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Cross Stack LACP

Stefan Hellman
Occasional Contributor

Cross Stack LACP

Can I configure cross stack LACP on a stack with 3400cl ?
9 REPLIES
Mugilvannan
Valued Contributor

Re: Cross Stack LACP

Yes, U can. Plz refer
http://www.hp.com/rnd/products/switches/ switch3400series/features.htm
If U need a helping hand, U will find one at the end of your arm
Ardon
Trusted Contributor

Re: Cross Stack LACP

Stefan,

Not sure what you mean by "Cross Stack LACP"?
Can you elaborate your question please.

You want to interconnect a Physical Stack of 34XX Switches but not by a single link but by means of LACP Trunks?

Regards, Ardon
ProCurve Networking Engineer
Stefan Hellman
Occasional Contributor

Re: Cross Stack LACP

If i set up a stack of 2 or more 3400, can I use 1 port from each to for a LACP-aggregation to another unit?
Ardon
Trusted Contributor

Re: Cross Stack LACP

Hi Stefan,

No, Trunks have to "coterminous" or in other words. A Trunk has to run Point-to-Point so starting at Switch 1 and running ONLY to ONE remote Switch.
It is not supported to "split" a Trunk, one strand running to Switch 2 and the other strand running to Switch 3 both originating from Switch 1.

It is mentioned in the 34XX Management and Configuration Guide page 12-3. I quote:

Port Connections and Configuration: All port trunk links must be point-to-point connections between a switch covered by this guide and another switch, router, server, or workstation configured for port trunking. No intervening,
non-trunking devices are allowed.

Regards, Ardon
ProCurve Networking Engineer
rochan
Occasional Visitor

Re: Cross Stack LACP

Will the limitation be fixed in a newer version of firmware? Do any other HP switches/routers support LACP across different devices?
Is there any other switches which support stacked LACP?
Regnar Bang Lyngsø_2
Frequent Advisor

Re: Cross Stack LACP

I would be surprised if it is coming on any current Procurve swiches (but I like surprises :-) ).

Cisco 3750 is able to do it (from 12.2(25)SEC release notes):

⠢ Cross-Stack Link Aggregation Control Protocol (LACP)-Although the Cisco Catalyst 3750 switches have supported cross-stack Cisco EtherChannel® configurations (consisting of ports on multiple stack members) since their initial release, they currently require static, manual configuration; use of the LACP for negotiated Cisco EtherChannel formation is supported only for ports on a single switch. This feature extends LACP support so that ports can be spread across stack members.
Sergej Gurenko
Trusted Contributor

Re: Cross Stack LACP

I suppose you can use HP-Messhing, if you want some kind of cross stack Active-Active load balancing.

This document explains configuration in details http://www.hp.com/rnd/pdfs/Switch_Meshing_Paper_Tech_Brief.pdf
rochan
Occasional Visitor

Re: Cross Stack LACP

Thank for the reply, I've had a look through the information. I assume that each of the individual switches can be connected to seperate routers which eventually route back to the same point in the network?
i.e. This will provide LAG redundancy over muliple LAG switches acting as one?
Sergej Gurenko
Trusted Contributor

Re: Cross Stack LACP

From the STP standpoint meshed switches domain looks like one big switch. That mean you can connect meshed domain to the different upstream routers. Additional techniques needed to enable router load balancing (end users using different default gateways or Cisco Gateway Load Balancing Protocol (GLBP))
Can you describe size of you server farm network infrastructure?