Link Aggregation

Posted on 2011-10-31
Last Modified: 2012-05-12
Hi Experts,

I have recently setup link aggregation between 2 Juniper srx650 in cluster and 2 Ex4200 in virtual chassis with 4 physical interfaces on each device, but for some reason I am still only getting 1Gbps speed. This seems to be shared by all the servers.

Any advice is appreciated.

Question by:jimmy1829
    LVL 15

    Expert Comment

    Aggregation will allow you to bundle multiple links and load balance multiple conversations depending of the mechanism used, for example MAC, IP Addresses, Port,  but any one conversation will only use one of the available links and so is limited to that speed.

    Author Comment

    Thanks, for example, file transfer between server 1 and server 2 and file transfer between sever 3 and server 4. These two transfers should be sharing on the same link?

    LVL 15

    Accepted Solution

    In that example the transfers could be using the same link but may not.

    A better example is server traffic to multiple clients. The load balance algorithm generates a hash value which will map to one of the available links to send outgoing traffic. If based on just the source IP address, all traffic from the server will go out the same link. If based on just the destination address, then all traffic to a particular address will go out the same link but different addresses will cause the traffic to be spread across all available links. Base the loading on source and destination will combine the effects of both so that different links may be used for server1 to client1, server1 to client2, server2 to client1 and server2 to client2.

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