[Devel] Why use FAKEGATEWAY{,NET} instead of default dev venet0?

[Denis V. Lunev]

On Tue, 2008-10-14 at 14:15 +0400, Peter Volkov wrote:
> В Втр, 14/10/2008 в 11:51 +0400, Denis V. Lunev пишет:
> > On Fri, 2008-09-12 at 13:08 +0400, Peter Volkov wrote:
> > > venet0 is peer-to-peer device. Why openvz scripts
> > > set some $FAKEGATEWAYNET network on p2p device and then put nonexistent
> > > $FAKEGATEWAY as a gateway there? Seems that it's much more simple and
> > > clean way to setup networking is:
> > > 
> > > # route add default dev venet0
> > > or 
> > > # ip route add default dev venet0
> > > 
> > > Are there any drawbacks of this solution? I'm going to modify
> > > gentoo-{add,del}_ip.sh scripts but is it good idea?
> 
> > The answer is quite simple. Without a gateway you'll have a neighbour
> > entry for each incoming/outgoing destination.
> 
> Hm, where? On HN or VE, and how is this simple answer possible? In any
> case I did some investigations and I do not see any behavior change in
> neighbour aspect.
> 
> VE with nginx server running. I've opened some pages to be sure that at
> least some users are using this VE at this moment:
> 
> nginx ~ # ip addr
> 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue
>     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
>     inet 127.0.0.1/8 scope host lo
> 3: venet0: <BROADCAST,POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1500 qdisc
> noqueue
>     link/void
>     inet 172.16.0.41/32 scope global venet0
> 
> nginx ~ # ip route
> 127.0.0.0/8 via 127.0.0.1 dev lo
> default dev venet0  scope link  metric 2
> 
> nginx ~ # ip neigh show nud all
> 0.0.0.0 dev venet0 lladdr  NOARP
> 0.0.0.0 dev lo lladdr 00:00:00:00:00:00 NOARP
> 
> VE with old setup (with FAKEGATEWAY) and dns running (lot's of users
> connected) has exactly same neighbour table.
> 
> At home node there is neighbour entry and I see both clients from
> connected to nginx and dns there. So sorry, I don't understood simple
> answer. Could you, please, elaborate a little bit more? Thanks.

hmmm.... This seems interesting. The purpose of this route was exactly I
have sad. If you are right, this is legacy crap.

Thank you for pointing this out. I'll will look into this deeply. If you
want to speed-up vzctl change - bugzilla entry would be of great help.

Regards,
	Den