Attn : Networking Guru's

byrnenj

I am setting up a network, with mail server running on one of my static IPs.

The network is connected over Broadband, and I have a /29 IP address range, giving me 6 usable addresses.

What I'm wondering doesn't really affect the usability of the system, it's just really a general query...since I'm just trying to get into this!

Should I always assign the first usable IP to my router and then use whatever IP's I want after that for other services etc.

Is there any definite answer on this?
Do Cisco or anybody like that recommend such a procedure?

Thanks for your help!

LoLth

normally we use a 4 ip address range

x.x.x.1 - x.x.x.4

1 is left for internal facing
2 is the router
3 is the firewall
4 is ... ehh, I never thought to ask what that one is for

on combo firewall/router (zyxel 662 etc) I just assign 3 as the wan facing IP. Though usually just a single static is requested.

for your static mail server you'll need to put a NAT entry into the firewall to channel port 25 traffic to the local IP of the mail server.

(I assume you are talking about a mailserver operating over a wan and not just an internal setup).

Never set up a 6 address range. I would guess it's 3= router and 4=firewall

hey! if this is right, does that make me a guru? already working on the beard and have my eye on a lovely cave halfway up K2, it's even got a little garden path leading up to it for the curious to come and ask questions... I'll more than likely have a hangover though so they'll just get a stream of abuse for disturbing me...

byrnenj

OK say my public IP range is 123.456.7.8/29

123.456.7.9 : Netowrk
123.456.7.10 : Router WAN <- Should the router always be first usable
123.456.7.11 : Mail Server
123.456.7.12 : other stuff
123.456.7.13 : spare tyre
123.456.7.14 : the kitchen sink
123.456.7.15 : dgjha
123.456.7.16 : Broadcast

Would this be industry standard?

LoLth

yep, you're right.

Had to have a quick check but essentially

1: network address
2: router
3,4,5,6 etc: any can be assigned to firewall as you see fit
last ip: broadcast.

byrnenj

Does it say anywhere that this is the standard?

jayok

Interesting this, I always use the last Public IP address range for the router!

TBH it doesn't matter which IP address you go with, first, last, middle, etc. Normally most people put the router first at this is the first device configured for the line and is/was installed by the ISP and the engineer picks the first. Other reasons for picking specific IP addresses within the range would be if you ISP is managing the router, they may specify the IP address to use.

Other than that pick away. Installations vary widely.

JayoK.

liamo

I don't ever remember reading that a gateway address should be the first usable address in a subnet, but this has been the case in most networks I've come across.

In a couple of other networks the last usable address in the subnet was used for the gateway. This is actually the case in my current place of work - a situation I inherited and one I intend to change at some point.

While it's certainly traditional that the first usable address is used for the default gateway I don't believe it's a standard or best practice. Of course, I'm happy to be corrected on this point.

Regards,

Liam