[BGP] Time till new route is used

RouterOS Forwarding Protocols
1

Hello,

I have 2 BGP Speaking CCR which also speaks IBGP to each other.
Now I inject a route on one CCR setting a new next-hop for a specific route.
This works and both CCR receives this new route and I can see that the new route is the active one on both routers.

So far so good but its looks like there is a delay of around 20-30 seconds between coming active and actually being used for this new route.

I guess this is because it took some time to copy the new route to the forwarding table?
Is there a way to enforce this route becoming used faster?

Regards,
Michael

2

There are two possible reasons:

  1. The one you mentioned
  2. Route cache

First you can fix by getting faster CPU :slight_smile:
Second is not configurable and managed by linux kernel.

3

Hello,

faster cpu is not an option as both routers are CCR1036-8G-2S+ which are at 0.00 CPU Load :wink:.

its a bit weired as the first router is nearly 10 seconds faster than the second one.
Even when I inject the route on both routers at the same time the second one needs 10-20 seconds longer until the new route is used so I guess your second opinion (linux route cache) might be right.

4

When the old route becomes invalid, it works faster.
But the cache indeed can sometimes cause problems, I have also seen this in other Linux devices.

Good news for you: newer Linux kernels don’t have this cache anymore. So when MikroTik finally releases
a new RouterOS based on newer Linux kernel, the problem will be gone.