When i enter this command i get my neighbors with some IPs and these are not their Telnet IPs. Can you tell me where those IP belong to ?
sh cdp entry * protocol
Network Engineering Stack Exchange is a question and answer site for network engineers. It only takes a minute to sign up.Sign up to join this community
According to the prefix name "RTR_" those devices are routers.
Routers generally have several IP addresses, so CDP may display only one of those IP addresses. (Well, even layer 2 switches can have several IP addresses.)
From this post by MAG03 on Experts-Exchange.com, which is consistent with what I see right now one some switches, it seems that:
CDP determines the IP address to use by first looking at the directly connected interface and seeing if there is an IP address on it. If there is, that IP address will be used. If the link is a trunk CDP will choose the lowest IP address of the vlan interfaces as the IP address it will use to describe the neighbor.
so if SW1 has vlans with IP 126.96.36.199 and another vlan with ip 188.8.131.52, SW2 has vlans with IP addresses of 184.108.40.206 and 220.127.116.11, and the link connecting the two is a trunk.
Given that CDP is enabled on the trunk interface SW1 will be shown as having an address of 18.104.22.168 and SW2 will have an addess of 22.214.171.124 in the show cdp neighbor detail output.
Usually the IP used to manage a device is the loopback IP and so is never directly connected to a CDP neighbor and is unlikely to be shown in your CDP command
However if you issue the
show cdp neighbors detailcommand you will see this IP address.