Operating instructions

216 Cisco Systems Intelligent Gigabit Ethernet Switch Module

Sending 10, 1000-byte ICMP Echos to 172.26.146.1, timeout is 1 seconds:

!!!!!!!!!!

Success rate is 100 percent (10/10), round-trip min/avg/max = 4/4/4 ms

show cdp neighbor

show cdp neighbor is a powerful troubleshooting command. At a minimum, it tells what ports

are connected on each side of a link. It can also tell the type of device on the other side of a

link, the IOS version on the other side of the link, and the IP address of the devices on the

other side of the link. (To see the IOS and IP address on the other side, you must add the

keyword detail to the end of the show cdp neighbor command.

It requires that both sides of the link be Cisco devices. (CDP is a Cisco proprietary protocol.)

Figure 8-5shows the attributes of this command.

Figure 8-5 Output of show cdp nei command

• Very important tool – Based on Cisco Discovery Protocol

• CDP is a Cisco protocol that runs between links and learns

information about the connection

• Shows connection info from CIGESM to uplinks

• Shows device name/model number, ports used, etc.

• cigesm_t#sh cdp nei

Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge

S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone

Device ID Local Intrfce Holdtme Capability Platform Port ID

c3750-24_A Gig 0/19 143 S I WS-C3750-2Fas 1/0/19

c3750-24_A Gig 0/20 143 S I WS-C3750-2Fas 1/0/20

c3750-24_A Gig 0/18 143 S I WS-C3750-2Fas 1/0/18

c3750-24_A Gig 0/17 143 S I WS-C3750-2Fas 1/0/17

cigesm_t Gig 0/15 164 S I OS-CIGESM-Gig 0/15

• Very handy to confirm cables are plugged into correct ports

• “show cdp nei detail” gives even more information on device on

the other side of the link

Device name on