topic Re: Problem with stack and LACP in Switches, Hubs, and Modems

Problem with stack and LACP

fsp_1 — Wed, 06 Aug 2008 09:43:07 GMT

Hi,

We're trying to configure LACP for a Procurve 2810 stack of switches. We would like to connect one port in switch A, and other one in switch B, with another stack of switches in the other end.

Is it possible? How? I know that it's possible with Cisco switching, but I had not tried it before with HP Procurve.

Maybe with a firmware upgrade? Now we're running N11.06

If it was not possible, have we got any other possibility? Maybe meshing?

Thanks

Re: Problem with stack and LACP

Jarret Workman — Wed, 06 Aug 2008 18:52:13 GMT

Hi FSP,

If I understand correctly, it sounds like we are trying to configure link aggregation using LACP to have one link go to switch A and the second link connect to switch B.

With link aggregation (either LACP or HP trunks), the connections must be co-terminous (begin and end at the same place).

There is some terminology difference between what Cisco defines as a "trunk" versus ProCurve. A trunk in Cisco defines a port that is carrying multiple vlans whereas a trunk in ProCurve terminology is link aggregation.

If the goal is to pass multiple vlans across these two links, this can be accomplished with vlan tagging on the ProCurve units. You would have one untagged (native) vlan, and each of the other vlans would be tagged (trunk).

Regards,

Jarret

Re: Problem with stack and LACP

fsp_1 — Wed, 06 Aug 2008 21:41:57 GMT

Hi Jarret, thanks.

The idea is not carry traffic for more than one VLAN. The idea is aggregate the amount of traffic that we receive from the other end, and also have a redundancy if one of these two links, or one of the switches has a failure.

I know that Catalyst 3750 permits it, but I don't know if HP Procurve makes it too.

Thanks

Re: Problem with stack and LACP

Mohieddin Kharnoub — Thu, 07 Aug 2008 05:31:37 GMT

Hi

You can do that by creating Aggregated Links between the Switches, and ALLOW me to call this :
Cascading , not Stacking.

Switch1 Switch3
|| ||
|| ||
|| ||
Switch2 Switch4

If you decided to connect Switch1 to Switch2 with 2 Ports (at least), its called TRUNK with all vendors except Cisco that call it Etherchannel.

This Trunk is physically 2 ports but logically one port after Creation.

You can also connect group1 with group2 similarly, example (link is another TRUNK with at least 2 ports but shown as one link):

Switch1------------Switch3
|| ||
|| ||
|| ||
Switch2------------Switch4

Or you can connect Switch1 to Switch4, Switch2 to Switch3 ..... etc.

Good Luck !!!

Re: Problem with stack and LACP

Renico — Thu, 07 Aug 2008 05:39:55 GMT

Hi FSP,

I not sure if I understand you correctly, but can't you configure spanning-tree on both stacks do provide redundant links?

Re: Problem with stack and LACP

fsp_1 — Thu, 07 Aug 2008 10:03:08 GMT

Hi,

The idea is:

SW_HP1------------SW_Cisco1
| link1 |
| |
| |
SW_HP2------------SW_Cisco2
link2

I don't manage Cisco switches, that have the link to my switching connected via etherchannel redundant link.

One possible solution in mi side, would be implement a simple spanning-tree configuration, but my customer would like to aggregate the bandwith of link1 and link2.

Thanks.

Re: Problem with stack and LACP

Mohieddin Kharnoub — Thu, 07 Aug 2008 12:18:06 GMT

Hi

Aggregate the bandwidth of both Link1 and Link2, means using MSTP with multiple instances and different Vlans in each.

Once you enable Spanning-Tree, Link1 or Link2 will be blocked, so MSTP is the solution to utilize both links in this topology.

Good Luck !!!