FCIP issues with SAN replication

["Chandler, Mel" <melchandler () firstam com>]

Greetings all,

 

My company is attempting to perform replication from one HP EVA SAN
array to another HP EVA SAN array across the WAN.  We have a metro
Ethernet connection between the two with one Gigabit of shared
bandwidth.  We share the bandwidth with our other business units, with
no QoS in place, but we have been told that the pipe has never been
completely saturated, and we're not rate limited.  The SAN arrays are on
4Gbps fiber channel brocade switches.  There are two devices called
MPX110's that send the data from fiber channel to Ethernet.  Each MPX
has redundancy groups they perform replication for, and although they
have two Ethernet and two fiber channel ports on each, we only use one
on each.  Each MPX110 has a path they perform replication for to their
counter parts on the other side.  It is my understanding they negotiate
a tunnel between them, Fiber Channel over IP.  They're each on their own
6509 which have a uplinks to a 3750 and that goes across the metro
Ethernet to a 3560 on the other side, then up to a 3560 acting as the
core and out to two 3560's with an MPX on each one.

 

Now the problem, although we have one gigabit of bandwidth, they'll only
use about 13Mbps of it each, we've verified this with iperf.  Each
connection we'll only take 13Mbps of bandwidth, parallel tests show each
connection gets 13Mbps of bandwidth.  The HP engineer told us that at
> 5Mbps we get approximately 1.3Mbps of actually data, which means that
FCIP has 80% over head?  Can that be right?  The big huge problem is
that after running for several hours they'll eventually just die and
have to rebooted to start replicating again.  They're already on the
latest firmware (2.4.4.1).  The only error we get from the statistic
screen of the MPX's says they're getting TCP timeouts.

 

I've performed captures on both sides' MPXs' and the errors I see in a
60 sec sample are FCP malformed packets (~4300), duplicate ACK's (~41),
previous segment lost (~3), fast retransmission (~3).  When HP was
questioned about the FCP malformed packets they stated that they use a
proprietary protocol and that wireshark wouldn't be able to decode it.
I've since searched for this protocol but can find no references to it
anywhere.  The other errors seem so minor and few it would be hard to
believe that they're impacting the data stream that much if at all.

 

I'll include a small sample of the captures, if it lets me.

 

Thanks in advance for your assistance.

 

Chandler Bing

 

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