Ether channel bundling

[s.kanth]

1. In Etherchannel  2,4,8 (suppose SwitchA 4 ports and SwitchB 4 ports ,become 8port ether channel bundle) channel bundle is redundant and more efficient.But if any of the link goes down, we will have 6 channel then isn't it efficient.

2. Etherchannel can be confired on L3(3550 switch) and L2 (2950 Swithc) together but how traffic is allowed, 3550 is confired on IP address and L2 is not.

Any help,would greatly be appreciated.

Thanks

Sri

[Ganesh Hariharan]

1. In Etherchannel  2,4,8 (suppose SwitchA 4 ports and SwitchB 4 ports ,become 8port ether channel bundle)
channel bundle is redundant and more efficient.But if any of the link
goes down, we will have 6 channel then isn't it efficient.
2.
Etherchannel can be confired on L3(3550 switch) and L2 (2950 Swithc)
together but how traffic is allowed, 3550 is confired on IP address and
L2 is not.
Any help,would greatly be appreciated.
Thanks
Sri

Hi Sri,

Fast EtherChannel provides parallel bandwidth of up to 800 Mbps (400-Mbps full duplex) between a switch and a router, host, or another switch by grouping multiple Fast Ethernet interfaces into a single logical transmission path.

Fast EtherChannel segments must be contiguous ports on a Fast EtherChannel-capable Fast Ethernet switching module. You can configure Fast Ethernet ports into Fast EtherChannel groups containing two or four ports, yielding 400- or 800-Mbps bidirectional bandwidth, respectively.

Gigabit EtherChannel provides parallel bandwidth of up to 8 Gbps (4 Gbps full duplex) between a switch and a router, host, or another switch by grouping multiple Gigabit Ethernet interfaces into a single logical transmission path,so if 6 ports are there in a bundle then also you have surplus bandwidth in bundle to handle the load that wont give that much problem.

Ether channel can be configured in L3-L2 fashion, routing can be done by providing a gateway to l3 interface of etherchannel to alll host in L2 switch and from there for outside routing via dyanmic or static with outer world.

Hope to Help !!

Ganesh.H

[s.kanth]

Thanks for your brief explanation ,I understand about Megabit,Gegabit bandwidths and L2and L3 traffic fanda.

So if any one of the link goes down on 8port Fast etherchannel,I get 300-Mbps bandwidth.

Can 6 ports be configured as Etherchannel or is there any limitation (2 to the power links like 2,4,8,16)?

[Jon Marshall · Accepted solution]

s.kanth wrote:
Thanks for your brief explanation ,I understand about Megabit,Gegabit bandwidths and L2and L3 traffic fanda.
So if any one of the link goes down on 8port Fast etherchannel,I get 300-Mbps bandwidth.
Can 6 ports be configured as Etherchannel or is there any limitation (2 to the power links like 2,4,8,16)?

You can use any number of links that you want in the etherchannel with the the maximum being 8 so odd numbers such as 3,5,7 are fine.

Not sure i fully understand about the L2/L3 question.

There are 2 types of etherchannel - L2 and L3.

L2 is the commonest in use and this is simply a bundle of physical links that are configured as switchports. So you could have a L2 etherchannel between the 3550 and the 2960 switch in vlan 10 and then on the 3550 have a L3 vlan interface. This would work fine. Note that all the ports on both switches are still L2 switchports and the logical port-channel interface is a L2 interface ie. a switchport.

L3 is when you change the physical links from L2 switchports to routed links and then you would have the IP address on the logical port-channel interface itself.

Jon

[Ganesh Hariharan · Accepted solution]

Thanks for your brief explanation ,I understand about Megabit,Gegabit bandwidths and L2and L3 traffic fanda.
So if any one of the link goes down on 8port Fast etherchannel,I get 300-Mbps bandwidth.
Can 6 ports be configured as Etherchannel or is there any limitation (2 to the power links like 2,4,8,16)?

Hi,

Yes you can have 6 port etherchannel but the Cisco-proprietary hash algorithm computes a value in the range 0 to 7. With this value as a basis, a particular port in the EtherChannel is chosen. The port setup includes a mask which indicates which values the port accepts for transmission. With the maximum number of ports in a single EtherChannel, which is eight ports, each port accepts only one value. If you have four ports in the EtherChannel, each port accepts two values, and so forth.In the hypothesis of real random hash algorithm, 2, 4 or 8 ports configurations lead to fair load-balancing.

Hope to Help !!

Ganesh.H

[s.kanth]

Thanks Ganesh and Marshall for your breif explanation :-)