Meraki Warm Spare Failover

[AlexLIO]

Hi All,

I have a question in regard to the warm spare failover process.

Here is the configuration:

2 Separate services - ISP 1 - 1GBPS. IPS 2 - 500MBPS

Primary MX - Uplink Port 1 from ISP 1. Uplink Port 2 from ISP 2.

Secondary MX - Uplink Port 1 from ISP 1. Uplink Port 2 from ISP 2.

I understand how failover works on the whole but I want to know what happens in this particular scenario. However unlikely it is, what happens if I lose the Uplink on Primary MX 1 Port 1?

Does it failover to Primary MX 1 Port 2, or does it failover to Secondary MX 1 Port 1?

The reason I ask is that obviously if the 1GBPS service is still available on the secondary port 1, we'd ideally like to use this rather than the 500mbps service on the Primary MX on Port 2.

Any advise would be much appreciated.

Thanks

[NolanHerring · Accepted solution]

Out of curiosity, which model are you using?

Also assuming your using a vIP?

The primary MX (if it is up) will always be the path taken. The secondary MX only gets used if the primary device is goes down and VRRP packets stop flowing from it.

Meaning if WAN 1 goes down on Primary, WAN 2 on primary will take over.

Reference doc:

https://documentation.meraki.com/MX/Deployment_Guides/MX_Warm_Spare_-_High_Availability_Pair

[AlexLIO]

Hi Nolan,

Thanks for the quick response. 

Correct, using vIP on the MX84s. 

I thought that was the case but just wanted confirmation. Not exactly what we're after but its definitely better than no failover.

Thanks again.

[NolanHerring]

Well I have good news and bad news lol

Good news is, because your using MX84, the 1Gbps circuit doesn't matter. The MX84 can only handle 500Mbps throughput (documented, and personally tested/verified). Which means that both circuits are actually now 500Mbps, so you can rest easy on that front of making sure your getting the fastest speed in the event of a fail-over. Your getting 500 either way you spin it.

Bad news is your paying for 1Gbps but only getting half of that =(

[NolanHerring]

For reference in case you need it:

https://meraki.cisco.com/lib/pdf/meraki_datasheet_mx.pdf

[AlexLIO]

No problem. this was theoretical. We have the MX84s but only a primary 100mbps service currently.

We're looking at our options on setting up a new primary so we'll make sure to not exceed 500mbps!

[NolanHerring]

You could always load balance WAN 1 and WAN 2 as long as the circuits combined don't go over 500 total in the interim. I've never done it but it can be done. All that SD-WAN magic sauce 😃