I'm a little bit late to the party here but elements of the solution have already been mentioned, one thing that hasn't been mentioned is the maximum recommended tunnel count for the MX600s because officially there isn't one. This stems from the fact when the MX400/600 were live we only published maximum tunnels as opposed to maximum recommended tunnels. However, based on my experience you should have the same sort of max recommended tunnels for an MX600 as you do for an MX450. The total aggregate bandwidth across all those tunnels is going to be less than the MX450 though, by about 2x. Meaning you might be hitting scaling issues of the encrypted throughput side even if your tunnel count is <1500. I am also presuming that you are running the MX600s in VPN Concentrator (VPNC) mode, as any dual/triple duty they need to pull in routed/NAT mode for firewall or UTM is going to have an impact too. Hopefully, you are in VPNC mode as that was the recommend design (for AutoVPN termination) then. Outside of that, the answer is horizontal load balancing (you might hear the SEs call it horizontal scaling) across multiple active MXs for pools of spokes such that: VPNC MX1 - Primary for remote site pool A, backup for pool C VPNC MX2 - Primary for pool B, backup for pool A VPNC MX3 - Primary for C, backup for B Again ideally the typical resource utilisation from a tunnel count/encrypted throughput perspective for each of those VPNC modes MXs should be ~50% of max (i.e. 750 tunnels and 500Mbps for hte MX600), ideally less so that in the event of a hardware failure, the failover MX of the failed primary isn't overloaded. This is because spokes create tunnels to both/all MXs they have configured as hubs and without knowing this you can easily go over your max recommended tunnel count and have a bad time. Also, if AutoVPN is configured this is further compounded by the fact the spoke MXs build over all transport networks too, so a spoke with 2 WAN connections to 2 VPNC mode MX build 4 tunnels total, 2 to each VPNC mode MX. If the hub mode MX is routed mode and also has 2 WAN connections this doubles again! Meaning that proper scaling does come down to where the customer is on the risk/cost spectrum! Outside of that, I would only recommend BGP from the MXs into the 'rest of the network'. This enables bilateral learning and does so efficiently, you are not the first person to complain that I took away everything but AS path prepending as an option but we did so because fundamentally BGP is an EGP, and EGPs need that sort of complexity. The problem is nowadays BGP gets used effectively as an IGP, you could argue we use it as such, as both sides of the eBGP relationship you need to configure will be under the same administrative control. As such we simplified it for the majority of customer use cases, if you can tell me a reason to expose MED or local pref that we can't already accommodate with some other aspect of design I will make sure it's in the next iteration of BGP! Please don't confuse conscious design to help people build and support networks easily with 'fisher price networking', yeah sure you might have always built networks like this' but we also used to used Frame Relay and ATM and I for one don't want those days back! So, maybe look at the recommendations we do have with an open mind because we didn't make it that way to annoy some folks, we did it to help the most folks. On the CVD front, more are coming so watch out on the documentation site and if you need some more bedtime reading here are a few of the kbs we have in and around this topic (if my boring post didn't put you to sleep my boring kb articles might 😉 https://documentation.meraki.com/Architectures_and_Best_Practices/Cisco_Meraki_Best_Practice_Design/Best_Practice_Design_-_MX_Security_and_SD-WAN/Meraki_SD-WAN https://documentation.meraki.com/Architectures_and_Best_Practices/Cisco_Meraki_Best_Practice_Design/Best_Practice_Design_-_MX_Security_and_SD-WAN/SD-WAN_Internet_Policies_(SD-Internet) https://documentation.meraki.com/Architectures_and_Best_Practices/Cisco_Meraki_Best_Practice_Design/Best_Practice_Design_-_MX_Security_and_SD-WAN/Meraki_Auto_VPN_General_Best_Practices https://documentation.meraki.com/Architectures_and_Best_Practices/Cisco_Meraki_Best_Practice_Design/Best_Practice_Design_-_MX_Security_and_SD-WAN/General_MX_Best_Practices Cheers Steve
... View more