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Nexus 7k LLDP neighbor output not providing IP address details

clive.hodgetts
Level 1
Level 1

Hi, 

We are looking to enable LLDP across our Nexus estate and to disable CDP. As is well known, LLDP does provide greater node information than CDP especially with regards VoIP devices. However, when we enabled LLDP on several 7k VDC's and compared information between the LLDP outputs and CDP outputs we noted that the management IP address details on the LLDP outputs were mac addresses and not IPv4 address format. My question is, is this normal output or is there something we need to configure to correct this. The output from a connected 3560 displays as expected. See the example below:

 

nexus-a# sh lldp neigh interface e1/25 detail
Capability codes:
(R) Router, (B) Bridge, (T) Telephone, (C) DOCSIS Cable Device
(W) WLAN Access Point, (P) Repeater, (S) Station, (O) Other
Device ID Local Intf Hold-time Capability Port ID

Chassis id: fc5b.3947.5d40
Port id: Eth1/25
Local Port id: Eth1/25
Port Description: *** VPC Peer-Link to nexus-a E1/25 ***
System Name: nexus-b
System Description: Cisco NX-OS(tm) n7700, Software (n7700-s2-dk9), Version 6.2(
16), RELEASE SOFTWARE Copyright (c) 2002-2013 by Cisco Systems, Inc. Compiled 1/
27/2016 9:00:00
Time remaining: 101 seconds
System Capabilities: B, R
Enabled Capabilities: B, R
Management Address: fc5b.3947.5d40
Vlan ID: 1

Total entries displayed: 1
nexus-a#

nexus-aa# sh lldp neigh interface e1/31 detail
Capability codes:
(R) Router, (B) Bridge, (T) Telephone, (C) DOCSIS Cable Device
(W) WLAN Access Point, (P) Repeater, (S) Station, (O) Other
Device ID Local Intf Hold-time Capability Port ID

Chassis id: f07f.06ab.bc80
Port id: Te1/1/4
Local Port id: Eth1/31
Port Description: *** "20Gb Link to NEXUS_A E1/46 ***
System Name: 3650-1
System Description: Cisco IOS Software [Denali], Catalyst L3 Switch Software (CA
T3K_CAA-UNIVERSALK9-M), Version 16.3.10, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2020 by Cisco Systems, Inc.
Compiled Mon 27-Jan-20 09:14 by
Time remaining: 113 seconds
System Capabilities: B, R
Enabled Capabilities: B, R
Management Address: 192.168.141.27
Vlan ID: not advertised

Total entries displayed: 1


nexus-a# sh cdp neigh detail
----------------------------------------
Device ID:nexus-b(JAF1825DDDD)
System Name: nexus-b

Interface address(es):
IPv4 Address: 10.144.169.3
Platform: N77-C7710, Capabilities: Router Switch IGMP Filtering Supports-STP-Dis
pute
Interface: Ethernet1/25, Port ID (outgoing port): Ethernet1/25
Holdtime: 172 sec

Version:
Cisco Nexus Operating System (NX-OS) Software, Version 6.2(16)

Advertisement Version: 2

Native VLAN: 1
Duplex: full
----------------------------------------

Device ID:3650-1
VTP Management Domain Name: null

Interface address(es):
IPv4 Address: 192.168.141.27
Platform: WS-C3650-48PD, Capabilities: Router Switch IGMP Filtering
Interface: Ethernet1/31, Port ID (outgoing port): TenGigabitEthernet1/1/4
Holdtime: 159 sec

Version:
Cisco IOS Software [Denali], Catalyst L3 Switch Software (CAT3K_CAA-UNIVERSALK9-
M), Version 16.3.10, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2020 by Cisco Systems, Inc.
Compiled Mon 27-Jan-20 09:14 by mcpre

Advertisement Version: 2

Native VLAN: 3
Duplex: full
Mgmt address(es):
IPv4 Address: 192.168.141.27
----------------------------------------

Although the LLDP outputs are provide better/more information without the IP addresses being displayed we would not be able to disable CDP as the network engineers are very much used to having this information to work with when troubleshooting the network. So, if this is normal behaviour then we will need to have LLDP and CDP enabled.

 

Any guidance would be appreciated!

 

Thanks,

Clive Hodgetts 

1 Accepted Solution

Accepted Solutions

The older code by default sends mac address for management IP.

The newer code defaults to v4 and v6 address.

If your code is new enough it should have the option to enable sending the management v4 and v6 like this:

 

(config)# lldp tlv-select management-address ?
<CR>
v4 Management Address TLV v4
v6 Management Address TLV v6

 

 

Which then:

# show lldp tlv-select
management-address-v4
management-address-v6
port-description
port-vlan
power-management
system-capabilities
system-description
system-name
dcbxp
DCBX Congestion Notification TLV
DCBX ETS Configuration TLV
DCBX ETS Recommendation TLV
DCBX PFC Configuration TLV
DCBX Application Priority TLV
DCBX Application VLAN TLV

View solution in original post

4 Replies 4

f00z
Level 1
Level 1

You can edit lldp TLV (the information fields it sends to neighbors)

look at "lldp tlv-select" in config mode 

There is a  "lldp tlv-select management-address"  configuration command which enables sending of the management ip in lldp.

(config)# lldp tlv-select ?
dcbxp DCBXP TLVs
management-address Management Address TLV
port-description Port Description TLV
port-vlan Port Vlan ID TLV
system-capabilities System Capabilities TLV
system-description System Description TLV
system-name System Name TLV

 

There is also a PER-PORT lldp tlv-set management address command where you can set the IP:

(config-if)# lldp tlv-set ?
management-address Management address to be sent in management-tlv of LLDPDU.
vlan VLAN-id whose SVI IP address should be used as management adrress in management-tlv of LLDPDU. Default is native VLAN.

 

 

 

Hi,

thank you for your reply. 

 

I have checked the configuration and the tlv-select for the below are enabled by default but I checked them and confirmed that the management-address is definitely enabled:

nexus-a# sh lldp tlv-select
management-address
port-description
port-vlan
system-capabilities
system-description
system-name
dcbxp
nexus-a#


With regards the interface options for LLDP:


nexus-a# conf t
Enter configuration commands, one per line. End with CNTL/Z.
nexus-a(config)# int e1/3
nexus-a(config-if)# lldp ?
receive Enable LLDP reception on interface
transmit Enable LLDP transmission on interface

There are only the above options for LLDP at the interface level.

 

My question now is whether the lldp tlv management address option isn't shown when sourced from a Nexus device (no IP just a mac address) by design or if it might be a bug?

 

Thanks again....

 

The older code by default sends mac address for management IP.

The newer code defaults to v4 and v6 address.

If your code is new enough it should have the option to enable sending the management v4 and v6 like this:

 

(config)# lldp tlv-select management-address ?
<CR>
v4 Management Address TLV v4
v6 Management Address TLV v6

 

 

Which then:

# show lldp tlv-select
management-address-v4
management-address-v6
port-description
port-vlan
power-management
system-capabilities
system-description
system-name
dcbxp
DCBX Congestion Notification TLV
DCBX ETS Configuration TLV
DCBX ETS Recommendation TLV
DCBX PFC Configuration TLV
DCBX Application Priority TLV
DCBX Application VLAN TLV

Thank you. We are currently running 6.2(16) but plan to upgrade soon to 8.4. We will complete the upgrade and check the LLDP options and outputs.

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