Interlink between the two backbone switchs

Question:

We are operating the two backbone Cisco 3560 switchs for redundancy with hsrp and eigrp.

I am wondering if I connect the two links (trunk and L3) or just one port (trunk or L3) between the backnone switch.

I attached the diagram that simply indicates the my concers.

In this case, what would be the best option ?

Please give me a recommendation.

Answer:

both HSRP and EIGRP requires L2 adjacencies so you need a L2 trunk on all the involved Vlans between the two switches.

If you like you can add a separate L3 link between the two as an added protection.

The minimum is a L2 trunk, you should consider the use of an etherchannel bundle with two member links configured as 802.1Q L2 trunk. In this case I recommend the use of LACP ( mode active) for better resiliency ( bundle only if LACP messages are exchanged on Cisco 3560V2 Price each member link)