Configuring for Network Management Applications

CDP

and “E” are not neighbors because the intervening CDP-disabled switch “D” does not forward CDP packets; i.e. is not transparent to CDP traffic. (For the same reason, switch “E” does not have any CDP neighbors.)

CDP Switch "A"

Port A1

(CDP Running)

 

CDP Neighbor Table

 

Port Data

 

---------------------------

 

A1

Host 1 data

Port A2

A1

Host 2 data

 

A1

Host 3 data

 

A2

Switch "B" data

 

CDP Switch "B"

Port B1

(CDP Running)

CDP Neighbor Table

 

Port

Data

Port B5

Non-CDP Device "X"

Such as a Non-CDP

Hub or Switch

Non-CDP Device "Y"

Such as a Non-CDP

Hub or Switch

Port D3

CDP Workstation "1" (Host 1)

(CDP Running)

CDP Workstation "2" (Host 2)

(CDP Running)

CDP Workstation "3" (Host 3)

(CDP Running)

-------

--------------------

 

B1

Switch "A" data

 

B7

Switch "C" data

 

No CDP data for Switch

 

"D" because it has dis­

 

Port B7

abled CDP operation.

 

CDP Switch "C"

(CDP Running)

Port C3

CDP Neighbor Table

Port

Data

-------

--------------------

C3

Switch "B" data

CDP-Disabled Switch "D"

(No CDP Neighbor Table)

This switch drops CDP packets.

Port D17

"A", "1", "2", and "3" are CDP neighbors. "A" and "B" are CDP neighbors.

"B" and "C" are CDP neighbors.

Because "D" is CDP-capable, but has disabled CDP, it is not a CDP neighbor to either "B" or "E".

CDP Switch "E"

(CDP Running)

CDP Neighbor Table

Empty-No CDP

Neighbors

Port E1

Figure 13-12. Example of Incoming CDP Packet Results

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