HSRP "Split Brain" on the STP Topology

[mitsuyuki5846]

Hello. I'm a network administrator in my company.

I have a question about HSRP "Split Brain" on the STP Topology.

verifying to HSRP Down Time that attached network topology.

Trying "ICMP Ping" from PC to HSRP Virtual IP.

I have found unexpected senario. PIng goes down when reboot the L2 Core SW 1 and Router 1 HSRP goes Active from Init Status.

Why ping goes down?

Router 1's Gratuitouse ARP, It's should not be transffered to L2 Core SW 2?

Sorry to trouble you, Could you please teach.

[Rajeev Sharma · Accepted solution]

Hey,

Regarding your questions:

1. Ping goes down when reboot the L2 Core SW 1 and Router 1 HSRP goes Active from Init Status.- It will as it cant receive HSRP hellos from other peer.

2. Why ping goes down? - Check the cam table on L2 floor SW 2960 for the mac address of virtual IP address and probably we will find why ping goes down.

3. Router 1's Gratuitous ARP, It's should not be transferred to L2 Core SW 2? - Yes, it should not. Did you check the mac address table on L2 core SW2 and found change in hardware address?

HTH.

Regards,

RS.

[mitsuyuki5846]

Thank you for your reply, rejeevh. I retried "L2 Core SW 1 Down Test".

From a result, My verification senario was wrong.

It was not shown in the figure, there is another link of both routers to other routers over the Core SWs that enable OSPF and "redistribute connected" in practice.

"ping from PC to HSRP Virtual IP" was wrong. "ping from PC to another OSPF Router's Interface" is correct senario.

I verified correct senario rebooting L2 Core SW 1. Also, ping goes down.

but this result was simple, It was dropped at SW 1's EtherChannel Interface in STP LIS/LER status when recieved return packet from another Router. (SW 1's other Interface was enabled Portfast or Portfast Trunk. )

I was confirmed the result was improved, It was enable Portfast Trunk in Etherchannel Interfaces of SW 2 and SW 1.

Thank you very much for your reply.