I’m a bit stuck and hoping someone can assist. I have 2 ISP connections. One of those ISPs I use only to route voice traffic (i.e. anything marked DSCP CS3 or EF). I was using static routes for a while, but my carrier seems to have just added many new IPs and ranges, so this is not manageable any more.
I used to run Vyatta community, and I had a script that would mark packets with DSCP 24 (CS3) or 46 (EF). It used the PREROUTING table for this. Then Vyatta would route based on the mark. Unfortunately I lost the script, and I can’t seem to make this work in VyOS 1.1.5.
here’s an example of what I’m using to mark packets:
iptables -I PREROUTING -i eth0.10 -t mangle -m dscp --dscp 46 -j MARK --set-mark 20
It appears to be marking the packets:
root@vyatta:~# iptables -vt mangle -L PREROUTING
Chain PREROUTING (policy ACCEPT 7299K packets, 6515M bytes)
pkts bytes target prot opt in out source destination
114 43227 MARK all -- eth0.10 any anywhere anywhere DSCP match 0x18 MARK set 0x14
Now where I am stuck is how to set the next hop of marked packets to my second ISP? I don’t see any way to do policy routing based directly off of DSCP. I tried configuring a route-map that sets the next-hop based on tag, but it doesn’t appear to do anything.
Can anyone help?
EDIT: FOUND THE SOLUTION
The tip about a second route table was the key. I modified my script somewhat and it’s working.
Here’s a simplified version of what I did:
#!/bin/bash # flush the PREROUTING mangle table iptables -t mangle -F PREROUTING # mark packets with DSCP set to CS3 or EF iptables -I PREROUTING -i eth0 -t mangle -m dscp --dscp 46 -j MARK --set-mark 20 iptables -I PREROUTING -i eth0 -t mangle -m dscp --dscp 24 -j MARK --set-mark 20 iptables -I PREROUTING -i eth1 -t mangle -m dscp --dscp 46 -j MARK --set-mark 20 iptables -I PREROUTING -i eth1 -t mangle -m dscp --dscp 24 -j MARK --set-mark 20 ip route flush table 2 ip route add default via 67.x.x.x dev eth2 table 2 ip route add 127.0.0.0/8 dev lo table 2 ip route add 10.x.2.0/24 dev eth0 table 2 ip route add 10.x.5.0 dev eth1 table 2 ip route add 67.x.x.0/24 dev eth2 table 2 ip route flush cache ip rule flush ip rule add from all table main priority 32766 ip rule add fwmark 20 table 2 priority 1000