[NCLUG] Networking Issue

[Michael Coffman]

On Mon, 5 Aug 2013, Matt Kassawara wrote:

> Do both variants of configuration A have the same problem?

Yes.

> Do any of the switches in question indicate the reason for discards?

Only the hp5412(b) listed is showing discards.   All it says from what I 
can tell is 'Tx discards'

> Did you configure end-to-end support for jumbo frames?
Jumbo frames are not enabled.

> Can you provide more details on "10g mesh" between the 5412s?

We have 3 5412's that are all connected via 10g and have HP's meshing
enabled.   What kind of detail are you looking for?

>
>
> On Mon, Aug 5, 2013 at 5:14 PM, Michael Coffman
> <coffman at ftc.avagotech.com>wrote:
>
>>
>> I don't do networking and our corporate networking group has been cut so
>> thin, they don't do much networking anymore either :(
>>
>> This is not a linux problem, but I know there are folks on this list that
>> have deep networking experience.  I'll try to describe the problem as best
>> as I can in ascii.
>>
>> *NA = NetApp
>> *CS = Compute Server
>>
>> #----  A
>> NA -10g-> hp5412(a) -10g mesh-> hp5412(b) -1g-> CS
>> NA -10g-> hp5412(a) -10g mesh-> hp5412(b) -4g trunk-> hp2500 -1g-> CS
>>
>> o The read path to the compute server is very slow 20-30MB/s
>> o The write path to the NetApp is close to wire speed 110-130MB/s
>> o The hp5412(b) switch is having thousands of discards at the port to the
>>   CS system
>> o Enabling flow control on all the switches on the mesh almost
>>   completely eliminates the discards and increases read performance, but
>>   hurts write performance
>> o Reversing the flow above does not have the same performance problems
>> o Reversing the flow above does not cause discards on hp5412(a)
>>
>> #---- B
>> NA -10g-> hp5412(a) -10g mesh-> hp5412(b) -10g-> hp5800 -1g-> CS
>>
>> o The above scenario has no performance issues.
>> o Still seeing discardson hp5412(b) due to other traffic on the switch
>>
>> #---- C
>> NA -10g-> hp5412(a) -1g-> CS
>> NA -10g-> hp5412(a) -1g-> hp2500 -1g-> CS
>>
>> o The above scenario works fine.
>> o The hp5412(a) is not seeing the discards that hp5412(b) does.
>>
>> Any ideas on how to go about trouble shooting this?
>>
>> I am not looking for free answers to this problem here, I would be glad to
>> talk to someone about doing some network consulting.  Also any pointers to
>> a networking consultant/guru would be greatly appreciated.
>>
>> Thanks.
>> -MichaelC
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-MichaelC