Package: debian-reference-en
Version: CVS HEAD
Severity: wishlist
Tags: patch

Patch describes how to control which IP address is used
as the source IP for locally initiated traffic.
This is an issue when virtual interfaces are
assigned IP addresses on the same subnet,
as might be needed for certain kinds of
virtual hosting.

-- System Information:
Debian Release: 3.1
Architecture: i386 (i686)
Kernel: Linux 2.6.8-4-686-smp
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
--- gateway.sgml.orig	2007-07-25 11:15:48.026617484 -0500
+++ gateway.sgml	2007-07-25 11:31:07.158181829 -0500
@@ -960,7 +960,8 @@
 <sect2 id="high-virtual">Configuring virtual interfaces
 <p>
 Using virtual interfaces you can configure a single Ethernet card
-to be an interface to several IP subnetworks.
+with multiple IP address.  Usually the purpose is to connect the
+interface to several IP subnetworks.
 For example, suppose your host is on LAN network 192.168.0.x/24.
 You want to connect the host to the Internet using a public IP address
 provided via DHCP using your existing Ethernet card.
@@ -977,6 +978,12 @@
 </example>
 The interface <tt>eth0:0</tt> is a virtual interface.
 When it is brought up, so will its parent <tt>eth0</tt>.
+<p>
+when assigning multiple IP numbers belonging to a single subnet to one
+physical interface, the <tt>metric</tt> option may be used to control
+which of the IP numbers is used as the source address for locally
+initiated IP traffic.  The IP number of the active interface with the
+lowest <tt>metric</tt> becomes the originating IP.
 
 <sect1 id="net-reconf">High level network configuration using <package>ifupdown</package> logical interface definitions
 <p>

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