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Date:      Sun, 06 Jan 2008 22:41:04 +0100
From:      Andre Oppermann <andre@freebsd.org>
To:        Vadim Goncharov <vadim_nuclight@mail.ru>
Cc:        Qing Li <qingli@freebsd.org>, FreeBSD Net <freebsd-net@freebsd.org>, arch@freebsd.org, Ivo Vachkov <ivo.vachkov@gmail.com>, Robert Watson <rwatson@freebsd.org>, Julian Elischer <julian@elischer.org>, "Bruce M. Simpson" <bms@freebsd.org>
Subject:   Re: resend: multiple routing table roadmap (format fix)
Message-ID:  <47814AF0.9070509@freebsd.org>
In-Reply-To: <opt4i0rlz317d6mn@nuclight.avtf.net>
References:  <4772F123.5030303@elischer.org>	<f85d6aa70712261728h331eadb8p205d350dc7fb7f4c@mail.gmail.com>	<477416CC.4090906@elischer.org>	<opt4c0imk24fjv08@nuclight.avtf.net>	<477D2EF3.2060909@elischer.org>	<opt4g4kcis17d6mn@nuclight.avtf.net>	<4780E5E7.2070202@FreeBSD.org> <4781197F.1000105@elischer.org> <opt4i0rlz317d6mn@nuclight.avtf.net>

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Vadim Goncharov wrote:
> 07.01.08 @ 00:10 Julian Elischer wrote:
> 
> 
>>>> Is multicast and multipath routing the same?
>>>  No. They are currently orthogonal.
>>>  However it makes sense to merge the multicast and unicast forwarding 
>>> code as currently MROUTING is limited to a fan-out of 32 next-hops 
>>> only. In multicast, next-hops are normally just interfaces.
>>>  Also the IETF MANET ad-hoc IP is going to need hooks there; 
>>> multicast in MANET needs to address its next-hops by their unicast 
>>> address, and encapsulate the traffic with a header. This is not true 
>>> link layer multicast -- although it might use link layer multicast to 
>>> leverage the hash filters in 802.11 MACs.
>>>  As regards getting ARP out of forwarding tables, this should have 
>>> happened a long time ago...
>>
>> I'm not 100 % convinced of this...
>> I was, but I think there may still be a place for a cached arp pointer
>> in hte next hop route to the arp entry for that next hop.
>> I DO however thing that the arp stuff should nto be accessing its
>> data via the routing table.
> 
> Surely, routing table should contain a cached pointer to an entry in L2 
> table (ARP in case of Ethernet), to not do double lookups. But still 
> separate those tables...

Locking hell over again.  How do you remove an ARP entry without doing
a full walk over the entire routing table (some 250K entries for the
DFZ)?  Make it rmlocks and be done with it.

-- 
Andre




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