I have a Mikrotik CCR1072 running version 7.20.8 firmware.
This MT has a GRE tunnel with a Cisco 3750.
I am using the FW Mangle rule to set the MSS TCP to 1436 and on my tunnel, I set the MTU to 1476. Typical stuff for a GRE tunnel due to the 24 bytes overhead.
Fastpath is disabled on the tunnel.
The FW rule is not getting any traffic and the tunnel is up.
The FW rule is applied outbound on the GRE tunnel interface per the documentation.
Any help is appreciated.
If you think it is an MTU/MSS issue, the cisco tcp adjust-mss will affect the MSS in both directions. So if you apply it to the cisco side tunnel, and it starts working, then something in the mangle probably isn't working as you think it should.
What troubleshooting have you done? Sniffed any traffic?
Hi Buckeye. sorry for the delay.
The tcp-mss adjust is applied to both sides of the tunnel.
The tunnel is up and working although I still do not understand when I use Mikrotiks on either side the tunnel I can only get 25M+/- through a 1G tunnel connection. The CPU on the MT’s are very low so its not stressed and I am passing UDP traffic in both directions.
As far at T-Shoot I did a pcap on the MT side and my test devices only pass UDP traffic through the tunnel.
I am not dropping any packets, but my devices show overflow and underflow issues. They are IPMux RAD devices and extremely sensitive to network latency and other network related issues.