netdev - Re: Regarding Routing cache

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Message-ID: <1321511214.3274.25.camel@edumazet-laptop>
Date:	Thu, 17 Nov 2011 07:26:54 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Ajith Adapa <adapa.ajith@...il.com>
Cc:	netdev@...r.kernel.org
Subject: Re: Regarding Routing cache

Please dont top post on netdev

Le jeudi 17 novembre 2011 à 11:34 +0530, Ajith Adapa a écrit :
> Hi,
> 
> Actually I have doubt with IPv6 related packets.
> 
> In case of IPv6 packet in ip6_route_output function is called for
> destination related information.
> where ip6_route_output calls "fib6_rule_lookup" function. Why lookup
> is done in fib table instead of routing cache in case of IPv6 packet ?
> 
> In case of IPv4 packet ... ip_route_output checks in routing cache and
> if there is a cache miss then it checks the fib table.
> 

IPv6 has no routing cache, and wont have one, since we are trying to
remove IPv4 routing cache :)

> 
> 
> 
> On Thu, Nov 17, 2011 at 10:30 AM, Ajith Adapa <adapa.ajith@...il.com> wrote:
> > Hi,
> >
> > I have a small doubt regarding routing cache in linux kernel.
> >
> > It seems ip_route_connect is the way we have to access routing cache
> > entries. In case of all locally generated packets I see that struct
> > dst_entry is filled up with a lookup in routing cache.
> >
> > What about in case of forwarding packets ? I dont see any usage of
> > routing cache mechanism to fill up the struct dst_entry. So it seems
> > we directly check the fib_rules or fib table to fill the structure.
> > If it is true then it would be very slow right ?
> >
> > Sorry if I am wrong about above findings. Do correct me if I am wrong about it ?
> >
> > Regards,
> > Ajith
> >
> --

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