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Port speeds

My core port speed is set to a-100 and a-full. The switch the  core port is connected to is set to a-1000 and a-full. I am having problems when I connect to the access layer switch.

When I change my core to 1000 speed  I can't telnet into my access switch. When I change the core back to 100 I can. Also when I telnet into my access layer switch, go into the port (int gi0/1) and type speed 100, it tells me its an unrecognized command. It won't let me change the speed.

What am I doing wrong? Do i need to use a console cable to change the speed of my access layer switch?

2 REPLIES
Cisco Employee

Re: Port speeds

I am not sure what kind of switches you are using. But, seems like you have an incompatibility between the switches. The best way to address it would be to enable auto-negotiation on both ends.

interface

speed auto

duplex auto

This will ensure that both ends exchange their capabilities and then negotiate a common speed/duplex settings. Here is a document that explains the need for autonegotiation.

http://www.dell.com/content/topics/global.aspx/power/en/ps1q01_hernan?c=us&cs=555&l=en&s=biz

Here is a document that lists the compatibility issues.

http://www.cisco.com/warp/public/473/46.pdf

Hope this helps.

Regards,

NT


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Re: Port speeds

My core port speed is set to a-100 and a-full. The switch the  core port is connected to is set to a-1000 and a-full. I am having problems when I connect to the access layer switch.

When I change my core to 1000 speed  I can't telnet into my access switch. When I change the core back to 100 I can. Also when I telnet into my access layer switch, go into the port (int gi0/1) and type speed 100, it tells me its an unrecognized command. It won't let me change the speed.

What am I doing wrong? Do i need to use a console cable to change the speed of my access layer switch?

What is the model of switch and version ? and what are you getting under interface mode when you try to configure speed along with question mark like

if)#speed ?

Hope to Help !!

Ganesh.H

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