DrayTek UK Users' Community Forum

Help, Advice and Solutions from DrayTek Users

WAN IP Alias breaks inter-lan routing.

More
06 Jul 2015 17:32 #83817 by bento
Hi all,

I have a Draytek 2830 setup with 3 x Subnets on Port based VLAN as follows

1.) 10.0.11.0/24
2.) 172.23.136.0/24
3.) 10.44.156.0/22

We have a x.x.x.134/29 IP Block from our ISP and we're using x.x.x.134 as the main Router IP and for NAT from subnet 1, I've assigned IP x.x.x.133 as a WAN Alias and we're using this as the IP for NAT on subnet 2. (subnet 3 does not use the draytek as it's default gateway, it's just on the network to allow routing between an organisation in the same building, traffic from this subnet to the WAN is blocked).

When setting the above up using the route policies in the menu - Inter-LAN routing between subnets 1 and 2 breaks and I'm not sure why. (I've not tested between 2 and 3, and routing between 1 and 3 is not needed).

On investigating, running a ping/traceroute from subnet 2 to subnet 1 fails with a reply from our upstream ISP gateway (x.x.x.67), so the Draytek is routing these packets to the upstream gateway and I'm not sure why. The routing table looks correct to me:

Key: C - connected, S - static, R - RIP, * - default, ~ - private
* 0.0.0.0/ 0.0.0.0 via x.x.x.67 WAN1
C~ 10.0.11.0/ 255.255.255.0 directly connected LAN1
C~ 10.44.156.0/ 255.255.252.0 directly connected LAN3
* x.x.x.67/ 255.255.255.255 via x.x.x.67 WAN1
S x.x.x.134/ 255.255.255.255 via x.x.x.134 WAN1
C~ 172.23.136.0/ 255.255.255.0 directly connected LAN2

Any help is greatly appreciated, thanks.

Please Log in or Create an account to join the conversation.

Moderators: ChrisSami