Strange switching question

RouterOS General
1

I have a bit of an odd question. We have a RB1100AHx4 in our office that does all the heavy lifting for our network. At our tower which is about 800Ft away, we have a CSS326-24G-2S+ feeding various radios for links and access points.

We go from one to the other using Cat6. Actually we have two cat6 running out there. The older one had issues and we ended up replacing it. Then my boss told me to fix the older one as a backup. Last night we had issues and had to switch back to the older one. Is there anyway to automate switching between the two? Leave them connected full time and switch from the new one to the old one when it goes down. The last time was due to a Porcupine that found the cable tasty. Have not yet found the problem this time.

2

Uh … legal limit of any kind of ethernet is about 100 metres which equals 328 feet. Which means your connection with length of 800+ feet is bound for problems whatever you do. Even when considering modern multimode fibre cable, your distance is just within legal limits (300 or 400 metres or roughly 1000 to 1300 feet).

To your question: I’ve two ideas (none tested, so use them carefully):

  1. use both links in backup mode … so connect both, but disable one of ports on RB1100. If the link fails, disable the (until that moment) running port and enable the other one. Don’t do it on CSS, it’ll be inaccessible when the running link fails.
  2. create bond, seems that you’ll have to run it in 802.3ad mode (ROS supports many different modes, I’d go for active-backup but doesn’t seem to be supported in SwOS) … when one of link will fail, the other will take over the traffic … and will do it much faster than you would do manually (as per bullet #1). Bonus is that you get higher capacity when both links are fine
3

The newer link we are using GPER’s every 200 ft. And in the older link, built before me, they used switches to boost the signal along. Not pretty, but it works. Everything uses static IP’s.

Thanks for the thoughts, I had not thought of #2.

4

As you mention switches used to extend the link reach (GPERs are switches as well, just pretty well disguised), if you go the bond way you’ll have to use ARP monitoring (I guess MII monitoring won’t trigger if some intermediate segment breaks, the closest segment will still keep link up).
It’s not really clear if SwOS supports ARP link monitoring though … seems you’ll have to find out (and please report back …)

5

Will do.
Thanks again.