ECMP Support

[Li, Qing]

> 
>   My idea is use ECMP on 7.x branch to balance 100Mbit 
> Lan-2-Lan links between our enterprise network and IDC network.
> 

	I can merge those changes into 7.x. Frankly I have lost
	track of the release schedule so I do need to talk
	to the FreeBSD release team to figure out where and
	when I should integrate the code.

> 
> In this case the route table only change when a link goes 
> down, so I will remove this from routing table until this 
> goes up again. This is a problem with current ECMP implementation ?
> 

	The route selection uses a hash and because the number of route 
	entries changes when you remove that route from the routing
table,
	and depending on the hash key, you may get a different route 
	entry.

	In earlier 5.x releases when "inp_route" is present (route
	is sticky), tcp_output() provides that value and route
	lookup is bypassed.
	
	This is something we are working on for a fix in -current.

> >
> > The "route" and "netstat" commands work with ECMP. 
> > There isn't much documentation but I do intend to update the 
> > manpages soon.
> > Please indicate if there is any other command that you need.
> 
> I think this is enough for me.
> 

	Okay.

	-- Qing