Hello everybody! Again!

Another interesting problem.

For example, i have 2 web servers behind NAT with IPs 192.168.1.5 and 192.168.1.6

And I have only one WAN (extrernat internet IP) and only ONE... port - 80

I need, to... if first web server will out of rage, the second (reserve) will being accessible instead of the FIRST!

If it's looks like routes - there is no problem - distance=1 and distance=2. BUT... if it is 2 servers behind NAT... can they be exchangeable if first server will offline?

Here is a standard rule for internal web server, behind NAT... to bee accessible from the Internet:
So... is it possible to access second NAT server if FIRST will be lay down?

HOW-TO... do what automatically, please HELP!!!

Hello everybody! Again!

Another interesting problem.

For example, i have 2 web servers behind NAT with IPs 192.168.1.5 and 192.168.1.6

And I have only one WAN (extrernat internet IP) and only ONE... port - 80

I need, to... if first web server will out of rage, the second (reserve) will being accessible instead of the FIRST!

If it's looks like routes - there is no problem - distance=1 and distance=2. BUT... if it is 2 servers behind NAT... can they be exchangeable if first server will offline?

Here is a standard rule for internal web server, behind NAT... to bee accessible from the Internet:

Code: Select all

add action=dst-nat chain=dstnat disabled=yes dst-address=31.31.31.31 dst-port=80 protocol=tcp to-addresses=192.168.1.5 to-ports=80 

So... is it possible to access second NAT server if FIRST will be lay down?

HOW-TO... do what automatically, please HELP!!!

You could write a script and use netwatch... when server 1 stops responding to pings then switch to server 2. I don't know of a built in way to do it.

You could write a script and use netwatch... when server 1 stops responding to pings then switch to server 2. I don't know of a built in way to do it.

I very appreciative your affort for help, but... it's NOT a help. Sorry!

Can somebody tell, if it possible to make route like rules with distance priority to change the route from current to reserve (like distance=1 and distance=2)? Is that possible to make such like rules for resources behind NAT??? AND HOW?????

Please somebody!!!

There's no "distance" for firewall rules and the first suggestion was right:

ros code

/ip firewall nat
add chain=dstnat dst-address=31.31.31.31 protocol=tcp dst-port=80 \
    action=dst-nat to-addresses=192.168.1.5 comment=mainwww
add chain=dstnat dst-address=31.31.31.31 protocol=tcp dst-port=80 \
    action=dst-nat to-addresses=192.168.1.6 comment=backupwww
/tool netwatch
add host=192.168.1.5 interval=1m timeout=1s \
    up-script="/ip firewall nat enable [find comment=\"mainwww\"]" \
    down-script="/ip firewall nat disable [find comment=\"mainwww\"]"

There's no "distance" for firewall rules and the first suggestion was right:

ros code

/ip firewall nat
add chain=dstnat dst-address=31.31.31.31 protocol=tcp dst-port=80 \
    action=dst-nat to-addresses=192.168.1.5 comment=mainwww
add chain=dstnat dst-address=31.31.31.31 protocol=tcp dst-port=80 \
    action=dst-nat to-addresses=192.168.1.6 comment=backupwww
/tool netwatch
add host=192.168.1.5 interval=1m timeout=1s \
    up-script="/ip firewall nat enable [find comment=\"mainwww\"]" \
    down-script="/ip firewall nat disable [find comment=\"mainwww\"]"

Sob, thank you very very much for such explication!!!

It's really great device - Mikrotik, with great support

The other way to do this is to have an "pseudo" IP address like 192.168.2.1 on both Web servers as an alias.

They you route 192.168.2.1 via 192.168.1.5 with distance 1 and via 192.168.1.6 with distance 2.

If 192.168.1.5 stops answering the ping, the route will go inactive and switch to the backup route.

You can also use a similar technique to roughly load balance the web server

After i read your first post, it seems you need to balance the load of input web traffic and do failover.
The standard way is use DNS load balancing: Imagine google web servers, when you want to access google.com it may have different IP addresses in each request. This feature is called DNS load balancing.
But with routerOS i think there's only NetWatch and scripts as tools to implement this feature as mentioned by other guys in post 2 or 3.