EtherChannel C2950 and C3560

[mark_Bayliss]

Hey Everyone,

What is the best way to configure EtherChannel for performance between a C2960 and a C3560. It will be used for trunking as well.

Regards,

Mark

[Istvan_Rabai]

Hi Mark,

The best way to configure Etherchannel for performance is to use the appropriate load balancing.

The best load balancing method depends on your configuration.

You can load balance on:

- destination ip address or source ip address or both

- destination mac-address or source mac-address or both

- destination port or source port or both

The problem with your configuration is that C2960 is capable only for load balancing on mac-addresses.

C3560 is capable for load balancing on mac-addresses or on ip addresses.

In one traffic direction you can configure load balancing on C2960 on destination mac-address or source mac-address or both.

In the other direction you can configure load balancing on C3560 on mac-addresses or on ip addresses, so you have more flexiblity.

Don't forget to use the switchport command on the C3560 and the trunking configuration.

If you have the specific mac-addresses and ip addresses, I can help you decide which is a better load balancing method.

Cheers:

Istvan

[alshamlan]

Hi dear,

I have same senario C2950 with c3560 and I want to do an etherchannel between them. I configura two port in eath of then interconnected with each other as trunk port.

The question is how I can make load balance as some traffic move to both link not one of them. ? I have both link up as redudncy but not as load balance.

Regards

MHS

[Florin Barhala]

Cisco quote: "The Catalyst 2950/2955 series switch can support up to eight compatibly       configured Ethernet interfaces in an EtherChannel. The EtherChannel can provide       full-duplex bandwidth up to 800 Mbps (Fast EtherChannel) or 2 Gbps (Gigabit       EtherChannel) between your switch and another switch or host. The number of       EtherChannels has the limit of six with eight ports per EtherChannel.

Issue the port-channel load-balance {dst-mac |       src-mac} global configuration command in order to configure the       load-balance and forward method.

Note: The default port is used to transmit traffic, such as Spanning Tree           Protocol (STP), multicasts, and unknown unicasts. The default port can be           identified from the output of the command show etherchannel           summary by a notation of d."

[glen.grant]

A given ip conversation will only flow down one of the links  ,there is no way around that

.

[andtoth]

Hi,

The following documentation will definitely help you to understand how to achieve better Etherchannel loadbalancing with examples of how it's actually working.

Understanding EtherChannel Load Balancing and Redundancy on Catalyst Switches

http://www.cisco.com/en/US/tech/tk389/tk213/technologies_tech_note09186a0080094714.shtml

Best regards,

Andras

[alshamlan]

Dears,

What si the meaning of Load Balance? The traffic should flow in both link based on load balance policy.

C2950  support L2 load balance

BAH-KLM-BM-SW(config)#port-channel load-balance ?
   dst-mac  Dst Mac Addr
   src-mac  Src Mac Addr

while

C3560 support L2 and L3 load balance.

  dst-mac  Dst Mac Addr
   src-mac  Src Mac Addr

  dst-ip      Dst IP Addr
   src-ip      Src IP Addr

what the policy that I should apply on both switch to have a load blanace to flow the traffic on both link.

Regards

MHS

[andtoth]

Understanding EtherChannel Load Balancing and Redundancy on Catalyst Switches

http://www.cisco.com/en/US/tech/tk389/tk213/technologies_tech_note09186a0080094714.shtml

[alshamlan]

Dear Andras,

Thanks for the documents. I applied the load balance policy and still I ma seeing that the traffic is going through one port.

I want to apply the poicy in such away That if I have two ports each 10 MB, i want to get 20 MB as sumation of them.

Regards

MHS

[andtoth]

Hi Mahmood,

The load-balancing policy will need to be chosen based on your traffic patterns. It really depends on how traffic is flowing in your network.

Try changing it from one to another and see if the balance between the links is better then, as explained in the documentation.

Best regards,

Andras

[cadet alain]

Hi,

traffic between 2 same machines will always use one port only whatever load-balancing method you use.

Regards.

Alain.

[glen.grant]

   You have to understand the a port channel is just a bigger pipe for all traffic .  A given single ip conversation will "only" flow down a single port in that etherchannel , it will not get distributed across multiple ports.   So a given ip conversation may get sent down one port in the port channel while a different ip conversation may  get sent down a different   port int he port channel depending on the load balance algorithim.So in essence say if you have a 4 port fast ethernet ehterchannel you have a total of 400 meg of bandwidth available ,  a single given conversation actually only has access to 100 meg of that 400 meg total because a given conversation will only flow down one port , no way around that.  Your only option on a channel between switches is to play with the load balancing algorithim so that you get a more equitable distribution of traffic ,   it will never be perfectly balanced between the ports...