Hello.

I have around 20 of 24bit subnet from ISP.
and I distribute IP to PPtP Client with ROS machine.
Recentrly my ROS machines's CPU load reached max 80%
there are around 700 PPtP connection constantly.. and traffic is just 40mbps total. don't know why that so high CPU load..
Server is 2 intel xeon 2.4Ghz(enabled HT, it seems like quad CPU) with 2G Ram and 2 GBE bonding for 1 ip address, ROS 5.0RC1
Anyway i decide to add more server for PPtP service.
Here are my network diagram. I want add Additional server in same subnet with Existing server.(xxx.xxx.xxx.0/25) they using same gateway xxx.xxx.xxx.1
ISP guy said they will set route all aaa.aaa.aaa.0/24~kkk.kkk.kkk.0/24 subnet to both of my servers
but when they did, all my client can not browse anymore. because client's request was going well to destination but when response receive at ISP main router, it distribute to both ROS machine with round robin way. so PPtP connection was OK but can't browse. so i ask to ISP guy to rollback to old configuration for a while.
maybe i can spirit assigned subnet and customer group for each ROS server. but it will be hard to manage later when i add more servers.

I heard about OSPF can achive this job. but I can't really understand how OSPF work.
so please let me know how can i achive my goal.

Thanks advanced.

Sean lee

OSPF could work, but then you would need OSPF on the ISP Main router as well. If that's not yours to control then perhaps using proxy-arp based solution instead.
Proxy-arp is found as an option in the main window of the (ethernet) interface in question. Normally ARP is set to "enabled", but it can be set to "proxy-arp".
Read up on it and be sure you know how to it works before you enable it (or really bad things can happen and things break in mysterious ways).