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Dual links on the Network Topology map

Occasional Contributor

Dual links on the Network Topology map


After we update imc to version 7.3 we got dual links on the network map. ( lok at the photo i have uploaded). 

One link shows less information than the other one does.  how can i  "remove/hide" one link on the map?

we have a juniper ex4600  as core switch.  Some 2530G have  dual link other have not, We have more models than 2530G that has this problem. We can not see any connection why some have double links and others do not.  Ther is only dual links from Juniper EX4600 to the first swich. after the first shwitch ther is singel links.  ( lok at the photo i have uploaded). We have compared settings on the interface on Junipern and they are the same, so we can not find anything that can cause us to get duplicate links.


Frequent Visitor

Re: Dual links on the Network Topology map


We have same issue with 1800 series switches since 7.3

I have also create a post 3 weeks ago :

No one helped me.



Valued Contributor

Re: Dual links on the Network Topology map


Has someone found a solution for this? I run into the same issue with Moxa industrial switches connected on HPE 5130, or Moxa to connected to Moxa.

In some cases I have a single link correctly displayed, and in other cases I have a dual link displayed.

In the case of dual link, one link description is correct "SwitchA-Port1 - SwitchB-port1" and the fantom  link description is "SwitchA-Port1 - SwitchB port5" (in some cases the port5 has nothing connected to it !)

Impossible to find a relation between correct topology representation and the wrong one.

I have checked by running lldp manually on both sides, and I could not find any wrong :(

I m using IMC version E0605P06 and I did not see this issue addressed in the release notes of E0703.

Any idea on how to further proceed?






Re: Dual links on the Network Topology map


You can troubleshoot such link issues to some extent in IMC 7.3 with the Topology Diagnosis. Right-click on one of the devices in the topology and click Topology Diagnosis, it will show you which neighbor-discovery related protocols are running on the device, and which ones IMC is using.

Generally it is a good idea to use only one single neighbor discovery protocol, preferably LLDP, as it usually proves reliable. However IMC will also process CDP, STP and MAC intersections by default, and when they are all running, this can sometimes cause inconsistencies in the link calculation and "fake links". There was also a ProCurve-specific bug where CDP inconsistencies break the algorithm.

Try ensuring only LLDP is running and then synchronizing the devices in IMC.

Under System > System Configuration > System Settings > Layer 2 Topology Configuration is where you can find the settings for the topology calculation. Unless you need them, I would suggest setting STP Link Calculation, MAC Intersection and Inter-Routing Interface Calculation to "No" to prevent them from interfering with the topology (and then synchronizing devices again).

Getting a bit more advanced here, you can also get a full text dump of the topology information IMC knows via System Configuration > Data Collection > check the box for "l2topo" and run the collection, then open the l2topo.txt in a text editor. It will show you a long list of every IMC device and which link information was gathered from which protocols.

PS. There are also some vendors with poorly implemented LLDP-MIBs, so if it still doesn't work correctly, check the SNMP output from the device for that MIB to make sure the device isn't sending IMC something incorrect.

Best regards,

Working @ HPE
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