Hi,
I have a problem where a 4500X switch is not receiving CDP from all the interconnects C3850 switches. The network is strictly a star with the 4500X forming the core, and the 3850s the access layer. This part of the network is purely Layer 2 with VLANs and management is in-band through vlan 1100.
The 4500X is running 3.6.4E while the 3850s are running 3.7.1E.
The access 3850s are receiving and displaying CDP from the core switch and other connected devices (mostly access points and phones), but the problem is the 4500X is showing nothing:
core-4500#show cdp neighbors
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone,
D - Remote, C - CVTA, M - Two-port Mac Relay
Device ID Local Intrfce Holdtme Capability Platform Port ID
Total cdp entries displayed : 0
core-4500# show cdp
Global CDP information:
Sending CDP packets every 60 seconds
Sending a holdtime value of 180 seconds
Sending CDPv2 advertisements is enabled
core-4500#show cdp traffic
CDP counters :
Total packets output: 4963, Input: 0
Hdr syntax: 0, Chksum error: 0, Encaps failed: 0
No memory: 0, Invalid packet: 0,
CDP version 1 advertisements output: 0, Input: 0
CDP version 2 advertisements output: 4963, Input: 0
... and on the access switches:
access-3850#show cdp neighbors
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone,
D - Remote, C - CVTA, M - Two-port Mac Relay
Device ID Local Intrfce Holdtme Capability Platform Port ID
core-4500.dcn Ten 1/1/3 171 R S I WS-C4500X Ten 1/31
... lots of other devices...
access-3850#show cdp traffic
CDP counters :
Total packets output: 327660, Input: 128461
Hdr syntax: 0, Chksum error: 0, Encaps failed: 0
No memory: 0, Invalid packet: 0,
CDP version 1 advertisements output: 0, Input: 0
CDP version 2 advertisements output: 327660, Input: 128461
I suspect the problem has something to do with tagging of the CDP packets, and nothing being exposed to receive them, but it is unclear to me how I resolve this problem in this otherwise pure Layer 2 fabric.
I've included below a precis of the 4500X configuration. Any tips on how to get CDP showing the access switches would be appreciated.
Thanks,
Daniel
!
version 15.2
!
boot-start-marker
boot system flash bootflash:cat4500e-universalk9.SPA.03.06.04.E.152-2.E4.bin
boot-end-marker
!
!
vrf definition mgmtVrf
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address-family ipv4
exit-address-family
!
address-family ipv6
exit-address-family
!
!
spanning-tree mode pvst
spanning-tree extend system-id
spanning-tree vlan 1-4094 priority 8192
!
vlan internal allocation policy ascending
!
vlan 2-1001,1006-4094
!
interface FastEthernet1
vrf forwarding mgmtVrf
no ip address
speed auto
duplex auto
!
interface TenGigabitEthernet1/1
switchport mode trunk
mtu 9198
!
!
interface TenGigabitEthernet1/32
switchport mode trunk
mtu 9198
!
!
interface TenGigabitEthernet2/1
switchport mode trunk
mtu 9198
!
!
interface TenGigabitEthernet2/8
switchport mode trunk
mtu 9198
!
interface Vlan1
description - not used -
no ip address
shutdown
!
interface Vlan1100
ip address 10.11.0.1 255.255.255.0
!
