Re: [mpls-linux-general] Looking for examples to test TC/DS/IPTABLE

[Olivier D. <Oli...@rd...>]

Hi Jim,

James R. Leu wrote:

> I see the light now.....
> 
> Last night I dug around the kernel and I now see why you think that
> netfilter is the best way for interacting with the ipv4 routing table.
> I will look more at your work and see how I can make it less MPLS specific.
> 
> Right now I think I am going to add a new netlink.  POST_ROUTING_SLOW.
> This will allow a netlink to modify the route cache entry.  The result will
> be that the netlink code for this will only be run for the first packet
> in the "flow".    The rest will hit the entry in the route cache and
> will be redirected to the MPLS layer.
> 


Ok, i think it's a good way setup the process of the first packet. It's 
that we do by hacking the rt_set_nexthop code. This function is call 
only for the first packet of a flow (ie. the first ping packet). Then, 
the entry are kept into the route cash a moment (so, stoping a ping and 
start some time after a second ping, doesn't call another time 
rt_set_nexthop because the route cash entry is still valid).

What do you intend to do with this new POST_ROUTING_SLOW netlink ?
- directly setup the route cash entry or
- setup mpls_index (or nfmark) ?


> Will this satisfy your hope of avoiding double lookups (for every packet
> except the first)?


Yes.

Olivier
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