06-25-2013 06:51 AM
We have two main sites. Directors are connected via dark fiber. (We are using
lw SFP-s and ISL trunking, and it is working properly.)
Now we have installed a new (second) ISL trunk
between datacentres. (The new trunk has a same bandwith and cost like the first one.)
The main traffic goes till now thru the old ISL connection. This behavior is right, because
the default is the port based routing policy and DLS is not enabled.
But we want to rebalance load between ISL trunks manuallay. Without traffic
interruption. Is there any method to achieve this goal?
Thanks in advance
06-25-2013 02:12 PM
--->>>But we want to rebalance load between ISL trunks manuallay.
if I understood your question correct:
Since the ISL is Trunking formed, they do not have Influence to balance to.
06-25-2013 11:29 PM
as i understand you have now two ISL-Trunks, one without traffic.
Disable the second unused ISL-Trunk. Enable DLS and enable trunk again.
The routes are calculated new and the traffic is balanced by the DLS-Feature. Since FOS Version 6 (i do not know the correct Sub-Version) the Feature is enhanced to Lossless-DLS. So there is only a minimal Risk that you loose one Frame.
But this can not be manually maintained.
Search for Lossless DLS on the Brocade site.
06-26-2013 07:44 AM
Unfortunately we can not switch on DLS, because we are using storage replication.
Storage replication perequisites are: 1. port based routing policy, 2. DLS disabled,
3. In Order Delivery switched on.
Second problem regarding DLS is the fimware level. Directors are running on v5.3.1a FOS,
due to some compatibility reason.
My first idea was to play with link cost. I can decrease link cost on a new ISL. But I'm worried.
First, the link cost change does not take effect immediately. (I mean, that chosen
route used when one of the devices in the fabric goes offline or the fabric changes.)
Second pain point is: the different link costs can result an asymmetric load in ISL-s.
In a week or in a month all fibre traffic will use the lower cost path.
06-26-2013 07:54 AM
you can logout and login some of your initiators without changing the costs.
Port-Based Routing will put the traffic then with round robin towards both trunks.
But this is TA for the initiators.
06-29-2013 12:55 PM
You are absolutely right, I think.
But, if the new (unloaded) ISL will have less link cost, all new fabric login
must use the new path. By definition. So I can equalize ISL loads twice faster,
in best case. Of course, when we reach the 50-50% load share, we should restore default