Adding 2nd fiber connection to DR site

[ckunz]

Good morning, hopefully a simple answer to this question.  we have a trunked p2p fiber connection between our main and DR sites 3850s.  We want to add a second fiber connection for redundancy.  Would this be as simple as trunking the new fiber and allowing the same vlans as the 1st fiber across the circuit?  Will the two fibers auto load balance?

thanks for any ideas on this.

[Georg Pauwen]

Hello,

a port channel (which would automatically load balance) would likely be the best and simplest solution.

[Giuseppe Larosa]

Hello @ckunz ,

as already noted you will need to configure a port-channel at both sides on both links to achieve load balancing.

If you add the second link as an indipendent  L2 802.1Q trunk STP will run on it and on the existing link and one side will end to be in blocking alternate ( depending on the position of the root bridge for each VLAN if you are running PVST or Rapid PVST).

The use of LACP is recommended for building and monitoring the port-channel, but you need to verify if LACP message frames can pass both sides on both links.

Hope to help

Giuseppe

[paul driver]

Hello
Create a port-channel on both switches pertaining to the old new/trunk interconnect.

Add the new P2P interface into the PC and then fiber the connection, let the L2 PC trunk link establish, As/when you are ready disconnect the 1st P2P interfaces and default them (Depending on the STP mode you are running you should have very little convergence upon disconnection) then reconfigure them for the new PC and reattach.

[ckunz]

Thanks for the info, once the second p2p is finished being installed I will setup a PC for the two interfaces on both ends.  I will let you know how I make out.