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LACP vs Trunk

 
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basti23
Occasional Advisor

LACP vs Trunk

Hi 

i am trying to interconnect 2 x 2920 Switches, i am a little bit confused about difference between trunk and (static) lacp config. Discussion LACP vs Trunk states that LACP does not tag the traffic, means the ports can only be on one VLAN.

My config looks like following:

trunk 1/45,1/46 trk1 lacp

vlan 999
   name "MGMT"
   untagged 1/1-1/44, 1/47-48, Trk1
   no ip address
exit
vlan 2
   name "PC"
   tagged Trk1
   no ip address
   exit
vlan 3
   name "Printer"
   tagged Trk1
   no ip address
   exit
vlan 4
   name "Multimedia"
   tagged Trk1
   no ip address
   exit
vlan 5
   name "WLAN"
   tagged Trk1
   no ip address
   exit

spanning-tree Trk1 priority 4

This configuration works fine so far, so LACP is tagging VLANs on the Trk1. So what is the difference between trunk 1/45,1/46 trk1 lacp and trunk 1/45,1/46 trk1 trunk

thanks

 

 

 

 

3 REPLIES 3
Vince-Whirlwind
Honored Contributor
Solution

Re: LACP vs Trunk

Ignore that discussion, especially the first reply, which is nonsense.

"Trunk" in this context just means link aggregation and has nothing at all to do with 802.1q.

The difference between Trunk and LACP in this context is just that they use two different methods for create the aggregated link. I usually go with "Trunk" if I'm using Procurve switches, LACP otherwise.

Linkk
Frequent Advisor

Re: LACP vs Trunk

It has nothing to do with VLANs.

LACP uses the 802.3ad protocol to negotiate the interfaces with the remote device. It uses hash algorithms for load-balancing and can be increased or decreased in the number of interfaces without any impact to the logical link. It also detects if the other side of the interface is misconfigured and stops sending packets on misconfigured interfaces to prevent packet loss. You may know it from Cisco as an EtherChannel. 

"trunk" just puts this interfaces together but does not negotiate anything with the other site. It is mandatory that the other site is also configured as a trunk for the link to be working.

I usually go with LACP as often as possible, since it is really easy to implement and brings only positives.
Some server (f.e. VMWware ESXi ) can not "speak" 802.3ad natively (or only with the biggest license), so I have to use static trunks or switch independent load-balancing.

basti23
Occasional Advisor

Re: LACP vs Trunk

thanks Linkk and  Vince-Whirlwind for your help, really appreciate!!!