Re: Help Broadcasting a UDP packet on the LAN:URGENT
From: Charles Swiger (cswiger_at_mac.com)
Date: 10/23/03
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Date: Thu, 23 Oct 2003 14:23:57 -0400 To: net@freebsd.org
On Thursday, October 23, 2003, at 11:52 AM, Barney Wolff wrote:
> On Thu, Oct 23, 2003 at 01:55:55AM -0700, Wes Peters wrote:
[ ... ]
> What are you going to do when IPv6 comes into more general use, since
> it has no broadcast address?
Are you asking what a IPv4-to-IPv6 translator (like gif?) should do, or
are you worried about the case of a machine configured for IPv6 only
and not for IPv4? I expect that most people will be using IPv4 for
quite some time; we don't have to do something for the IPv6-only case
to still have this be useful.
>> Interactions with VLANs, for instance. If you send an
>> all-ones broadcast on an interface that has one or more VLANs
>> configured,
>> do you repeat them "on" each VLAN as well? Ugh. What about
>> point-to-point links? Are those always considered gateways to a
>> foreign
>> network, or just another form of locally attached network?
>
> The multicast notion would suggest that this be handled as a special
> case of multicast, with a pseudo group that can't occur naturally.
> That way you get "for free" to control which interfaces should send
> the broadcast, based on group membership.
Multicast and broadcast addressing are working at layer-3, but the
point of using VLAN tags is to create logically 'seperate' networks
where the flow of traffic is being handled/segregated at layer-2 rather
than layer-3.
> The whole VLAN thing is nasty, but I'd say that the general issue is
> does the box itself have a virtual interface on the VLAN, or is it
> merely switching on it. If the former, you send packets and process
> received packets up the stack. If the latter, you just do what any
> switch/bridge would do, because "you" (ie, higher layers) are not
> really
> on that layer-3 network.
The all-ones broadcast is supposed to go to all physically connected
network segments, regardless of whether a particular interface is
ifconfig'ured with an IP that is part of a particular layer-3 subnet.
You should be able to send the broadcast packet out from an interface
which is up but does not have an IPv4 address assigned, right?
-- -Chuck _______________________________________________ freebsd-net@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org"
- Previous message: Christopher Schulte: "IPFW + BRIDGE: network capacity question"
- In reply to: Barney Wolff: "Re: Help Broadcasting a UDP packet on the LAN:URGENT"
- Next in thread: Wes Peters: "Re: Help Broadcasting a UDP packet on the LAN:URGENT"
- Reply: Wes Peters: "Re: Help Broadcasting a UDP packet on the LAN:URGENT"
- Reply: Barney Wolff: "Re: Help Broadcasting a UDP packet on the LAN:URGENT"
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