Hello guys,
I wasn't quite sure where to start that topic, but decided to drop it here as I found this specific related to Nexus 7000.
Right, so the scenario is as follow:
[N7K-1-1]------[N7K-2-1]
| \ / |
| / \ |
| / \ |
[N7K-1-2]------[N7K-2-2]
These links are all physical, doubled, port-channel links, terminated on M2XL module.
Native vlan I've been using in Core is 3967, and it does traverse tagged (vlan dot1Q tag native in global config).
For some reason, I am unable to get two cdp neighborship between N7K-1-1 and N7K1-2 (which are both on same physical chassis but in different vDCs). Everything else works just fine (L2/L3). I have L3 OSPF adjacency working just fine there.
N7K1-1 can see N7K2-1 & 2 with absolutely the same configuration. The configuration I've got is as follow:
!
vlan dot1Q tag native
!
vlan 3967
name native_3967
!
interface port-channel3
description Po3-N7K-1-1-N7K-1-2-Po3
switchport
switchport mode trunk
switchport trunk native vlan 3967
switchport trunk allowed vlan 202,3967
logging event port link-status
logging event port trunk-status
!
#show port-channel summary interface po3 | egrep ^3
3 Po3(SU) Eth LACP Eth6/3(P) Eth6/4(P)
interface Ethernet6/3
description Po3-N7K-1-1-N7K-1-2-Eth6/3
switchport
switchport mode trunk
switchport trunk native vlan 3967
switchport trunk allowed vlan 202,3967
channel-group 3 mode active
no shutdown
The configuration is 1:1 on the otherside.
Now, the interesting part, absolutely the same configuration, applied on links to N7K1-1/1-2 - works just fine. CDP traverses and everything is good..I found, empirically, that if I add vlan 1 to the trunk - CDP pops-up...
What do I miss...?
Here are some more additional snippets, which might help:
Ethernet6/3 is up
CDP enabled on interface
Refresh time is 60 seconds
Hold time is 180 seconds
!
# show int eth 6/3 switchport
Name: Ethernet6/3
Switchport: Enabled
Switchport Monitor: Not enabled
Operational Mode: trunk
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 3967 (native_3967)
Trunking VLANs Allowed: 202,3967
FabricPath Topology List Allowed: 0
Administrative private-vlan primary host-association: none
Administrative private-vlan secondary host-association: none
Administrative private-vlan primary mapping: none
Administrative private-vlan secondary mapping: none
Administrative private-vlan trunk native VLAN: none
Administrative private-vlan trunk encapsulation: dot1q
Administrative private-vlan trunk normal VLANs: none
Administrative private-vlan trunk private VLANs: none
Operational private-vlan: none
!
# show int po3 switchport
Name: port-channel3
Switchport: Enabled
Switchport Monitor: Not enabled
Operational Mode: trunk
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 3967 (native_3967)
Trunking VLANs Allowed: 202,3967
FabricPath Topology List Allowed: 0
Administrative private-vlan primary host-association: none
Administrative private-vlan secondary host-association: none
Administrative private-vlan primary mapping: none
Administrative private-vlan secondary mapping: none
Administrative private-vlan trunk native VLAN: none
Administrative private-vlan trunk encapsulation: dot1q
Administrative private-vlan trunk normal VLANs: none
Administrative private-vlan trunk private VLANs: none
Operational private-vlan: none
# show cdp neighbors interface ethernet 6/3 - 4
Note: CDP Neighbor entry not found
# show cdp neighbors interface ethernet 6/1 - 2
Device-ID Local Intrfce Hldtme Capability Platform Port ID
N7K2-1 Eth6/1 139 R S I s N7K-C7009 Eth6/1
N7K2-1 Eth6/2 139 R S I s N7K-C7009 Eth6/2
interface Ethernet6/1
switchport
switchport mode trunk
switchport trunk native vlan 3967
switchport trunk allowed vlan 2-3967
channel-group 1 mode active
no shutdown
# show int eth 6/1 switchport
Name: Ethernet6/1
Switchport: Enabled
Switchport Monitor: Not enabled
Operational Mode: trunk
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 3967 (native_3967)
Trunking VLANs Allowed: 2-3967
FabricPath Topology List Allowed: 0
Administrative private-vlan primary host-association: none
Administrative private-vlan secondary host-association: none
Administrative private-vlan primary mapping: none
Administrative private-vlan secondary mapping: none
Administrative private-vlan trunk native VLAN: none
Administrative private-vlan trunk encapsulation: dot1q
Administrative private-vlan trunk normal VLANs: none
Administrative private-vlan trunk private VLANs: none
Operational private-vlan: none
# show run int po1
interface port-channel1
description Po1-esmdrrv1-esmdrrv2-Po1
switchport
switchport mode trunk
switchport trunk native vlan 3967
switchport trunk allowed vlan 2-3967
logging event port link-status
logging event port trunk-status
