Auto Negotiation on 3800 router Gig Interface

[nadeem-akhtar]

I can turn off auto negotiation on a fiber/Gig interface on a 3825 router by the command:

no negotiation auto

What does this buy me as in any case it will be full / 1000? What kind of (negotiation) traffic should I see with negotiation turned on on the router?

I'm troubleshooting an issue where the link between a 3825 router and a 6509 switch works fine with negotiation on on router and turned off on switch. When I put an IPS in line between the router and switch, link fails. IPS is configured with negotiation off.

Thanks

[Calin C.]

Just an idea, did you tried to hardcode the duplex and speed on both ends (3800 and IPS)

to see if like this is working.

Sometimes I had problems with auto negotiation without any other solution that configuring speed and duplex manually.