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12-25
Configuring for Network Management Applications
CDP
Monitoring and Managing
the Switch
Figure 12-15. Example of IP Address Selection when the CDP Neighbor Has Multiple VLANs with IP
Addresses
CDP Neighbor Data and MIB Objects
The switch places the data received from inbound CDP packets into its MIB
(Management Information Base). This data is available in three ways:
■ Using the switch’s show cdp neighbors command to display a subset of
Neighbor data
■ Using the walkmib command to display a listing of the CDP MIB objects
■ Electronically, using an SNMP utility designed to search the MIB for
CDP data
As shown under “Viewing the Current Contents of the Switch’s CDP Neighbors
Table” on page 12-19, you can list a subset of data for each CDP device
currently found in the switch’s CDP Neighbors table. Table 12-2, "CDP
Neighbors Data", describes the CDP Neighbor data set available in the Switch
4108GL.
Switch "X"
CDP Enabled on Port A1
CDP Neighbor Table
Port | Data
------|------------------
A1 | 10.28.227.103
Switch "Y"
CDP Enabled on Port C5
CDP Neighbor Table
Port | Data
------|------------------
C5 | Switch "X" data
Port A1
Port C5
VLAN Membership in Port C5 of Switch "Y" VID IP Address?
DEFAULT_VLAN (Primary VLAN) 1 No
Blue_VLAN 200 10.28.227.103
Red VLAN 300 10.28.227.88
Thus, CDP switch "X" detects CDP switch "Y" on port A1 and shows 10.28.227.103 in its CDP table entry because in CDP switch "Y" the
Primary VLAN does not have an IP address and the Blue_VLAN has a lower VID than the Red_VLAN.