Subnetting Post: 302993570

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Special Forums IP Networking Subnetting Post 302993570 by drysdalk on Saturday 11th of March 2017 07:41:05 AM

03-11-2017

Registered User

Hi,

Firstly, from just looking at a single IP, you can't tell how large the network it's a part of is. You need to know the netmask. So for example, if I had an IP of 192.168.1.10, that doesn't tell you anything at all about how large or small the network I'm a part of is.

But if I tell you the netmask - e.g. 192.168.1.10/24 or 192.168.1.10/255.255.255.0 - then you know it's part of a network of 256 addresses, running from 192.168.1.0 to 192.168.1.255.

If on the other hand I'd told you the netmask was 192.168.1.10/25 or 192.168.1.10/255.255.255.128 - then you'd know it was part of a network of 128 addresses going from 192.168.1.0 to 192.168.1.127.

And again, in every network, the very first address and the very last address are not usable for hosts, as they are reserved for other purposes.

You can also get plenty of other netmasks than the old simple Class A, B, C notation tells you. For instance I could just have easily told you my netmask was 192.168.1.10/28, in which case you'd then be able to calculate that the network I was a part of runs from 192.168.1.0 to 192.168.1.15, and conists of 16 IP addresses.

So just from looking at an IP you can't tell anything about the size of the network. And these days, there are far more netmasks and subnet sizes that are far more common than the old Class A/B/C notation.

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LEARN ABOUT DEBIAN

vde_l3

VDE_L3(1)						      General Commands Manual							 VDE_L3(1)

NAME

       vde_l3 - Virtual Distributed Ethernet 'Layer 3' Switch.

SYNOPSIS

       vde_l3 -v vde_plug:ipaddress/netmask [-v...]  [-r target_network/netmask:gateway] [-G default_gw] [-M mgmt_socket]

DESCRIPTION

       A vde_l3 connects to one or more vde_switches, performing ip forwarding among its virtual interfaces. A new interface is created at startup
       for each -v option given at command line. Static routes to target networks can be defined using the -r option.

       vde_l3 -v /var/run/s1.ctl:192.168.0.1/24

       connects to the vde sock at /var/run/s1.ctl with its virtual interface ve0, having the address 192.168.0.1 and netmask 255.255.255.0.

       vde_l3 

       -v /var/run/s1.ctl:192.168.0.1/24 

       -v /var/run/s2.ctl:10.0.0.254/255.255.0.0

       connects to the two vde socks, with its virtual interfaces ve0 and ve1, having addressess 192.168.1.0 and 10.0.0.254 respectively. Hosts in
       each network can specify the vde_l3 as their gateway to reach the other one.

OPTIONS

       -v vde_plug:ipaddress/netmask
	      Creates a virtual network interfaces on the vde_l3 box, with address ipaddress and netmask netmask. Please note that the netmask can
	      be specified either in the 'classic' A.B.C.D mode, or just by giving the number of leading bits (f.e., /17 for 255.255.128.0).   One
	      can define as many interfaces as she wants.

       -r target_network/netmask:gateway
	      Specify  a static route through gateway to reach hosts in target_network with netmask netmask.  One can define as many routes as she
	      wants.

       -G default_gw
	      Specify a default gateway, to be used whenever no static route is defined for a target host.

       -M mgmt_socket
	      the unix socket where the parameters (interfaces addresses, routes, etc.) can be checked and changed  runtime.  unixterm(1)  can	be
	      used as a remote terminal for wirefilter.

NOTICE

       Virtual	Distributed  Ethernet is not related in any way with www.vde.com ("Verband der Elektrotechnik, Elektronik und Informationstechnik"
       i.e. the German "Association for Electrical, Electronic & Information Technologies").

SEE ALSO

       vde_switch(1), vdeq(1), unixterm(1), vde_cryptcab(1), wirefilter(1).

AUTHORS

       VDE_L3 is a tool by Daniele Lacamera <root@danielinux.net>

       VDE is a project by Renzo Davoli <renzo@cs.unibo.it>

Virtual Distributed Ethernet					    May 7, 2007 							 VDE_L3(1)

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vde_l3