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aggregation ports and round robin balancing on switches

Peter Handke
Level 1
Level 1

Hello,

I looking for round robin options and i don't see it. I looking this on others vendors and also there isn't round robin algoritm. On Linux boxes it's working fine.

I have problem when i have 2x1G aggregate interfaces and only two speaking servers. All traffic go through one pipe. There is some problem with round robin on switches ? There are some models with this options ?

thanks for help

greetings

Peter

5 Replies 5

For EtherChannels you use the command "port-channel load-balance XXX" to control how the traffic is distributed.

cadet alain
VIP Alumni
VIP Alumni

Hi,

there is no round-robin for load-balancing on etherchannels as far as I know.

Take a look here to understand how load-balancing is done: http://www.cisco.com/en/US/tech/tk389/tk213/technologies_tech_note09186a0080094714.shtml

Regards.

Alain

Don't forget to rate helpful posts.

Don't forget to rate helpful posts.

I see only:

port-channel load-balance {src-mac | dst-mac | src-dst-mac | src-ip |  dst-ip | src-dst-ip | src-port | dst-port | src-dst-port}

and:

if the data is received from the same source, then same link of the  EtherChannel is used in order to forward the data

I don't see typical round robin. I read that in old switches it was this  option but not today, there was some problem with tcp: tcp received disordered packets and it takes some time to "ordering" 

Linux:

mode

        Specifies one of the bonding policies. The default is

        balance-rr (round robin).  Possible values are:

        balance-rr or 0

                Round-robin policy: Transmit packets in sequential

                order from the first available slave through the

                last.  This mode provides load balancing and fault

                tolerance.

regards

Peter

You need to choose the option that fits your need most. And yes, RoundRobin is not available. On Layer2 the frames should not be reordered. So the load-balancing makes sure that one flow can't be split onto different channel-members.

In your setup you probably want to configure "src-dst-port" and set the Linux-bonding to "802.3ad" which is compatible to a LACP-config on a switch ("channel-group X mode active" on the member-interfaces).

On Linux box i have to use mode 0 because there is only the one with round robin balancing. All works ok when linux box is transmiting through two ports. Problem is in opposite direction when switch is transmiting - all traffic is going via one port. What exactly problem is with reordered packets ? I don't see any problem when Linux box is transmiting packets.

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