iscsi-target [SYN] Seq=0 Win=14600 Len=0 MSS=1460 TSV=2187863 TSER=0 WS=7
> 1543.231670 10.196.86.101 -> 10.196.86.16 TCP iscsi-target > 53666 [SYN, ACK] Seq=0 Ack=1 Win=65535 Len=0 MSS=1460 WS=3 TSV=1891339 TSER=2187863
> 1543.231688 10.196.86.16 -> 10.196.86.101 TCP 53666 > iscsi-target [ACK] Seq=1 Ack=1 Win=14720 Len=0 TSV=2187864 TSER=1891339
> 1543.231753 10.196.86.16 -> 10.196.86.101 TCP [TCP segment of a reassembled PDU]

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