Cisco Systems 7401ASR manual Example, Following speed/duplex settings are supported

Chapter 3 Starting and Configuring

Configuring a Cisco 7401ASR Router

Configuring the Native Gigabit Ethernet and Fast Ethernet/Ethernet Interfaces

The Cisco 7401ASR router reports both the Fast Ethernet/Ethernet and the Gigabit Ethernet ports as GE 0/0 and GE 0/1. Before configuring either port type, you must first use the media-typeinterface command to select the media type, either Gigabit Ethernet (gbic) or Fast Ethernet/Ethernet (rj45).

Changing the Media Type

Step 1 To be able to use a particular media port, use Cisco IOS to select the media type. This is done by using the media-typeinterface command:

media-type { gbic rj45 }

Example:

interface GigabitEthernet 0/0

media-type rj45

end

Step 2 After changing the media type, configure the speed and duplex to appropriately match the new interface characteristics. Changing the speed and duplex of a Cisco 7401ASR router Gigabit Ethernet interface is done using the speed and duplex interface commands.

Note These commands are only applicable when using the RJ-45 media.

speed { 10 100 1000 auto }

duplex { full half auto }

The following speed/duplex settings are supported:

Media Type	Speed	Duplex
------------------------------------------------------
RJ45	10, 100, auto	full, half, auto
GBIC	ignored (1000)	ignored (full)	(By default on this interface)

-------------------------------------------------------

When using the GBIC media, there is also the additional negotiation auto command that is used to enable the IEEE 801.1z Gigabit Ethernet (1000 Mbps) autonegotiation protocol.

Step 3 To turn this autonegotiation feature off (it is on by default), issue the interface command no negotiation auto. This is useful for connecting to other Gigabit Ethernet equipment that does not support 802.1z autonegotiation.

Note The negotiation auto feature is not supported when using the media type rj-45and will be ignored if implementation is attempted.

If you change from the gbic to rj-45 media, you must set speed and duplex after you have executed the media-typecommand to ensure the interface will operate in the correct mode.

The media type GBIC mode will always default to 1000-Mbps, full-duplex operation as this is the only configuration that is supported in this mode. Any speed or duplex commands are ignored while using this media type, even if it is present in the configuration (for example, in the show running-configoutput).

	Cisco 7401ASR Installation and Configuration Guide
OL-5419-01 B0		3-15