Date: Sun, 22 Jul 2007 19:30:08 GMT From: Dan Lukes <dan@obluda.cz> To: freebsd-bugs@FreeBSD.org Subject: Re: bin/111493: routed doesn't use multicasts for RIPv2 via P2P interfaces Message-ID: <200707221930.l6MJU8rX072015@freefall.freebsd.org>
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The following reply was made to PR bin/111493; it has been noted by GNATS.
From: Dan Lukes <dan@obluda.cz>
To: Vernon Schryver <vjs@calcite.rhyolite.com>
Cc: freebsd-gnats-submit@FreeBSD.org, bms@incunabulum.net,
carlson@workingcode.com
Subject: Re: bin/111493: routed doesn't use multicasts for RIPv2 via P2P interfaces
Date: Sun, 22 Jul 2007 21:24:57 +0200
Vernon Schryver napsal/wrote, On 07/21/07 15:45:
> If an interface is point-to-point (it sets the IFF_POINTOPOINT bit),
> is it right to send to the RIPv2 multicast address?
Why not ?
To send or not to send the multicast is question related to "is
supported or is not supported multicasting on interface". It isn't
related to question "is the interface of type X".
> Even on a GRE tunnel, why isn't it better to unicast to the router at
> the other end of the tunnel instead of multicasting?
'it is better' and 'it is right' is questions of wo different
categories. The answer for the first is "yes, there is no reason to
forbid multicast addresses on P2P interface when if network stack
support it". There is no reason to punish GRE users even if we don't
like the protocol personally.
The answer for the second is not simple. "Better" is subjective
category - I don't know the all details of all network specifications of
all networks.
If you trust the administrator to decide on ethernet interface, I see
no reason not to trust them on P2P interface as well.
> Consider the error of the missing () in the first change:
> + if (ifp->int_if_flags & IFF_POINTOPOINT && ! ifp->int_if_flags & IFF_MULTICAST) {
You are true.
> description of the failure with the current code.
The descripion "of the failuter" is simple. The administrator of other
side use not FreeBSD nor your routed. It's policy is - RIPv2 on
multicasts. The RIPv2 on unicasts are blocked by firewall. He says that
RIPv2 daemon on multicast link shall be able to use multicast, unless
it's implementation is incomplete.
I don't want dispute about it's mad policy decision. I dislike the GRE
tunnels as you.
Despite of it, there is no technical reason not to allow RIPv2
multicasting over a multicast capable interface, so the statement about
incomplete implementation seems to be true.
The required changes in the current code is simple, but the final
decision is yours.
Please note my knowledge of english language is far from perfect.
Dan
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