[openib-general] RE: [iSER]question about iSER code

[Dan Bar Dov]

> -----Original Message-----
> From: xg wang [mailto:xgw200172 at hotmail.com] 
> Sent: Wednesday, August 24, 2005 6:17 AM
> To: openib-general at openib.org
> Cc: Dan Bar Dov; ianjiang91 at hotmail.com
> Subject: [iSER]question about iSER code
> 
> Hi, all!
> 
>     I read the draft-ieft-ips-iser-04 and the iSER source 
> code. In the draft, it wrote "During connection setup, the 
> iSCSI Layer at the initiator is responsible for establishing 
> a connection with the target" and "If the outcome of the 
> iSCSI negotiation is to enable iSER-assisted mode, then on 
> the initiator side, prior to sending the Login Request with 
> the T (Transit) bit set to 1 and the NSG (Next Stage) field 
> set to FullFeaturePhase, the iSCSI Layer MUST request the 
> iSER Layer to allocate the connection resources necessary to 
> support iWARP by invoking the Allocate_Connection_Resources 
> Operational Primitive"
> 
>    So I think that the iSCSI connection is different from the 
> iSER conection since it 'allocate the connection resources'. 
> Does it mean iSER layer will estabilsh another 
> iSER-connection. I am not sure. If it is, then the process is 
> like this:
>   
> 1 iSCSI layer establish connection
> 2 negotiated RDMAExtensions  Yes
> 3 iSRR layer establish connecton---band iSER connection to 
> iSCSI connection
> 4 Notice_Key_Values
> 5 Allocate_Connection_Resources
> 6 send login request user function iser_initiator_send_control
> 
>    Since in the iser code, login request is in function 
> iser_initiator_send_control, and the function used 'struct 
> iser_conn_t p_iser_conn'. I conclude iSER establish an new 
> connecton because the iSCSI connection could not use 
> iser_initiator_send_control if the RDMAExtentsions negotiated 
> as 'No'. 
>      Am I right? 

The ISER spec is iWARP oriented. Please read also the Huffered spec regarding 
ISER over IB. There is work in progress regarding ISER spec modification so it 
becomes transport neutral. The ISER implementation at openIB starts the connection
Already in ISER mode, so the flow you list above is not followed.

>   
>     By the way, there is 'iser_post_send_control', whereas no 
> 'iser_post_receive_control'. How to send the unsolited data 
> from the initiator to target?

These are two questions. Unsolicited data is sent using send-control. 
There is not such thing as receive control - there's control-notify.

Dan
> 
>   Thanks!!
> 
> Computer Architecture Laboratory
> Institute of Computing Technology
> Chinese Academy of Sciences
> Beijing,P.R.China
> Zip code: 100080
> Tel: +86-10-62565533-9314(office)
> 
> xigui wang
> xgw200172 at hotmail.com
> 2005-08-24
> 
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