[f-nsp] BigIron RX LAG load sharing behaviour

[Dana]

Hi all,

I have noticed a little problem with our LAG configurations in our 
Bigiron RXes. The problem description is as follows:

We have configured a LAG of two or more ports. From time to time we are 
getting a high utilization port message from our monitoring system on 
one of the two/more ports in that LAG. Thus, it seems that the software 
does not share the traffic evenly amongst the available ports.

After reading the manual, I understand that there is no way we can 
manipulate the load-sharing method of our LAGs. BigIron RXes only 
load-share using HASH-BASED method. Although Foundry/Brocade claims that 
this method should do the job properly, it is not the case in our 
network. Let me give you some lines to show the problem:

lag "trunk-1" static
  ports e 2/7 to 2/8
  primary-port 2/7
  deploy

#sh int e 2/7 | i util
   300 second input rate: 155247818 bits/sec, 39455 packets/sec, 15.90% 
utilization
   300 second output rate: 25029300 bits/sec, 11300 packets/sec, 2.61% 
utilization

sh int e 2/8 | i util
   300 second input rate: 189413832 bits/sec, 44085 packets/sec, 19.36% 
utilization
   300 second output rate: 482937687 bits/sec, 79502 packets/sec, 49.05% 
utilization

As you can see above, the output rate (from BIRX to an FWSX) has a ratio 
of 49% vs 2%. However, if you look at the input rate (from FWSX to 
BIRX), it has more or less the same amount of traffic 19% vs 15%.

My question is now, is there anyway we can do in the BIRX to get the two 
ports more balanced?  I hope some of you has experienced the same 
problem and could share the solution/trick with me.

Thanks in advance.


-- 
Dana