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Wireless Networks Thread, Redundant Network links in Technical; Hi All. I wish to set up redundant network links. We are upgrading 2x 1GB/s link to 10GB/s and would ...
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    Redundant Network links

    Hi All.
    I wish to set up redundant network links.

    We are upgrading 2x 1GB/s link to 10GB/s and would like to have the 2x gb/s as failover.

    I set up the old 2x1GB/s connection using LACP aggregated links on HP E5500/E4800, but it seems that LACP cannot work over different speed connections (so said the internet, and it didn't work when I tried it)

    What alternative can I use to LACP to use the 1GB/s as a resilient link if my 10GB/s fails?

    config is here if it helps:

    Code:
    interface Ten-GigabitEthernet1/2/1
     description Uplink-To-Core
     port link-type hybrid
     port hybrid vlan 20 100 tagged
     port hybrid vlan 1 untagged
     broadcast-suppression pps 3000
     port link-aggregation group 1
    #
    return
    [Maths-English-4800G-Stack-Ten-GigabitEthernet1/2/1]int g1/0/26
    [Maths-English-4800G-Stack-GigabitEthernet1/0/26]dis this
    #
    interface GigabitEthernet1/0/26
     description Uplink-To-Core
     port link-type hybrid
     port hybrid vlan 20 100 tagged
     port hybrid vlan 1 untagged
     broadcast-suppression pps 3000
     port link-aggregation group 1
    #
    return
    [Maths-English-4800G-Stack-GigabitEthernet1/0/26]int g2/0/26
    [Maths-English-4800G-Stack-GigabitEthernet2/0/26]dis this
    #
    interface GigabitEthernet2/0/26
     description Uplink-To-Core
     port link-type hybrid
     port hybrid vlan 20 100 tagged
     port hybrid vlan 1 untagged
     broadcast-suppression pps 3000
     port link-aggregation group 1
    Code:
    
    dis link-aggregation verbose 
     
    Loadsharing Type: Shar -- Loadsharing, NonS -- Non-Loadsharing 
    Port Status: S -- Selected, U -- Unselected 
    Flags:  A -- LACP_Activity, B -- LACP_Timeout, C -- Aggregation, 
            D -- Synchronization, E -- Collecting, F -- Distributing,  
            G -- Defaulted, H -- Expired
    
    Aggregation Interface: Bridge-Aggregation1
    Aggregation Mode: Dynamic
    Loadsharing Type: Shar
    System ID: 0x8000, 4001-c64d-9c00
    Local: 
      Port             Status  Priority Oper-Key  Flag 
    --------------------------------------------------------------------------------
      GE1/0/26         U       32768    6         {AC}
      GE2/0/26         U       32768    6         {AC}
      XGE1/2/1         S       32768    7         {ACDEF}
    Remote: 
      Actor            Partner Priority Oper-Key  SystemID               Flag   
    --------------------------------------------------------------------------------
      GE1/0/26         177     32768    3         0x8000, 001a-c132-d980 {AC}
      GE2/0/26         3       32768    3         0x8000, 001a-c132-d980 {ACEF}
      XGE1/2/1         199     32768    24        0x8000, 001a-c132-d980 {ACDEF}

  2. #2

    SYNACK's Avatar
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    If you are doing this soley via switching I think the standard way is to use STP and have it negotiate to have only one link active, the 10 or the 2 at any one time. It should pick the best speed link as primary but you may need to define port priority and you will definatly need to turn it on to full long negotiation STP as its a core link. This is actually what STP was initially designed for before the culture of user sabotage became all the rage.

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    I'll take out the aggregation, LACP etc tomorrow and look into port priority for STP.
    Thanks for the pointer.

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    You should be able to leave agregation on and have port priority set on the bundle if it does not do it automaticlly I think. Depends on the implementation but the link cost is based on speed and hops unless you tell it different usually.

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    STP link selection is based on link cost (cumulative cost if there are multiple links) to the root bridge (switch). Port priority only comes into play with equal cost links. However, if all of the STP bridges (each switch) are running at the default bridge priority of 32768 then it's based on MAC address. You may find an unusual switch is the Root Bridge for the entire network.

    As an example our core switch runs at the lowest STP bridge priority so it becomes the root bridge, the secondary core switch runs at the second lowest, and then all access layer run at the default value. So all of the STP calculations in our network are based on the link cost of getting from the remote switch to the Root Bridge. As the secondary core is also lower than the default priority if either of the cores go down we don't find ourselves with a little access switch finding itself as the root bridge.

    So in your example if you have your two 10gb aggregated as a 20gb link and your two 1gb aggregated as a 2gb spanning tree would use the 20gb link as it's the lowest cost and it would hold the 2gb link down as a redundant link.

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    +1 for STP.

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