[Freeciv-Dev] Re: (PR#6707) Announce server on LAN

["John Bauman" <john@xxxxxxxxxxxxxxxx>]

----- Original Message ----- 
From: "Raimar Falke" <i-freeciv-lists@xxxxxxxxxxxxx>
To: <andrearo@xxxxxxxxxxxx>
Sent: Monday, November 03, 2003 11:25 AM
Subject: [Freeciv-Dev] Re: (PR#6707) Announce server on LAN

> > As a user you don't have to setup anything. The application layer
> > software in the client and server tells the kernel to give it
> > packets from the multicast group.  I found this useful:
> > http://www.tldp.org/HOWTO/Multicast-HOWTO-2.html
>
> Looking at this and pinging around on some systems I got responses
> when I ping 224.0.0.1 but no answer when I used 225.0.0.1. This is
> logical from the above URL:
>
>    224.0.0.1 is the all-hosts group. If you ping that group, all
>    multicast capable hosts on the network should answer, as every
>    multicast capable host must join that group at start-up on all it's
>    multicast capable interfaces.
>
> This means that none of the other hosts which answered to 224.0.0.1
> are part of 225.0.0.1.
>
> In addition the URL states:
>
>    In any case, range 224.0.0.0 through 224.0.0.255 is reserved for
>    local purposes (as administrative and maintenance tasks) and
>    datagrams destined to them are never forwarded by multicast
>    routers.
>
> So if we choose 224.0.0.1 we know that all hosts are on this group AND
> we know that the TTL is irrelevant since the packets are routed.
Why do you want to use an address that all hosts are on? Wouldn't it be
better if only the hosts that cared got messages (as small as they may be)?
>
> The only problem I see is that the server is behind a router. So how
> do you define LAN?
>
> If all this is correct I'm favoring as the default a scan in 224.0.0.1
> with no special TTL and (optionally if you want to code it) "an export
> mode" where you can input a special multicast group and optionally a
> TTL.
>
> Raimar
>
> -- 
>  email: rf13@xxxxxxxxxxxxxxxxx
>   One nuclear bomb can ruin your whole day.
>
>
>