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Cisco 7401ASR Installation and Configuration Guide
OL-5419-01 B0
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-type interface
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-type interface 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-45 and 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-type command 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-config
output).
