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New Member

ethernchannel 3548XL-2900XL

Hi all

I have a 2 offices

the distance between this offices are 2Miles

so i had run the Fiber cable

and terminated with media converter (MC)

from fiber to Ethernet

now my network diagram looks like below



for etherchannel, i have connected to ports

made them port group,

and when i try to off one link the link is not shifting to other link..

and i made the fiber link on, then traffic going to the same link

why my traffic is not shifting to other link

when i tested in my lab near by with out media converter, the failover taking place same setup.

when i move to other buliding its not happening, dynamically..

one observation of mine, is

when otherside fiber down

still this side ethernet showing up

same case viseversa..

can some one help to sort this problem

is there any mechanism to find fiber problem and shift the link to other link

thanks in advance


New Member

Re: ethernchannel 3548XL-2900XL

If I'm reading your diagram correctly it sounds like you are going from copper to fiber and back to fiber using a media converter.

What you are probably seeing is that the connection between the switch and the media converter defines whether or not the port is up, and not the end-to-end link. Since the media converter is physically connecting to the Ethernet interface and converting the electrical signal to an optical one, the media converter is terminating point of the physical Ethernet connection and not the switch on the other side.

When you shut down a port on the switch, it most likely does not affect the connectivity of the fiber connection between the media converters or the connection between the media converter and the other switch. Another way to look at the media converter is like a hub or repeater.

If you had this connection:


and you shut down the connection between switch 1 and hub 1, the switch 2 – hub 2 connection would still be up and so would the hub 1 hub 2 connection.

Etherchannel on the 3500XL relies on the physical failure of a link to move the traffic, if the link is up and in the channel, it will be used so if you fail the port on one side, it may not affect the other side. What you need a mechanism to convince the port on switch 2 to fail its connection because it is no longer seeing switch 1. A possible solution would be enabling UDLD on both switches.

New Member

Re: ethernchannel 3548XL-2900XL


thanks for the reply

that was nice docs, i was reading and i got the meaning of the udld.

when i deployed on both the switches


interface fe0/3

udld enable

interface fe0/4

udld enable


interface fe0/20

udld enable

interface fe0/21

udld enable

iam able to see show udld fa 0/3 and 0/4

it showing otherside of the switch port and switch name

so when i go for testing,

now the traffic on 3548XL(0/3)-2924XL(0/21)

when i switch off this connection it should move the traffic to 3548XL(0/4)-2924XL(0/20)

but iam getting requested time outs

even i waited more than 15min, but no results

could you just guide me any other method, i can fix my problem

thanks for the help in advance

New Member

Re: ethernchannel 3548XL-2900XL

Hi Experts

does any one have answer for this question

or is this not possible with the Cisco Switches

if no answer means, i belive it will not support

let us come Cisco Expert coments on this question so

we will see some other solution to build