Community discussions

 
sgb32
just joined
Topic Author
Posts: 8
Joined: Thu Dec 15, 2011 1:50 pm

> 254 IPs

Thu Jan 05, 2012 3:05 pm

I’m going to need more than 254 IP addresses so I guess I'll need to configure an RB750 to lease class B IP addresses.

I assume that I configure a Pool of 192.168.0.1 – 192.168.1.254 on the 192.168.0.0/23 network for example and have DHCP use it.

I’ve never needed this number of IPs before and wondered which is the best way to go about it?

Many thanks.
 
User avatar
dasiu
Trainer
Trainer
Posts: 232
Joined: Fri Jan 30, 2009 11:41 am
Location: Reading, UK
Contact:

Re: > 254 IPs

Fri Jan 06, 2012 4:21 am

192.168.0.0/23 will work normally, id doesn't differ from 192.168.0.0/24 - you will have 512 normal addresses :).
 
karlos
Frequent Visitor
Frequent Visitor
Posts: 81
Joined: Sun Jan 16, 2011 10:46 am

Re: > 254 IPs

Wed Jan 11, 2012 5:06 pm

/30 = 4IP
/29 = 8IP
/28 = 16IP
/27 = 32IP
/26 = 64IP
/25 = 128IP
/24 = 256IP
/23 = 512IP
/22 = 1024IP
/21 = 2048IP
/20 = 4096IP
....
but you cant use the borders so 0 and 255 are not ussable.

so always minus 2


so 192.168.0.1/23 will give you space for clients from 192.168.0.2 to 192.168.1.254 (192.168.0.0 border, 192.168.0.1 Gateway, 192.168.1.255 border)

Or you can also use 2 or more pools so you can use for your DHCP pool1 = 192.168.0.0/24 and second pool2 = 192.168.1.0/24 as the "next pool" and the DPHS will give at the first all adresses from pool1 and than from pool2.


If it helps you please give me carma
 
CCDKP
Member Candidate
Member Candidate
Posts: 170
Joined: Fri Jan 28, 2011 11:24 pm
Location: Midwest, United States

Re: > 254 IPs

Wed Jan 11, 2012 7:07 pm

Depending on how / what you are setting up, I would typically set:
/ip address
add address=192.168.0.1/23 disabled=no interface=<INTERFACE> network=192.168.0.0

/ip pool
add name=DHCP2 ranges=192.168.1.6-192.168.1.249
add name=DHCP1 next-pool=DHCP2 ranges=192.168.0.6-192.168.0.249

/ip dhcp-server
add address-pool=DHCP1 authoritative=yes bootp-support=static disabled=no interface=<INTERFACE> lease-time=1d name=DHCP

/ip dhcp-server network
add address=192.168.0.0/23 dns-server=192.168.0.1 gateway=192.168.0.1 netmask=23
While you could use a single large DHCP pool, I typically use multiple for two reasons:

1) I have run into some issues from time to time with poorly written clients choking on the .255 and .0 addresses in the middle, so I just avoid handing them out, even if they are technically valid.

2) I like to leave a 5 IP buffer on both sides of a pool, so I have static IP's reserved if I ever need them, and if for some reason I need to split them back into /24's, i don't have to rebuild as much, and keep things consistent. (i always know 1-5 and 250-254 are reserved)

Is it overkill? Probably. Has it worked great for me? Absolutely. Another thought, if this is for a network where you have a lot of turnover (public hotspots, schools, etc), try turning down the lease time to 6-8h and you will find you can stretch an address pool a lot further.
CC_DKP: MTCNA, MTCRE, MTCWE, MTCTCE, part-time packet wrangler

Who is online

Users browsing this forum: No registered users and 96 guests