Ring network with Mikrotik and Cisco

RouterOS General
1

Hello all,

I would need some help with this since i come from cisco way of thinking of network so all this Mikrotik stuff is new to me.

Basically we have a ring network with 5-6 switches in different locations/buildings. Core is Cisco 3750, Layer3 switching is done on him. There is about 5-6 VLANs that are needed to have available on all switches.

For the argument sake let’s say there is 3 mikrotik switches, but concept is the same if there was 10 of them. Here is the schematic of it:

So idea is if link is broken at any point switches will still stay connected. It would be better if it is star design but this is only option available for now.

And if link is broken:




So it is a relatively simple thing.

Since on Mikrotik switches it is L2, i have to user (R)STP for link detection, so no RIP/OSPF and other protocols can be used. With RSTP on cisco i have great results but when it is used on cisco only equipment. This is the first time we combine Cisco and Mikrotik.

So question for you ppl is how would you do this?

As i understood (and knowledge of mikrotik is very limited, started learning it a month ago) i have to make VLAN (lets say 10) that is on some interface (lets say port sfpplus1), make bridge, add that VLAN to that bridge and there we set up path cost lets say 10? But then i have a problem how to do same thing with other port sfpplus2 with path cost lets say 20. I cant use same VLAN it is used, so i make new vlan with same vlanid (10) and add it to new bridge, and to new port (sfpplus2) and there i can set up cost 20. Here is where things are complicated :slight_smile: it will be problematic to add VLAN to some ethernet port, because it depends to which SFP port is traffic going, and so and so.

So basically this is a bad design i think, and that is why I’m here to see if someone has some idea how to do this.

Thx in advance!

2

RouterOS does support loop protect mode. RouterOS also supports RSTP on bridging interfaces according to the wiki.

I’d avoid that all together, myself. If I were working on your network, I would setup all switches as L2/L3 and utilize OSPF to handle the packets flowing over the links to get around the network and outside of the network.

Without knowing the size of your network, I would create a /22(can be further subdivided) to live on each switch. Each switch would handle DHCP within its domain and facilitate communication between the different networks. Your main 3750 would be configured to advertise the default route into OSPF for all of the other switches. All other switches would simply advertise known networks/routes and you can call it a day. This would also make it easier down the road should you need to upgrade your 3750, or any L3 switch for that matter. It would also mean that your design (high level) would be vendor agnostic.

Quite frankly, I believe you are putting too much on to your 3750 to begin with. It’s an old switch and you may very well run into performance issues down the road - again really depends on the size of your network. Does the 3750 connect to a router for your WAN Access? I imagine it does as the 3750 does not support NAT last time I checked. You’ll also want to ensure you are running version 15.0+ IP Base or Advanced IP Services to have access to OSPF.