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Contributor
Posts: 23
Registered: ‎06-04-2004

DPS and trunking

Hi all,

I would like to use exchange based routing (dps). We have  the following configuration :

4 Brocade DCX, FC-48 blades 8 Gb;

2 fabrics, each fabric = 2 DCX and 4 isl between DCX via dwdm links

IT Site 1                                                 IT Site 2

**********                                                **********

DCX                                                        DCX

                  dwdm             dwdm

                  dwdm             dwdm

DCX                                                        DCX

We have two different way between Site 1 and Site 2, one way takes 20 km and the other way takes 23 km. I have in each fabric 4 ISL's and I would like to define two trunks of 2 ISL's (taking the same way) in each fabric.

My question is : Can I use DPS between the two trunks (despite the distance difference) ?

Thanks a lot for your help.

Kind regards.

Valued Contributor
Posts: 931
Registered: ‎12-30-2009

Re: DPS and trunking

Yes you can use DPS with trunks of different lengths.

Beware though that the ISL length within a trunk are as equal as possible.

A difference more the approx 300 meters between trunkmembers could have performance implications.

In your case you should form a trunk with ISL from the 20k OR 23k path only.

If you want redundancy in the paths then form 2 trunks per fabric with one taking the 20k path and the otherone taking the 23k path.

External Moderator
Posts: 4,862
Registered: ‎02-23-2004

Re: DPS and trunking

Pierre,

if I understand correctly:

You can not build a ISL as DSP and Trunking at same time.

TechHelp24
Valued Contributor
Posts: 931
Registered: ‎12-30-2009

Re: DPS and trunking

DPS (or Exchange Based Routing) and Trunking at the same time is supported according to the CFA280 course docs, but can be found in other docs as well

Dynamic Path Selection
Dynamic Path Selection (DPS) is also known as Exchange-based routing. DPS is where
exchanges or communication between end-devices in a fabric are assigned to egress ports in
ratios proportional to the potential bandwidth of the ISL or trunk group. When there are
multiple paths to a destination, the input traffic will be distributed across the paths in
proportion to the bandwidth available on each of the paths. This improves utilization of the
available paths, reducing the possibility of congestion on the paths. Every time there is a
change in the network (which changes the available paths), the input traffic can be
redistributed across the available paths.

source: http://www.redbooks.ibm.com/redbooks/pdfs/sg247922.pdf

External Moderator
Posts: 4,862
Registered: ‎02-23-2004

Re: DPS and trunking

is new to me, but I will not insist....

TechHelp24
Contributor
Posts: 23
Registered: ‎06-04-2004

Re: DPS and trunking

Thanks a lot for your good answer.

Best regards,

Pierre

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