Re: iSCSI and jumbo frames

[mlelstv%serpens.de@localhost (Michael van Elst)]

joel.bertrand%systella.fr@localhost (=?UTF-8?Q?BERTRAND_Jo=c3=abl?=) writes:

>	Of course, I have reconfigured all interfaces, and wm0's mtu is set to
>9000 :
>legendre# ifconfig wm0
>wm0: flags=0x8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 9000
>...

>	On qNAP, I have set also mtu to 9000. But iSCSI packets are not greater
>than 1448 bytes :

>23:38:56.260255 IP legendre.systella.fr.65516 >
>euclide.systella.fr.iscsi-target: Flags [.], seq 936737888:936739336,
>ack 4553905, win 4197, options [nop,nop,TS val 92106 ecr 887624208],
>length 1448


iscsi isn't any more special than other protocols. It just uses TCP
connections.

TCP segment size is calculated from the route MTU which is based on
the interface MTU when the connection is started. The segment size
is also adjusted (reduced) when errors are reported.

Did you reconnect iSCSI after the changes ?
Is there a route MTU (netstat -r will tell, a "-" means to inherit from
interface) ?
Is there anything between both machines (switch, router) that does not
support jumbo frames ?

-- 
-- 
                                Michael van Elst
Internet: mlelstv%serpens.de@localhost
                                "A potential Snark may lurk in every tree."