veth, macvlan or maybe sth else?

Well this interesting, I'm playing with a vserver and I do not really understand how it works with eth and dummy.

Whatever, in your case, I think you need to enable ip forwarding.

sysctl -w net.ipv4.conf.all.forwarding=1

Check /etc/sysctl.conf to make it permanent

Naming interface that come into the bridge is a good idea if you want to know who is who. In the lxc config file:

lxc.network.veth.pair=eth0-guest1

network in lxc allow more sophisticated networking. For example, you could simulate a real "proxy" with 2 virtual interface, one on a bridge (say br0) connected to internet (public IPs, dmz, whatever) another (say br1) connected to the "internal services"

 .-----------.
 | host eth0 |<----.
 '-----------'     |
         .-------------------.                  .-------------------.
         | br0 (public IP)   |                  | br1 (10.1.1.1/24) |
         '-------------------'                  '-------------------'
                   ^            .--------------------.    ^
                   '------------|    guest squid     |----|
                                '--------------------'    |
                                     .---------------.    |
                                     | guest apache1 |----'
                                     '---------------'    |
                                     .---------------.    |
                                     | guest apache2 |----'
                                     '---------------'    |
                                                 .----------------.
                                                 | guest database |
                                                 '----------------'

Note: for a second virtual ethernet interface, just repeat the lxc.network... stanza

Got the same problem. I was trying to forward ports to lxc container with

iptables -t nat -A PREROUTING -p tcp -m tcp --dport 7070 -j DNAT --to-destination 172.16.110.15:7070

But it doesn't work. The solution was really simple:

iptables -t nat -A POSTROUTING -o br0 -j MASQUERADE

For more details look at this