ip route add default scope global nexthop dev ppp0 nexthop dev ppp1		
		

neo@debian:~$ sudo ip route add default scope global nexthop via 192.168.3.1 dev eth0 weight 1 \
nexthop via 192.168.5.1 dev eth2 weight 1
	
neo@debian:~$ sudo ip route
192.168.5.0/24 dev eth1  proto kernel  scope link  src 192.168.5.9
192.168.4.0/24 dev eth0  proto kernel  scope link  src 192.168.4.9
192.168.3.0/24 dev eth0  proto kernel  scope link  src 192.168.3.9
172.16.0.0/24 dev eth2  proto kernel  scope link  src 172.16.0.254
default
        nexthop via 192.168.3.1  dev eth0 weight 1
        nexthop via 192.168.5.1  dev eth1 weight 1

		

ip route add default scope global nexthop via $P1 dev $IF1 weight 1 \
nexthop via $P2 dev $IF2 weight 1