LACP across two HP 2824 switches

[jervolino]

We have two 24 port HP 2824's and we are using them for a iSCSI SAN. I want to be able to do an LACP trunk across them, I have them connected to eachother via a 2Gb connection setup in the 'trunk' configuration.

Thanks in advance,
Joe.

[Geir Olav Skei .]

Hello Joe,

If I understand you correctly, you are wondering how to configure a trunk?

Basically, you have two ways of establishing a trunk on the ProCurve devices.
Statically defined or dynamically using LACP.

Static config:
(config)# trunk 23-24 trk1 trunk
Here port 23 and 24 will be replaced by the logical interface trk1, which can be configured afterwards. (e.g. assigned membership in different vlans)

Dynamic config:
Dynamic LACP, where the software deals with the whole trunk configuration, needs ports on one switch to be LACP active, while the other switchs ports, remain as LACP passive (Default).

Basically, ports which are LACP active, will negotiate for a LACP trunk when they come online.
To set ports as LACP active: (config)# interface ethernet 23-24 lacp

Note: Dynamically established trunks will only operate in default vlan, even if port 23-24 reside as untagged members in a different vlan, the trunk-entity will be moved to default vlan.


Hope this helps,
if not, please elaborate on what you are trying to accomplish. =)

--Gos

[jervolino]

Geir,

Thanks for the response, That is somewhat what I was looking for. I was looking more along the lines of how you configure an LACP trunk between two switches i.e. (Switch1 - Port 24 and Switch2 - Port 24 configured to be an LACP trunk), to make switching paths redundant and also get combined throughput.

Thanks,

Joe.

[Geir Olav Skei .]

Hi Joe,

Ok, the configuration for a static lacp trunk is very simple.
However, to provide redundancy and load sharing, you must of course use two or more links.

Switch_1(config)# trunk 23-24 trk1 lacp
Switch_2(config)# trunk 23-24 trk1 lacp

Done.

The logical interface "trk1" is only locally significant and does not need to match on both sides of the link.

--Gos

[jervolino]

Ok, let me recap so I make sure that i have this understood.

you can't actually to an LACP trunk across two switches but you could do a trunk on each switch, which would provide your 2Gb of bandwidth and also give you redundancy.

Is this just because they are edge switches and not core switches that use blades?

Thanks again for all the info, very helpful.

Joe.

[Geir Olav Skei .]

Both, yes and no.

This is the difference between LACP trunk and trunk;

LACP trunk: The software creates the trunk.
Trunk: You create the trunk.

The functionality of those two trunks are identical (bandwidth & Redundancy) - it is just different ways of configuring and setting it up. =)
- (Except that a LACP trunk only works in vlan 1)
The procedure of creation of trunk on core and edge switches are also the same.

--Gos

[Richard Brodie_1]

I'm not sure you are talking about the same thing.

Joe, if you mean "Can I connect two ports on an end node to two different switches and make it an LACP trunk?" then the answer is, no, plain old LACP does not do that.

Nortel has a proprietary method for split trunking: I don't know if HP has an equivalent, even on their higher end equipment.