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sh cdp neigh - info

Posted on 2008-06-26
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Last Modified: 2008-12-24
Hello guys, i'm having some doubts that maybe you guys can help me:

magine 2 cisco devices, lets say a 6500 (on the left side) and a 2950 (on the right side)

From the left side we have 2 connections to the right side (Gi4/28 and Gi3/28)
If i make for example a "sh cdp neighbors gigabitEthernet 3/28 detail", i get:

Device ID: li02
Entry address(es):
  IP address: 10.251.0.21
  IP address: 10.251.0.20
Platform: cisco WS-C2950T-24,  Capabilities: Switch IGMP
Interface: GigabitEthernet3/28,  Port ID (outgoing port): GigabitEthernet0/1
Holdtime : 126 sec
.
.
.

If i issue the same command for the Gi4/28 i get the same thing but the outgoing por will be GigabitEthernet0/2

---------------------
The first thing i don't understand is why does it appear 2 IP addresses:
IP address: 10.251.0.21
IP address: 10.251.0.20

by the draw the 10.251.0.21 is the one connected.
-----------------------------------------------------

Now if i go the the 2950 (the right side) trought the IP 10.251.0.21 and i issue the
"sh cdp neighbors gigabitEthernet 0/1 detail" or gi0/2 i get:

Device ID: 6506-0
Entry address(es):
  IP address: 172.16.4.1
Platform: cisco WS-C6506,  Capabilities: Router Switch IGMP
Interface: GigabitEthernet0/1,  Port ID (outgoing port): GigabitEthernet3/28
Holdtime : 129 sec

which i dont understand, since the ip address i get, 172.16.4.1 is from Vlan104.


Why do i get this ip when making the sh cdp neig details for por gi0/1 and 2?
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Question by:spokoo
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5 Comments
 
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Accepted Solution

by:
ravisimpi earned 500 total points
ID: 21873727
GigabitEthernet3/28 must be associated to  Vlan-104 on the other router.

As Gig 3/48 is a layer-2 interface, sh cdp  nei will show the IP address of the vlan for which the interface is associated with.
0
 
LVL 3

Expert Comment

by:nrpanchal
ID: 21881241
Dear Author,

Is VLAN 104 is your management VLAN? Are these ports member of some vlan. Detailed configuration will give better picture.

nayan
0
 

Author Comment

by:spokoo
ID: 21881899
Hello All!

The Vlan 104 is configured in the following way:

interface Vlan104
 ip address 172.16.4.1 255.255.255.0


and the for example, the interface gi3/28:

interface GigabitEthernet3/28
 no ip address
 switchport
 switchport access vlan 10
 switchport mode trunk
 switchport nonegotiate
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Expert Comment

by:ravisimpi
ID: 21923982
The asker has requested for

Why do i get this ip when making the sh cdp neig details for por gi0/1 and 2?

Answer provided is

GigabitEthernet3/28 must be associated to  Vlan-104 on the other router.

As Gig 3/48 is a layer-2 interface, sh cdp  nei will show the IP address of the vlan for which the interface is associated with.

He can tell why he won't accept the answer. Is there anything else he wants to know apart from where the IP address is being fetched?
0
 

Expert Comment

by:Mohil
ID: 23242269
What rubbish answer is this ...
0

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