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Community Member

Etherchannel load-balancing

Hi

I have problem with in choosing method etherchannel load-balancing

server ----Switch1-----EtherChannel-----Switch2----Router1----more hosts

SW1 3550 src-mac SW2 3550 src-mac

SW1 3560 src-dst-ip SW2 3560 src-dst-ip

is it good ?

Regards

8 REPLIES
Hall of Fame Super Silver

Re: Etherchannel load-balancing

Hello Michal,

yes it should work in any case the operation is an Exor of last significant digit:

if the hosts and their MAC addresses are not all even or not all odd you should have some load sharing.

Of course you cannot expect a 50/50 ratio in usage.

Hope to help

Giuseppe

Super Bronze

Re: Etherchannel load-balancing

For the 3560, yes, for the 3550 no. For the 3550, its two load-balance options can not balance traffic since server and router MACs remain the same. For the 3560, server IP remains the same, but host IPs vary. You could also use the dst-ip (sw1) and src-ip (sw2) options.

[edit]

PS:

BTW, if the problem was servers (plural) not server (singular), then you could also use src-mac (sw1) and dst-mac (sw2) on the 3550s.

Community Member

Re: Etherchannel load-balancing

HI

But in 3550 src-mac = src-dst-ip

I can't using this method.

Michal

Super Bronze

Re: Etherchannel load-balancing

I'm was confused by your response, still might be.

I don't work with 3550s, and had only checked its load balancing features (along with 3560 Catalyst switches) here: http://www.cisco.com/en/US/tech/tk389/tk213/technologies_tech_note09186a0080094714.shtml#cat2950_3550.

The 3550's supports both L2 and L3 Etherchannels. From your post, I was assuming you were using the switches just in L2 mode, especially since you had one in front of "router1". If you use them (3550s) at L3, then "But in 3550 src-mac = src-dst-ip" applies, i.e. the src-mac option enables src-dst-ip, which like it does on the 3560, would work well.

Since you wrote "I can't using this method.", I believe you've confirmed my assumption that you intended a L2 Etherchannel, and in this case, you can't load balance to/from a single pair of MACs (i.e. one server and one router).

Community Member

Re: Etherchannel load-balancing

Yes I'm using etcherchannel L2. I'm understand below situation

server--SW1---EtherChannnel(Layer2) ---SW2--more host

SW1 3550 dst-mac SW2 3550 src-mac

But when SW2 will be 3560 I can using src-mac or src-dst-mac . It's right?

Generaly , when We used etherchannel on L2 we based on MAC when etherchannel on L3 we based on IP ? Its truth.

Cisco Employee

Re: Etherchannel load-balancing

Hi,

You wrote: "Generaly , when We used etherchannel on L2 we based on MAC when etherchannel on L3 we based on IP ?"

Personally, I would put it this way: you balance according to that parameter which provides you with the best variance and thereby the best traffic distribution. On any kind of EtherChannel, it might be IP or MAC, source or destination - that really depends on your traffic pattern. No universal recommendations here...

Best regards,

Peter

Super Bronze

Re: Etherchannel load-balancing

"Yes I'm using etcherchannel L2. I'm understand below situation

server--SW1---EtherChannnel(Layer2) ---SW2--more host "

That's a different situation from your original post, since there's no router between sw2 and the other hosts. Then you could, as your write use: "SW1 3550 dst-mac SW2 3550 src-mac".

"But when SW2 will be 3560 I can using src-mac or src-dst-mac . It's right? "

If you use a 3560, from the reference I provided, all the Etherchannel balancing options are allowed regardless of L2 or L3 Etherchannel. If using a 3560, they you would want to balance using one of the IP options.

"Generaly , when We used etherchannel on L2 we based on MAC when etherchannel on L3 we based on IP ? Its truth."

Not always, depends on devices and topology. Howerver, if the Etherchannel is routed p-2-p, it's likely there's only a single MAC being used so that's why the IP based options would be chosen.

Community Member

Re: Etherchannel load-balancing

Thanks

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