06-16-2009 08:22 PM - edited 03-04-2019 05:08 AM
Hi, I have one query regarding Load balancing in Etherchannel. I have many internal client which is reaching ONE server. My load balance should be on Source-Mac or Dst-Mac ? When we can use Sourcr-Mac? please help.
06-16-2009 08:48 PM
Hi
I think it should be destination based.
Thanks
Mahmood
06-16-2009 08:50 PM
When we can use Sourcr-Mac?
06-17-2009 12:03 AM
Hello Rupesh,
the exact behaviour is platform dependent more recent platforms are able to detect the traffic type and to use a different algorithm accordingly
you can check with
sh etherchannel load-balance
EtherChannel Load-Balancing Configuration:
src-dst-ip
EtherChannel Load-Balancing Addresses Used Per-Protocol:
Non-IP: Source XOR Destination MAC address
IPv4: Source XOR Destination IP address
IPv6: Source XOR Destination IP addres
this says ipv4 SA exor ipv4 DA that is fine for your scenario.
This was taken from a C4506 with cat4500-ipbasek9-mz.122-50.SG1.bin.
Hope to help
Giuseppe
06-17-2009 01:35 AM
I know the configuration part. I am only confused when to use Dst-Mac based and when to use Source-mac based??
06-17-2009 03:24 AM
With Etherchannel, you want to "mix" the Etherchannel hash attribute(s) to try to obtain the best usage of your multiple channels.
Assume you have a router Etherchannelled to a switch which has multiple hosts connected, and those hosts use the router as the gateway.
All of subnet traffic going off subnet, from the multiple hosts, will be go to the gateway's interface single MAC although come from different MACs. All traffic entering the subnet from gateway interface will be sourced from the gateway's single MAC yet likely be going to different hosts, each with different MACs.
Given just the options dst-mac and src-mac to hash on, we want to use dst-mac for traffic from the gateway to hosts, since the src-mac wouldn't change. Conversely, traffic from hosts to the gateway, we want to use src-mac since the dst-mac wouldn't change.
06-17-2009 04:40 AM
Hello Rupesh,
I tried to show you that switches can be so smart to use IPv4 parameters for load balancing of ipv4 traffic over an etherchannel:
IPv4: Source XOR Destination IP address
on a modern switch the MAC addresses are used for non IPv4 traffic as shown in my previous post.
Hope to help
Giuseppe
06-17-2009 08:11 AM
ANy specific like Many internal host & one Outside host ?
06-17-2009 08:50 AM
Hello Rupesh,
being by default the Exor of IP SA and IP DA you should get a fair balancing in your case in either direction
the exor involves the less significant bits so that an index is calculated and gives the pointer to a member link.
if the etherchannel is made of 2 links is enough one bit if 4 links by using two bits and so on.
if the number of links is odd like 3 3 bits are used and the values are associated to links (3 3 2)
Hope to help
Giuseppe
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