Cisco Systems CISCO7201 manual Debugging

Chapter 3 Starting and Configuring the Router

Configuring a Cisco 7201 Router

When using the sfp media type, there is also the additional negotiation auto command that is used to enable the IEEE 802.1z Gigabit Ethernet (1000 Mbps) autonegotiation protocol.

To turn this negotiation auto 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 IEEE 802.1z autonegotiation. We recommend that a fixed speed and duplex setting should be used.

When the interface is configured for negotiation auto, the interface advertises all modes of which it is capable. The link only comes up if the negotiation process succeeds in finding a common mode between the Cisco 7201 SFP media type and its link partner.

The sfp media type always defaults to 1000-Mbps, full-duplex operation. The only available speed in this mode is 1000 Mbps; there is no difference whether 1000 or auto is selected. GE 0/0, GE 0/1 and GE 0/2 support half and full duplex mode; GE 0/3 only supports full duplex mode.

Note Copper SFP modules are considered to be SFP media types, not RJ-45 media types. GE 0/2 and GE 0/3 are optical ports, whether or not a copper SFP module with an RJ-45 connector, or a standard SFP module is installed.

Note The negotiation auto feature is not supported when using the rj-45ignored if implementation is attempted. (Autonegotiation is always

media type and will be on in RJ-45 mode.)

When an RJ-45 interface is enabled, it advertises all modes of which it is capable. The link only comes up if the negotiation process succeeds in finding a common mode between the Cisco 7201 RJ-45 media type and its link partner.

If you change from the sfp to the rj-45media type, you must set speed and duplex after you have executed the media type command to ensure the interface operates in the correct mode.

For information on flow control, see the “Gigabit Ethernet Flow Control Information” section on page A-9.

Debugging

Cisco IOS provides two commands to provide information on your interfaces: show interface GigabitEthernet 0/X (where X is 0, 1, 2, or 3) and show controllers GigabitEthernet 0/X (where X is 0, 1, 2, or 3).

The output of the show interface command is useful for determining the current operating mode of the interface (speed/duplex/media type) and the current interface statistics.

The output of the show controllers command displays more information specific to the Cisco 7201 router Gigabit Ethernet interface. For example, it shows the detected link status, speed, and duplex, and also determines the current status of autonegotiation and the link partners’ abilities (if it is an autonegotiation-capable interface).

The show controllers command also displays the current operating state of the driver and the Ethernet controller hardware. The show controllers command is a very powerful debugging aid, especially for Cisco engineers should you need help in debugging a problem. If you have any problems with your Gigabit Ethernet interfaces, you will need to provide this information to Cisco for analysis.

	Cisco 7201 Installation and Configuration Guide
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