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Need help with lldp create neighbor messages

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SilverFox51
Occasional Visitor

Need help with lldp create neighbor messages

I am getting the following sequence of log entries from a variety of interfaces on my 5120 switch stack:

 

%Jun 15 16:04:32:241 2015 NDUO9SWMDFA1 IFNET/3/LINK_UPDOWN: GigabitEthernet2/0/16 link status is DOWN.
%Jun 15 16:05:45:522 2015 NDUO9SWMDFA1 IFNET/3/LINK_UPDOWN: GigabitEthernet2/0/16 link status is UP.
%Jun 15 16:05:45:552 2015 NDUO9SWMDFA1 MSTP/6/MSTP_FORWARDING: -Slot=2; VLAN 102's port GigabitEthernet2/0/16 has been set to forwarding state.
%Jun 15 16:05:45:554 2015 NDUO9SWMDFA1 MSTP/6/MSTP_FORWARDING: -Slot=2; VLAN 610's port GigabitEthernet2/0/16 has been set to forwarding state.
%Jun 15 16:05:58:182 2015 NDUO9SWMDFA1 LLDP/6/LLDP_CREATE_NEIGHBOR: -Slot=2; New neighbor created on Port GigabitEthernet2/0/16 (IfIndex 17825807), Chassis ID is 0050-b615-0d8f, Port ID is 0050-b615-0d8f.

 

We have had occasional problems with the attached Layer 3 failing due to what appears to be broadcast storms.  I suspect these are related.  I believe I understand to some extent what the forwarding messages mean but not the LLDP CREATE NEIGHBOR message.  Any help would be appreciated.

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Emil_Gogushev
Trusted Contributor
Solution

Re: Need help with lldp create neighbor messages

Hello,

 

LLDP means Link Layer Discovery Protocol. You can read more about it here.

https://en.wikipedia.org/wiki/Link_Layer_Discovery_Protocol

 

If you are familiar with CDP (Cisco Discovery Protocal) then it does the same thing but it is vendor-neutral and standard based.

 

%Jun 15 16:05:58:182 2015 NDUO9SWMDFA1 LLDP/6/LLDP_CREATE_NEIGHBOR: -Slot=2; New neighbor created on Port GigabitEthernet2/0/16 (IfIndex 17825807), Chassis ID is 0050-b615-0d8f, Port ID is 0050-b615-0d8f

 

So this message should basically mean that the switch has discovered a neighbor on port GigabitEthernet2/0/16. This is a device that also supports LLDP and sends LLDP DU containing information about it. You can review this information with the command display lldp neighbor-information.

You can find more information about LLDP here, page 187

 

http://h20566.www2.hp.com/hpsc/doc/public/display?sp4ts.oid=4174705&docId=emr_na-c03996931&docLocale=en_US

 

So a more accurate information would be that the switch received a LLDP DU from a device on port Gi 2/0/16. Based on this packet it created an entry in the LLDP Neighbor table. I guess that the entry in the table is deleted every time the port goes down, so we will see a new message of this type every time the port goes down and up.

 

Not sure whether this helps much but at least it sould clarify what LLDP is.

Emil /HPN
SilverFox51
Occasional Visitor

Re: Need help with lldp create neighbor messages

Thanks.  I'll do the suggested reading and see if this is a feature we even need.  And I understand what causes these now so that is a BIG help.

 

I appreciate the indepth reply, Emil.

 

Steve