Local-Area Networks and LAN Switching - CCIE Routing and Switching Exam Certification Guide - page 158

Example 4-18 Router show cdp Command Output

R8#show cdp ?
entry Information for specific neighbor entry
interface CDP interface status and configuration
neighbors CDP neighbor entries
traffic CDP statistics
| Output modifiers
<cr>

To find out about neighboring Cisco routers or switches, use the show cdp neighbors com-
mand, which gives summary information of each router. Example 4-19 shows the output of the
show cdp neighbors command. The router has two neighbors, called R7 and R9, which are
Cisco 2500 routers.

Example 4-19 Router show cdp neighbors Command Output

R8#show cdp neighbors
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater

Device ID Device ID Local Intrfce Holdtme Capability Platform Port ID

R7 Ser 1 133 R 2500 Ser 1
R9 Tok 0 176 R 2500 Tok 0

Platform

R7 2500

R9 2500

You use the same command on a Catalyst switch. Example 4-20 shows the output of the show
cdp neighbor command of a switch. This switch has six neighboring routers (one MC3810 and
five Cisco 2500s), which are marked with an R that describes router capabilities.

Example 4-20 Switch show cdp neighbor Command Output

cat5000: (enable) show cdp neighbor
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater

Port Device-ID Port-ID Platform Capability
-------- ----------------------- ----------------- ------------------ --
2/4 R3 Ethernet0 Cisco MC3810 R
2/5 R5 Ethernet0 cisco 2500 R
2/7 R7 Ethernet0 cisco 2500 R
2/9 R9 Ethernet0 cisco 2500 R
2/10 R10 Ethernet0 cisco 2500 R
2/11 R6 Ethernet0 cisco 2500 R

Platform Capability

To get more detailed information about neighboring routers, use the show cdp neighbors detail
command, as shown in Example 4-21. From the output, you can gather neighbor information
such as name, IP address, platform type, and IOS version.