How to connect a 2950 and 5509 switches

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Oct 11th, 2002
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I have to connect this two switches, the 2950 have a GBIC module, and the 5509 a 100 FX one. When I connect them, the link on 5509 turns on, but not on 2950. I know that the GBIC port is configured as 1000 (auto), but I cant change that configuration. What should I do?

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steve.barlow Fri, 10/11/2002 - 09:54
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Disabling auto-negotation hides link drops or physical layer problems. Disabling auto-negotation is only required if end-devices such as Gigabit NICs are used. Do not disable auto-negotation between switches unless absolutely required to do so, as physical layer problems may be undetected, resulting in STP loops. Make sure both ends (ie the 2950) are auto-neg., if not one end will report up and the other down.

Are the ports trunking? If so, make sure they have the same native vlan.

This link may help:


You cannot use a GBIC to connect to a 100baseFX connector. The optics do not permit you to communicate between them. If you have to use fiber, and you cannot get a gig module for the 5509 or a new access layer switch, then you can make use of a media converter to connect to one of the 10/100 ports on the 2950.



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