Good Afternoon all
I am hoping for some advice

I have a unknown to me issue i was hoping for some assistance with.
I have a cluster of mikrotiks C2116-12g-4s each peering with a different ISP, We advertise two ranges x.x.x.0/24
on the mikrotik i have setup a vrrp with a /29 network in this range x.x.x.72/29 with the interface/gw address being x.x.x.73/29
I have a srx300 firewall I configure the wan interface to have the ip x.x.x.74/29 with its next hop being x.x.x.73
My SRX will gain internet access but after a few min the connection drops, then after some time the connection comes back for a few min then drops again. It just keeps repeating this cycle
If i reconfigure the vrrp to be the whole /24 and give my srx an ip of x.x.x.74/24 with a next-hop of x.x.x.1, the connection stays connected.
I run a traceroute from terminal with scr-address set to x.x.x.73 and it doesn't leave my ISP's network

To add to my confusion.
I have tested this vrrp network by configuring a windows vm with the IP details of x.x.x.75 subnet 255.255.255.248 gw x.x.x.73 and it has internet and keeps its connection

My SRX will gain internet access but after a few min the connection drops, then after some time the connection comes back for a few min then drops again. It just keeps repeating this cycle

I've had this happen a few times in my learning. It is caused by a routing issue.

When this happens to me it is usually a tunnel of some kind.

A-B-C

A connects to C through B, a tunnel is created between A and C, when that happens A to C through the tunnel is seen as a better, more direct route, so the route is adjusted, when that happens, traffic dies because without B in the middle, the tunnel dies.

It times out, the tunnel collapses, and traffic resumes using B.. When that happens the tunnel comes back up, BGP reestablishes, takes effect and it drops again.

Over and over..


This is usually the cause when it happens to me.