2950 G-12 ports how to open port in loop

Unanswered Question
May 23rd, 2007

I have 3 Switch 12 ports, connected each other in looping and i want to add another loop so that in case the cable is dead i have another backup, what is the command or settings to make the state of some ports are always forward, i need someone kind here to support me plss!

I have this problem too.
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Amit Singh Wed, 05/23/2007 - 23:19

I hope that I am correcct in your present setup.In your design, Switch 1 is connected to switch 2, then switch2 is connected to switch 3 and switch3 is connected bacl to switch1 to form a loop.

Where do you want to connect another cable? If you want to create another cable between switch 3 and switch1, i would suggest to create an ether-channel of the two ports. This will give you redundancy, load-sharing and an alternate oath in case one of the link goes down.According to the STP it will be a single logical link and both of the ports will be forwarding incase if its not already blocked. If its in block state then we can use " spanning-tree port priority " or "spanning-tree vlancost" command to make this a forwrading link.

HTH,Please rate if it does.

-amit singh

chacktaylor Wed, 05/23/2007 - 23:32

i tried to do that in ether channel on group 1 mode on, but the switch 3 it goes shutting down on all ports, anyway that exacly the scenario i have now here! and im realy, realy glad your support plss, i need another help in this case

Amit Singh Thu, 05/24/2007 - 00:03

You have to make sure that you have same configurations applied on the ports which you are bundelling in an ether-channel group. Configs like trunk config, STP config, Speed/duplex configs have to be exactly same on all the ports in an ether-channel config.

Please see that link below and it will come handy.


HTH,Please rate of ot does.

mahmoud.hattab Thu, 05/24/2007 - 00:17

I did try this configuration. But I have a total of 12 Ports that need to group, as far as i know, each channel-group is only allowed of 8 physical port to join, I can create another channel-group like group 2, but how I can combine group 1 and group 2 as one logical port, so that even I remove all the connection and leave only 1 link from S1 to S3 to S2, I can still ping the HostB(S2) from HostA(S1) without a timeout. Thanks

mahmoud.hattab Thu, 05/24/2007 - 00:02

Good day, I will tell you the exact configuration of this scenario. I have 3 Cisco Switches 2950G-12-EI. S1/P1 connected to HostA, S1/P2 to S2/P2, S1/P3 to S3/P3, S3/P4 to S2/P4, S2/P1 to HostB. I want another redundant looping, which is S1/P5 to S2/P5, S1/P6 to S3/P6, S3/P7 to S2/P7. While im pinging from HostA to HostB then I shutdown all the connections of S1 to S2, including the one connection from S1 to S2 and S2 to S3, I will not encounter a timeout. I did try this succesfully using a 2 Switches 2950G-12-EI, connected with a redundant cable. I used a command of #channel-group 1 mode on the 4 ports of S1 and S2, then I did not encounter a timeout. But when I applied this channel-group using 3 Switches scenario, the S3 switches is shutting down. Im aware the each group are only allowed of eight physical group on each channel-group. Please let me know if you have other idea if how I can solve this. Thank you very much and I will wait for your reply, Nes of Riyadh, Saudi Oger.


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