I am planning to book a block of 8 fixed IPs so I can route incoming connections differently based on the IP they come in on.

For example, port 25 on IP1 must go to Server1 while port 25 on IP2 must go to Server2

I have not tried it yet, but it seems that Port Redirection allows me to select each IP individually and forward to separate servers.

On the other hand Open Ports just allows me to select the interface but not the IP.

Why this limitation? It means that I cannot use Open Ports and am limited to 20 entries. If I use 6 IP to direct ports to 6 servers all I have is 3 ports per server.

Also, Port Redirection only redirects one port at a time. For a single FTP server I need 3 ports plus a range of several contiguous ports to be forwarded, so not possible to be done.

Am I correct in my understanding?

Have you listed the block on IP Alias' you have for your external subnet?

You need to do the above 1st and then use OPEN PORTS and you will then get the option for what address to you,
Here I have a customer with a /29 sunbet for 6 useable IPs

Even with one IP I can see that option on Port Redirection as it has a field "WAN IP" and a pull-down list which shows just the one IP.

I was asking about the Open Ports section which only has a choice of WAN1 or WAN2 but no mention of selecting an IP and not even an option to select 'All' which is most unfortunate - as it means every entry must be duplicated if you have two WAN ports.

I have actually just ordered a ZyXEL SBG3300-N which seems to have a much more flexible way of defining port openings.

The above it a screen shot from Open ports (and its a 2850 as well).
Port re-direction and open ports are effectively the same hence why you only have one option on newer kit like 2960 3900.

Have you specified your IP addresses in the IP Alias table? If not you will not get the option to select a specific the IP address only the WAN interface

IMO I wouldn't touch a Zyxel!
Cisco, Juniper or Draytek all the way 8)

sicon wrote: The above it a screen shot from Open ports (and its a 2850 as well).

Can't see any screen shot. Where 'above'?

sicon wrote: Port re-direction and open ports are effectively the same hence why you only have one option on newer kit like 2960 3900.

About time too!! The 2850 is not so old

sicon wrote: Have you specified your IP addresses in the IP Alias table? If not you will not get the option to select a specific the IP address only the WAN interface

The multiple IPs are being ordered for an other site so I cant try in advance.

I don't think you are quite right - at least with my model. My gripe is that port-redirection has been 'modernised' and it contains for 'WAN IP' the options:

All
WAN1 IP Alias [1]

If I had more IPs or a 2nd WAN (which I normally have but is disconnected at the moment) then I presume they would all be listed.

So port-redirection is OK but suffers from:

Limit of 20 entries
No facility to define port ranges

When we move to Open-ports we have 20 entries with each having 10 port ranges. That is good except that in place of 'WAN IP' we have 'WAN Interface' and that shows WAN1/WAN2/WAN3. No mention of any IP and even more serious is that there is no mention of 'ALL'

So with my two WAN connections, I have to set up every open-port section twice, cutting the total entries to 10 and it would be three times if I had all 3 WANs in use - in fact I would not have enough space for all my servers with all 3 WANS in use.

Are you saying that with IP Aliases defined, more options appear in the Open-ports section undder 'WAN Interface' ?

sicon wrote: IMO I wouldn't touch a Zyxel!
Cisco, Juniper or Draytek all the way 8)

First I have heard of Juniper - looks like serious prices. I needed a specific spec urgently so I went for what was available at reasonable cost.