Gentoo Archives: gentoo-user

From: Dale <rdalek1967@×××××.com>
To: gentoo-user@l.g.o
Subject: Re: [gentoo-user] Linksys router BEFSR41 loosing internet
Date: Mon, 20 Dec 2010 09:39:24
Message-Id: 4D0F23EC.50006@gmail.com
In Reply to: Re: [gentoo-user] Linksys router BEFSR41 loosing internet by Stroller
1 Stroller wrote:
2 > Sounds like you're getting it.
3 >
4 > A computer (this includes routers) cannot have two interfaces on the same subnet. They can have multiple network interfaces, as long as they're all on different subnets. A router is a computer with multiple network interfaces, acting to gateway data between those subnets.
5 >
6 > Whether the machines are on the same subnet is determined by the "subnet mask". If the subnet mask is 255.255.0.0 then only the first two bytes of the IP address need to be the same for the computers to be on the same subnet. I.E. 192.168.1.1 and 192.168.2.3 would be on the same subnet if they had the mask of 255.255.0.0.
7 >
8 > But a subnet mask of 255.255.255.0 means that the first 3 bytes need to be the same for them to be on the same subnet - so 192.168.1.1 would be on the same subnet as 192.168.1.2, but not on the same subnet as 192.168.2.3, 192.168.2.4, 192.168.3.3, or 192.168.44.8.
9 >
10 > IP addresses and subnet masks can be written more succinctly using the "/" notation. "/16" means "255.255.0.0", "/24" means "255.255.255.0". So 192.168.2.3/16 means "IP address 192.168.2.3, subnet mask 255.255.0.0" whereas 192.168.2.3/24 means "IP address 192.168.2.3, subnet mask 255.255.255.0". Ranges are sometimes written 192.168.1.100-200, but don't do that when you're talking about a whole subnet (1-255) because it just looks odd. Use the slash notation instead, or just say "192.168.1.x and 192.168.2.y". So this email is to say that I don't know what you're doing writing with a ">". :P
11 >
12 > On these networks the final .255 address (eg. 192.168.1.255) is reserved for broadcast use, and you cannot allocate it to your PCs. Addresses ending in a .1 (e.g. 192.168.0.1) tend generally to be used for the subnet's gateway (the router).
13 >
14 > When a computer wants to send a packet to a computer on a different subnet it send it to the router instead (set in its configuration as the "gateway" to the network, typically the default gateway) with the instructions "hi, please forward this to ...".
15 >
16 > Stroller.
17 >
18 >
19
20 I'm kind of getting it. I read up on netmask and sort of get it but it
21 is still murky. Basically for my little wimpy network, 255.255.255.0
22 will suite all my needs. I think.
23
24 I set it up like this. The modem uses DHCP to get the IP from AT&T. My
25 local IP from the modem is 192.168.1.2. Then the router has the IP
26 192.168.2.1 for my connection to the puter. The IP of my puter is
27 192.168.2.5. The next puter will be 192.168.2.6 or something different
28 anyway.
29
30 Basically the modem has its network and the router has its network for
31 the LAN. Another thing I like, I can access the router and modem if
32 needed. I guess 100 for the last number would work too.
33
34 I need to read up on the netmask thing some more. It's still murky for
35 sure.
36
37 How's it look? Think it will work for a while?
38
39 Dale
40
41 :-) :-)

Replies

Subject Author
Re: [gentoo-user] Linksys router BEFSR41 loosing internet Peter Humphrey <peter@××××××××××××××.org>