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HP 1920 loopback problems on trunks between switches

 
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Dunky
Regular Advisor

HP 1920 loopback problems on trunks between switches

I have a number of HP 1920 switches.

The interconnects between the switches are configured with the following:

loopback-detection enable

loopback-detection control enable

loopback-detection per-vlan enable

Every so often I am getting the following in my syslog server which are both log entries and SNMP traps...
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18972672 GigabitEthernet1/0/25 in VLAN 1 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18972672 GigabitEthernet1/0/25 in VLAN 2 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18972672 GigabitEthernet1/0/25 in VLAN 5 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18972672 GigabitEthernet1/0/25 in VLAN 3 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18972672 GigabitEthernet1/0/25 in VLAN 51 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18972672 GigabitEthernet1/0/25 in VLAN 56 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18972672 GigabitEthernet1/0/25 in VLAN 55 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18972672 GigabitEthernet1/0/25 in VLAN 53 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18972672 GigabitEthernet1/0/25 in VLAN 52 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18972672 GigabitEthernet1/0/25 in VLAN 4 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18972672 GigabitEthernet1/0/25 in VLAN 59 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18972672 GigabitEthernet1/0/25 in VLAN 58 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18972672 GigabitEthernet1/0/25 in VLAN 64 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18972672 GigabitEthernet1/0/25 in VLAN 200 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18972672 GigabitEthernet1/0/25 in VLAN 65 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18972672 GigabitEthernet1/0/25 in VLAN 57 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/25 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/25 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/25 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/25 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/25 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/25 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/25 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/25 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/25 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/25 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/25 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/25 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/25 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/25 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/25 recovered.
Aug 1 10:01:52 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/25 recovered.
Aug 1 10:01:53 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18976768 GigabitEthernet1/0/26 in VLAN 51 recovered.
Aug 1 10:01:53 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18976768 GigabitEthernet1/0/26 in VLAN 3 recovered.
Aug 1 10:01:53 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18976768 GigabitEthernet1/0/26 in VLAN 52 recovered.
Aug 1 10:01:53 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18976768 GigabitEthernet1/0/26 in VLAN 56 recovered.
Aug 1 10:01:53 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18976768 GigabitEthernet1/0/26 in VLAN 55 recovered.
Aug 1 10:01:53 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18976768 GigabitEthernet1/0/26 in VLAN 2 recovered.
Aug 1 10:01:53 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18976768 GigabitEthernet1/0/26 in VLAN 53 recovered.
Aug 1 10:01:53 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18976768 GigabitEthernet1/0/26 in VLAN 4 recovered.
Aug 1 10:01:53 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18976768 GigabitEthernet1/0/26 in VLAN 1 recovered.
Aug 1 10:01:53 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18976768 GigabitEthernet1/0/26 in VLAN 5 recovered.
Aug 1 10:01:53 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18976768 GigabitEthernet1/0/26 in VLAN 63 recovered.
Aug 1 10:01:53 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18976768 GigabitEthernet1/0/26 in VLAN 64 recovered.
Aug 1 10:01:53 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/RECOVERED(t) Trap 1.3.6.1.4.1.25506.2.95.1.0.4: Loopback on the interface 18976768 GigabitEthernet1/0/26 in VLAN 57 recovered.
Aug 1 10:01:53 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/26 recovered.
Aug 1 10:01:53 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/26 recovered.
Aug 1 10:01:53 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/26 recovered.
Aug 1 10:01:53 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/26 recovered.
Aug 1 10:01:53 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/26 recovered.
Aug 1 10:01:53 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/26 recovered.
Aug 1 10:01:53 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/26 recovered.
Aug 1 10:01:53 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/26 recovered.
Aug 1 10:01:53 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/26 recovered.
Aug 1 10:01:53 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/26 recovered.
Aug 1 10:01:53 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/26 recovered.
Aug 1 10:01:53 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/26 recovered.
Aug 1 10:01:53 192.168.100.9 2016 local7 notice SWITCH-05 %%10LPDETECT/5/LPDETECT_RECOVERED(l): Loopback on GigabitEthernet1/0/26 recovered.

It is effectivly a fully meshed LAN with two ports on each switch being connetected to other switches. MSTP is all configured and working ok but we get these errors on different switches every 7-10 days and when it occurs in office hours it causes issues.

Dos anyone know what would cause these and if there is a way of preventing users losing connectivity?
Thanks

Steve

7 REPLIES
parnassus
Honored Contributor

Re: HP 1920 loopback problems on trunks between switches

Hi!

Those (LPDETECT_RECOVERED and LPDT_RECOVERED) are Comware 5 notification messages (both with Severity Level: 5 which groups notification messages for a "Normal but significant condition") related to LPDETECT (Loop Detect for Loop Condition Handling) and LPDT (Loopback Detection) modules; they state that "Loopback on the interface is eliminated" or "The loop condition on an interface was removed" (for the LPDETECT_RECOVERED) and "The loop condition on a port was removed" (for the LPDT_RECOVERED) on related interfaces/ports.

Are you referring to the scenario described on this post?

Dunky
Regular Advisor

Re: HP 1920 loopback problems on trunks between switches

Hi parnassus,

Yes that is the LAN which I have the issue on.

From what I can tell trawling thru logs, is that MSTP changed BAGG2 on SWITCH-02 to FORWDING because no BPDU's were seen on BAGG2 n SWITCH-03.  Immediatly after this I see the LPDETECT_BLOCK & LPDETECT_RECOVERED messages.

I have no idea why SWITCH-03 didnt receive BDPU's from SWITCH-00, but I think this is the cause ot the LPDETECT-BLOCK.

I am beginning to wonder whether maybe I should have loopback detection enabled on uplinks and just rely on MSTP?

parnassus
Honored Contributor

Re: HP 1920 loopback problems on trunks between switches

Probably, are your wondering to enable Loopback Detection globally on each "edge" unit (Switch 04, 05 and 06, right?) and then set Loopback Detection and Detection Control on trunk/hybrid interfaces (maybe with Detection in VLAN too)?

The more I look at your network map the more I think you've replicated a sort of "IRF Core (in a sort of ring topology with all those BAGGs that loop back to Switch 00) with a sort of (distributed?) Trunking between the Core and Edge Switches" scenario...but this was done using HPE 1920!

A real challenge!

Dunky
Regular Advisor

Re: HP 1920 loopback problems on trunks between switches

Hi,

Yes you are correct in that I have enabled Loopback Detection globally (but on EVERY switch).

I have "loopback-detection enable" on all interfaces.

In addtion, on the trunk ports, I have "loopback-detection control enable" and "loopback-detection per-vlan enable".

 

The LAN is in and working fine apart from these LPDETECT_BLOCK & LPDETECT_RECOVER errors which have an impact. I have VLAN's split across the fibre uplinks with failiver and its working a treat :)

In fact I have just discovered that I have "stp loop-protection" on g1/0/26 on both SWITCH-05 & -06.  Have just removed that as they were the only two with it and the only two that exhibit the problem (so far as I can tell by looking at logs which only go back a week or so). Will see if that makes any difference although I am not too hopeful.

Looking at the logs I have come up with the following sequence of events:

09.59.38 SWITCH-03  BAGG2 Instance 0,1,2 No BDPU received

10.00.09 SWITCH-02 BAGG2 Inst 0,1,2 detected topology change

                                     BAGG2 is set to FORWARDING Inst 0,1,2

10.00.10 SWITCH-01 BAGG2 Inst 0 detected toopolgy change

10.00.12 SWITCH-04 Int g1/025 Inst 0 detected topology change

10.00.14 SWITCH-00 BAGG1 Inst 0 detected topology change 

10.00.12 SWITCH-05 Int g1/0/25 Inst 0 Topology Change

                                    LPDETECT_BLOCK on g1/0/25 and g1/0/26 (fibres)

10.00.27 SWITCH-02 Inst 0,1,2 BAGG2 set to discard

10.01.52 SWITCH-05 LPDETECT_RECOVERED on g1/0/25 and g1/0/26

 

 

 

 

16again
Respected Contributor
Solution

Re: HP 1920 loopback problems on trunks between switches

Do not enable loopdetect on links between switches!   Use it only on access ports.
On a loop, some interface will have to enter block mode. (by design)
If inter-switch port is in the loop, loopdetection might kick in on that link, taking down ALL traffic.   Loop detection should only take down the access link causing the loop.

Dunky
Regular Advisor

Re: HP 1920 loopback problems on trunks between switches

Thanks for the reply 16again.

At present I have:

loopback-detection enable

 loopback-detection control enable

 loopback-detection per-vlan enable

on the inter-switch links, and just "loopback-detection enable" on the access links.

I will disable loopback-detection on the interswitch links. 

 

On ports where clients are connected via phones (thus trunk ports), would you just enable loop detection or have the three commands above that I currently have on the interswitch links?

 

Another query if I may, what does the "stp loop-protection" command do and do I need it anywhere?  I thought the whole purpose of STP was to prevent loops, so not quite seeing the relevance of this command.

 

TIA

Dunky
Regular Advisor

Re: HP 1920 loopback problems on trunks between switches

fyi, I have not seen any further issues sincxe disabling loopback-detection on the interswitch links.