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August 2005 Page 11 Dell Enterprise Product Group
Cat_6509(enable) show running-config
Link aggregation with Cisco Fast Ethernet Switches
Some customers have an investment in a Cisco Fast Ethernet (100Mbps) network. In this case the
customer may not want to incur the expense to replace their Cisco Fast Ethernet switches to match
the highest speed of the Dell PowerConnect 5316M, but they still want to have the most bandwidth
possible. Since the Dell PowerConnect 5316M supports auto-negotiation, there is nothing
additional that a customer has to do to connect aggregated links to a Cisco Fast Ethernet switch if
the Cisco switch’s link aggregation ports are also set to auto negotiation.
The ports in a Dell PowerConnect 5316M LAG are set to auto-negotiation by default. If the
negotiation setting of the LAG has been changed due to a previous configuration of the switch, use
the following command to set the LAG ports back to auto-negotiation:
5316M(config)# interface port-channel 1
5316M(config-if)# negotiation
To set the ports on a Cisco IOS switch to auto-negotiation, use the following commands:
2950(config)# interface range FastEthernet 0/1 - 3
2950(config-if)# speed auto
2950(config-if)# duplex auto
To set the ports on a Cisco CatOS switch to auto-negotiation, use the following command:
Cat_6509> (enable) set port speed 2/9-11 auto
If auto negotiation cannot be used, both the Dell PowerConnect LAG and the Cisco switch ports in
the LAG must be set to the same speed and duplex. One switch cannot be left in auto-negotiation
mode and the other forced to a certain speed and duplex or intermittent link failures may occur.
The Dell PowerConnect 5316M LAG can be forced to 100 Mbps with the following commands.
5316M(config)# interface port-channel 1
5316M(config-if)# no negotiation
5316M(config-if)# speed 100
In the example the LAG is referred to as “port-channel 1”. “no negotiation” means that there is no
auto negotiation on the ports in the LAG. “speed 100” sets all the ports in the LAG to 100Mbps.
Since this is a LAG configuration, and the 802.3ad standard requires all ports in a LAG to be full
duplex, it is not required (or allowed via the PowerConnect 5316M CLI) to set the duplex to full.
Duplex is set to full by default on LAG ports.