Using RIP with Windows Clients
As your network grows and routing gets more complicated than just directly connected networks and one default route, using some method of centrally managing routing information becomes inevitable.
RIP (Routing Information Protocol) is one of the oldest and most widely supported protocols for distributing routing information in a (small) network. It's also a very simple protocol and support for it is also included in Microsoft's Windows (as the optional "RIP Listener Service"). Although Microsoft's documentation only mentions that RIP v1 is supported, at least Windows 2000/XP Professional is also able to receive RIP v2 broadcasts (and even multicasts).
So, the only thing you have to do is install the "RIP Listener Service" on all your Windows clients and install some RIP v2 server on your routers/gateways.
Why is RIP v1 not sufficient?
Well, it might be sufficient if you don't need CIDR (Classless InterDomain Routing) or VLSM (Variable-Length Subnet Masks). Interestingly, one of the major differences between RIP v1 and RIP v2 is that version 2 defines fields for a specifying a netmask and the next-hop which were already reserved (and required to be set to 0) in version 1 of the protocol (and I bet that they were reserved for just that reason).
Why not use DHCP?
Because DHCP, just like RIP v1, doesn't support netmasks which are necessary for CIDR/VLSM. Additionally, the Windows (at least XP Professional) DHCP client interprets a static route set via DHCP as a host-route, not as a net-route (with a default netmask).
Installing GNU Zebra on Linux
Because the documentation for GNU Zebra isn't always as clear as it could be, I provide some simple configuration examples here to start with.
/etc/zebra/zebra.conf:
hostname Router interface eth0 multicast interface eth1 multicast log file /var/log/zebra/zebra.log
/etc/zebra/ripd.conf:
hostname ripd router rip network eth0 network eth1 redistribute connected redistribute static log file /var/log/zebra/ripd.log
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