Handling multiple WAN circuits

[m.glosson]

Greetings. We have recently signed up for Metro Ethernet for our main campus and 8 branches. It's a "mesh" with the carrier providing a virtual layer-2 switch in the cloud. I have a router at each site running EIGRP and they all have neighbor relationships with one another.

The carrier has provided a second circuit into the main campus, which comes into a different building via a completely diverse path. That's good because there's a lot of construction going on at the main campus. I'm trying to think of the best way to provide failover. Load balancing isn't necessary since each branch has 100 Mbps and the main campus has 1 Gbps, so even without load balancing, there's no way that the 1 Gbps could be saturated. That connection is currently terminating in an ASR1001-X at the main campus.

Each campus also has a backup Internet connection running between 7 and 60 Mbps terminating via DMVPN into an ISR-4431. I mention that because I'm fine if terminating the second Ethernet WAN connection is done in the same ASR1001-X as the “primary” line if that makes it easier.

Here are some possibilities, but I have problems with each one:

• Have a normal interface and a backup interface. However, since the WAN connections terminate into a CPE, the link light probably wouldn't go off even if the back-end connection is experiencing trouble. I saw an article on Ethernet CFM but haven't really looked into it yet.
• See if the carrier supports VLAN-trunk interfaces. That way I could have two virtual connections at each branch and let EIGRP manage what's up and down based on keepalives/neighbor relationships. This would also provide load balancing (which I don't really need).

Anybody had this scenario and found an ideal solution?

[trfinkenstadt]

Hello,

Are you running EIGRP on the Main campus environment?  Do you care if the communications go one way or the other?  

For quick solution:  Manipulate bandwidth or delay metric of the interfaces in the Main Campus to ensure it prefers the primary/original path to your branches and let EIGRP do its calculations.

Int Gig0/0

 delay #####

!

This also won't make your utilization percentages look funny in your tools.

best regards,

tim

[Collin Clark]

Do you know if both links go back to the switch at the carrier? If so you could Etherchannel the two links.

You could also use a route-map and advertise the backup link with a higher AD.

Since it's layer 2 you should be able to HSRP/GLBP on the WAN side and track the interface states.

You could DMVPN that WAN and configure a dual-hub.

They more than likely support QinQ (most Metro-E does) so you could do your PVC.

Some of the above depends on the carrier. Etherchannel is what I prefer and usually ask for.

HTH

BTW: IMO don't tweak the BW statements. If you want to manipulate routes, only use delay.