Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

Load Balancing- Etherchannel

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.

8 REPLIES

Re: Load Balancing- Etherchannel

Hi

I think it should be destination based.

Thanks

Mahmood

New Member

Re: Load Balancing- Etherchannel

When we can use Sourcr-Mac?

Hall of Fame Super Silver

Re: Load Balancing- Etherchannel

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

New Member

Re: Load Balancing- Etherchannel

I know the configuration part. I am only confused when to use Dst-Mac based and when to use Source-mac based??

Super Bronze

Re: Load Balancing- Etherchannel

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.

Hall of Fame Super Silver

Re: Load Balancing- Etherchannel

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

New Member

Re: Load Balancing- Etherchannel

ANy specific like Many internal host & one Outside host ?

Hall of Fame Super Silver

Re: Load Balancing- Etherchannel

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

263
Views
0
Helpful
8
Replies