Getting desperate...

RouterOS General
1

I am trying to replace a combined router and ADSL modem (Draytek Vigor 2600) with a seperate modem (D-Link DSL-300T) and Mikrotik. I’ve been trying for a few days now and I’m starting to get desperate!

I have tried to copy the configuration from the Draytek which looks like this:

Key: C - connected, S - static, R - RIP, * - default, ~ - private

  •              0.0.0.0/  0.0.0.0               via 62.3.83.3, IF3

C X.X.X.240/ 255.255.255.248 is directly connected, IF0
C~ 192.168.50.0/ 255.255.255.0 is directly connected, IF0

(IF0 = LAN port, IF3= WAN port)

Interface 0 Ethernet: Status: UP
IP Address: 192.168.50.1 Netmask: 0xFFFFFF00 (Private) (/24)
IP Address: X.X.X.246 Netmask: 0xFFFFFFF8 (/29)
MAC: 00-50-7F-22-D4-8D

Interface 3 PPPoE: Status: UP
IP Address: X.X.X.246 Netmask: 0xFFFFFFFF (/32)
MAC: 00-50-7F-22-D4-8E

My assigned public address range is X.X.X.240-247. My ISP tells me that 62.3.83.3 is their ADSL gateway. I have set up addresses on the mikrotik like this:

[admin@pad001X] ip address> print
Flags: X - disabled, I - invalid, D - dynamic

ADDRESS NETWORK BROADCAST INTERFACE

0 192.168.0.1/24 192.168.0.0 192.168.0.255 private
1 X.X.X.246/29 X.X.X.240 X.X.X.247 private
2 X.X.X.246/32 X.X.X.246 X.X.X.246 public

When I add a default route, MT assigns it to the private interface:

[admin@pad001X] ip route> print
Flags: X - disabled, I - invalid, D - dynamic, J - rejected,
C - connect, S - static, r - rip, o - ospf, b - bgp

DST-ADDRESS G GATEWAY DISTANCE INTERFACE

0 S 0.0.0.0/0 r X.X.X.246 1 private
1 DC 192.168.0.0/24 r 0.0.0.0 0 private
2 DC X.X.X.240/29 r 0.0.0.0 0 private

So, of course, no routing takes place. I also tried setting up a DHCP client on the public interface with “add default route” enabled, but MT shows the route as invalid. How can I get this setup to work?

Any advice appreciated.
Guy

2

I think the first mistake you have is to set up the same IP address at both the interface (82.68.122.246)

I could setup 86.68.122.241/32 to the public and 86.68.122.246/29 to the private

Doing this should solve your problem. But you have a very bad modem. Infact DSL-300T is a very bad product. Upgrade to last firmware some bugs has bin fixed, not all!

3

I think I have already tried this setup, but I’m not sure so will try again tonight.

Can you describe what the problems are with the 300T and a good alternative modem?

Thanks,
Guy

4

don’t forget to add this to the routing table:

destination gateway interface
86.68.122.240/29 86.68.122.241 public


So your network will be reachble from internet.

5

No, this doesn’t work. When I try to assign the gateway, the router selects the private interface. Also, the gateway, I believe, should be a reachable router available on a directly connected network. So, I cannot put one of my public subnet addresses on the public interface.

In other words, if one of the router’s interface’s address is XXX.241, and the gateway is XXX.241, the packet’s journey is over when it reaches the interface. It needs at least another hop to get anywhere.

I’m beginning to think there is some basic incompatibility between the modem and RouterOS.

6

When you set up the dhcp on the public what address did you get?

The dsl-300T pass only 255.255.255.255 (single host) subenet.

So may be you have to write your own routing entry without relaying to dynamic connection.

Then try to have a working configuration using private address on private interface.
Then try to route the subnet you have on the private. May be proxy-arp should be set on the public interface.