Safety bridges. 1+1 instalation.

RouterOS Scripting
1

Hello.
I have a strategic link between two points (distance 5000m). I need to make it totally trouble-free so I’ve decided to link up another point using different interfaces and antennas to make a triangle. Anybody has some experience with that kind of scripting?

So… Stage 1:
bridges.png
There are three ALIX 2C2 boards with 6 WLAN interfaces. It generates two independent paths from MAIN ROUTER to CLIENT ROUTER. Lasst ALIX on client side should decide which interface to use, but “main” is always primary. When “main” fails, it shoud be max 10 seconds to switch on “backup”.

Stage 2:
bridges2.png
There are five ALIX boards with 6 WLAN interfaces and one RB150 board. CLIENT ROUTER is pluged in to RB150 ETH2, ALIXes on the CLIENT side are pluged in to RB150 ETH0 and ETH1. In this case RB150 should decide which interface to use (eth0 or eth1), but “main” (eth1) is always primary. When ETH1 fails, it shoud be max 10 seconds to disable ETH1 and then enable ETH0. But maybe there is other method?

All devices are in the same subnet with public IP addresses. Traffic is about 3-4 Mb/s HDX. Throughput on both paths is about 30 Mb/s TCP HDX.

Any ideas how to configure/script it? Any experience with similar instalations? Any bad feelings?


Big, tasty beer to anyone who can help :slight_smile:))


Best regards

Kuba

2

Are you looking at using both links simultaneously (load-balanced)? In that case, you’ll need EoIP + Bonding.. more of it here http://wiki.mikrotik.com/wiki/Bonding_Examples
In your setup I wouldn’t recommend it, since one of your links has more hops than the other, bonding will effectively slow down all your links to the slowest one.

If you just want one of the links (eg. the backup) to be just a backup, and use it only when the main link goes down, Bridging with RSTP is the way to go. just bridge all your links and enable RSTP on all the bridge interfaces. With your setup, the routers should realise that your backup link has a higher cost (ie. more hops), and will use the primary link. If the primary link goes down, the backup kicks in automatically.

3

PS: off topic, but what did you use to draw those graphs? they look way nicer than what Visio can do.

4

Corel Draw 9 and Paint Shop Pro 9 :slight_smile:))

5

Why not use OSPF to make it a full duplex connection over the 2 links?
Decreases your latency and if one does go down you’ll just fallover to the remaining link.