Hi,
I’m trying to add our new Mikrotik CRS518-16XS-2XQ-RM switches to our network in a way that we have full redundancy, while avoiding loops, but I’m not sure what the best approach is. Maybe someone here can provide some pointers.
Current situation
- We have 2 ISPs, connected through BGP with 2 routers (Edge1 and Edge2)
- Between the 2 routers we have a small subnet (let’s say 200.0.0.248/29) on which they share iBGP and on which traffic can be forwarded → green line in diagram
- We have 2 switches (called Core1 and Core 2) that are Ubiquiti EdgeSwitch 16 XG
- There’s a connection from Edge1 to Core1 and Edge2 to Core2 and also between Core1 and Core2 → blue lines in diagram
- The servers are connected (using a linux bond in active-backup) to both Core1 and Core2
- The blue network has IP subnet 200.0.0.0/25
- Edge1 and Edge2 have VRRP running on the blue network, so they share 200.0.0.1
- The result is all servers can reach the default gateway 200.0.0.1 and from there traffic is routed to the ISPs
With the Mikrotik switches
- Ideally we’d like to add the Mikrotik switches behind the Ubiquiti switches, since we don’t have enough ports on them to simply replace them outright
- We need to interconnect the Mikrotik switches with 100Gbps because we’ll be using the 25Gbps connections between a set of new servers
STP ?
- I was first thinking of using RSTP or MSTP to cut any loops between Core1 and Mik1 or Core2 and Mik2, so the high speed link between Mik1 and Mik2 would not be cut and the one betwen Core1 and Core2 would also not be cut. This way traffic would go smoothly from all servers to all other servers and to the Internet
- However when trying this, as soon as I complete the loop, it simply won’t stop looping, even though RSTP was enabled on Core1, Core2, Mik1 and Mik2 and all root bridge and priority settings seem to be correct
- I’m not sure if this is the way to go, even though it seems the easiest solution
Other options
- OSPF seemed like another option, but sadly the Ubiquiti switches don’t support it
- I could swap the Ubiquiti and Mikrotik switches around, but that still won’t solve the problem, unless I create a separate routed network on that side as well and then use VRRP on the Mikrotik switches, but it makes things a lot more complicated
Maybe I’m just missing the most obvious solution here ?
Any help most appreciated !
