I like configue L2TP VPN two mikrotik Router.

The tunnel setting up good end connecting.
I use this
http://www.mikrotik.com/documentation/m ... /L2TP.html

But, I transfer the parameters for my network and try setting up route not working.(UNREACHABLE)

My network:

SERVER SIDE:

ether1: WAN connecting public IP and connect here L2TP.
ether2: DHCP server to the clients: IP: 192.168.88.1 (network 192.168.88.0/24)
L2TP local address: 10.0.20.1 remote address: 10.0.20.2

Client side:
ether1: DHCP client not PUBLIC IP. ip: 192.168.10.20 (network 192.168.10.0/24)
same the remote network other clients

The VPN tunnel connecting I can ping vica-versa the 10.0.20.1 and 10.0.20.2

I try USE the dokumentation, routing schema, but not good:

server side > ip route add dst-address 192.168.88.0/24 gateway 10.0.20.1
client side> ip route add dst-address 192.168.10.0/24 gateway 10.0.20.2

??????

Use mangle in prerouting chain to mark-route traffic. In sideA with src-address of sideA to dsc-address of sideB and in sideB with src-address of sideB to dsc-address of sideA.
Note that you can use CIDR format in src-addresss and dsc-address filed of mangle.
now use your routing-mark in /ip route.

server side > ip route add dst-address 192.168.88.0/24 gateway 10.0.20.1
client side> ip route add dst-address 192.168.10.0/24 gateway 10.0.20.2

??????

Isn't this backward?

Wouldn't you want

Server Side = ip route add dst-address 192.168.10.0/24 gateway 10.0.20.2
Client Side = ip route ad dst-address 192.168.88.0/24 gateway 10.0.20.1

cbrown is right.
Also you must always check your ping RTT time. It must not be less than the RTT of your route without tunnel form SiteA to SiteB.