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Layer 2 loop issue

TPG-GVA
Occasional Advisor

Layer 2 loop issue

Hi Gurus,

 

I've attached the network topologies below.

I've 2 A10 Thunder Loadbalancer connected to my stack of switches in Active / Passive Mode.

Note that A10 Thunder doesn't support STP but forward STP packet.

In the attached configuration, if I disabled interfaces connected to the standby Loadbalancer, everything is working as expected, but as soon as the secondary device is connected I see "Potential Loop Issue".

My stack of switch has STP disabled because there is one single logical uplink port.

 

Mar 31 2015 14:35:24 Warning [ACOS]:<TEST> Potential loop detected on Port 3 VLAN 709 Src MAC 001f.a011.58a2 Dst MAC ffff.ffff.ffff
Mar 31 2015 14:35:24 Warning [ACOS]:<TEST> Potential loop detected on Port 3 VLAN 710 Src MAC 001f.a011.58a2 Dst MAC ffff.ffff.ffff

[...]

Mar 31 2015 14:26:30 Warning [ACOS]:<TEST> The total broadcast packets 1002 per second on VLAN 710 has exceeded the configured limit of 1000
Mar 31 2015 14:26:30 Warning [ACOS]:<TEST> The total broadcast packets 1002 per second on VLAN 709 has exceeded the configured limit of 1000

 

Anyone has an idea how I could resolve my issue ?

 

Thanks & Best Regards,

Jean-Christophe

2 REPLIES
Fred_Mancen_1
Super Advisor

Re: Layer 2 loop issue

Hello.

 

Since you have a HA solution using these A10 load balancers, I think you are using a virtual IP address in this cluster scenario, am I correct? 

 

If this is the case, the better solution is to create a link-aggregation group in static mode (don't use the LACP enabled, just the static mode). Create an static ARP entry resolving the virtual MAC and IP Address, in order to the switch ignores the real MAC entries on the ports.

 

This will provide a failover link, working in active/passive way. In a similar case, it works well to me. This is a workaround and I am not considering any other settings supported by your A10 devices, ok?

 

The settings will look like this:

 

 

interface bridge N

description "description"

 

interface giga 1/0/26

port link-aggregation group N

 

interface giga 2/0/26

port link-aggregation group N

 

interface bridge N

port link-type access

port access vlan 710

 

arp static <ip_address> <mac_address>

 

Hope it helps.

Regards.

 

TPG-GVA
Occasional Advisor

Re: Layer 2 loop issue

Hi