Hello together,
I am pretty new to the routing business, still some knowledge is there. With my first installation, I am quite amazed how easy loadbalancing and failover can be set up with an ERX.
Now there is a new project, which might be a little more tricky and I am searching for some advice:
We have a couple of sites (say 4) which are located nearby so it will be possible to link them using some airMAX p2p connections. It is also planned to put an ERX at each of these sites. Some of them (say 3) have one or two WAN uplinks. At each of all the sites, there should be one LAN (+WLAN) available, and each device connected at any of these LANs should be able to directly connect to any other device at any other LAN. The WAN uplink of any device should be load-balanced over all uplinks at all sites as there might be some period where quite a lot of traffic is originating from a single node (can be split up to multiple flows).
There are also some more constraints:
(1) A routing loop, sending WAN traffic twice over an airMAX p2p-Link should be avoided.
(2) If any p2p link fails, the LANs might get disconnected from each other, however WAN uplink should stay alive at any site (or subset of sites) independently.
(3) It should be possible to connect any client to any LAN and it will be automatically configured.
(4) It would be nice to have all LANs in the same subnet, but this has low priority.
(5) If this is still not hard enough, it might be nice to add an failover for the inter-LAN connection over some VPN if the p2p links fail. But this definitely has the least priority.
My thoughts are as follows:
To avoid the loop (1), there should be a different router at each site which is advertised via DHCP to only the clients at that very site. This might be difficult if all LANs are in the same subnet but should be easy with multiple subnets and static routes. Each router can do loadbalancing on its WAN-Ports (if any) independently.
All airMAX p2p-Links can be put into a common transfer-subnet. Is it a good idea to run OSPF on this net, such that the routers will learn about other WAN-uplinks? Will they start loadbalancing over the other uplinks automagically? Or is it a better idea to add static uplink routes over the other site routers and add them to the loadbalancing group? But how can a loop be avoided in that case?
Maybe a little weird idea, can it be sensible to put every WAN uplink into a separate VLAN, which is available on every ERX (distributed via wireless p2p links) and they do their WAN loadbalancing completely independent of each other?
I am quite curious about any suggestions.
Thanks a lot, Tobi