ProCurve Series 2300 and 2500 Switches Release Notes

196
Enhancements in Release F.02.02
CDP
3. If 1 and 2 do not apply, then the switch determines which VLANs on the neighbor’s port have IP
addresses and uses the IP address of the VLAN with the lowest VID (VLAN Identification
number) in this group.
4. If a CDP switch does not detect an IP address on the connecting port of a CDP neighbor, then
the loopback IP address is used (127.0.0.1).
For example, in figure 94, port 1 on CDP switch "X" is connected to port 5 on CDP neighbor switch
"Y", with the indicated VLAN configuration on port 5:
Figure 94. 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 Informa-
tion 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 191,
you can list a subset of data for each CDP device currently found in the switch’s CDP Neighbors table.
Table 16, "CDP Neighbors Data", describes the CDP Neighbor data set available in the Series 2500
switches.
Switch "X"
CDP Enabled on Port 1
CDP Neighbor Table
Port | Data
------|------------------
1 | 10.28.227.103
Switch "Y"
CDP Enabled on Port 5
CDP Neighbor Table
Port | Data
------|------------------
5 | Switch "X" data
Port 1
Port 5
VLAN Membership in Port 5 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 1 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.