Wired Intelligent Edge

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  • 1.  LACP vs Trunk

    Posted Jun 01, 2017 02:43 AM

    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

     

     

     

     



  • 2.  RE: LACP vs Trunk

    Posted Jun 05, 2017 10:55 PM

    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.



  • 3.  RE: LACP vs Trunk

    Posted Jun 07, 2017 01:21 PM

    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.



  • 4.  RE: LACP vs Trunk

    Posted Jun 08, 2017 11:38 AM

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