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qwertysqwerty
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Joined: Sun Mar 30, 2014 12:43 am

Two default routes - DAC, DS.

Sun Nov 02, 2014 9:00 pm

I have an error in my routing table. Let me explain my home set-up:
  • I use an ADSL/ADSL2+ modem. This modem is connected to ether1-gateway port of my [http://routerboard.com/]RB2011UiAS-2HnD-IN router.
  • My RB2011UiAS-2HnD-IN obtains a LAN IP from the DHCP server configured on the modem (192.168.2.0/24).
  • My RB2011UiAS-2HnD-IN uses the PPPoE client to obtain a WAN IP from my ISP via the ADSL/ADSL2+ modem.
The problem is that the RB2011* will end up with two default gateway addresses in the routing table after it has obtained the WAN IP from my ISP.

For example:
 #      DST-ADDRESS        PREF-SRC        GATEWAY            DISTANCE
 0 ADS  0.0.0.0/0                          [ISP_REMOTE_IP]           1
 1  DS  0.0.0.0/0                          192.168.2.1               1
...
 3 ADC  [ISP_REMOTE_IP]/32 [MY_WAN_IP]     pppoe-out1                0
 4 ADC  192.168.2.0/24     192.168.2.10    ether1-gateway            0
 5 ADC  192.168.10.0/24    192.168.10.1    wlan1                     0
...
This is a problem because:
  • increased latency (?) / route duplication
  • the direct static (DS) default route is highlighted blue (in WinBox GUI) and I have no idea what this means
  • I have to remove this route manually each time my WAN IP changes
 
jarda
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Re: Two default routes - DAC, DS.

Mon Nov 03, 2014 8:32 am

Blue lines are inactive so they have no influence on routing decision. Only active routes do.
 
Rudios
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Posts: 966
Joined: Mon Mar 11, 2013 12:58 pm
Location: The Netherlands

Re: Two default routes - DAC, DS.

Mon Nov 03, 2014 8:59 am

I have an error in my routing table. Let me explain my home set-up:
  • I use an ADSL/ADSL2+ modem. This modem is connected to ether1-gateway port of my [http://routerboard.com/]RB2011UiAS-2HnD-IN router.
  • My RB2011UiAS-2HnD-IN obtains a LAN IP from the DHCP server configured on the modem (192.168.2.0/24).
  • My RB2011UiAS-2HnD-IN uses the PPPoE client to obtain a WAN IP from my ISP via the ADSL/ADSL2+ modem.
The problem is that the RB2011* will end up with two default gateway addresses in the routing table after it has obtained the WAN IP from my ISP.

For example:
 #      DST-ADDRESS        PREF-SRC        GATEWAY            DISTANCE
 0 ADS  0.0.0.0/0                          [ISP_REMOTE_IP]           1
 1  DS  0.0.0.0/0                          192.168.2.1               1
...
 3 ADC  [ISP_REMOTE_IP]/32 [MY_WAN_IP]     pppoe-out1                0
 4 ADC  192.168.2.0/24     192.168.2.10    ether1-gateway            0
 5 ADC  192.168.10.0/24    192.168.10.1    wlan1                     0
...
This is a problem because:
  • increased latency (?) / route duplication
  • the direct static (DS) default route is highlighted blue (in WinBox GUI) and I have no idea what this means
  • I have to remove this route manually each time my WAN IP changes
You do not need a DCHP client address from your modem, I guess. I assume it is only needed for maintenance tasks on the modem.
Because you have a pppoe client I assume your modem is in bridge mode.
Testing setup with: 2 x RB750UP | 2 x RB750GL | 1 x RB951G-2HnD | 1 x RB2011UiAS-IN
 
qwertysqwerty
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Posts: 24
Joined: Sun Mar 30, 2014 12:43 am

Re: Two default routes - DAC, DS.

Mon Nov 03, 2014 7:31 pm

Blue lines are inactive so they have no influence on routing decision. Only active routes do.
Ah I see. Good.
You do not need a DCHP client address from your modem... I assume it is only needed for maintenance tasks on the modem.
Yes, I do need it. For firmware updates, etc. It is useful to have this connectivity to the modem.
Because you have a pppoe client I assume your modem is in bridge mode.
Yes. What value does this comment add?
 
Rudios
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Posts: 966
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Location: The Netherlands

Re: Two default routes - DAC, DS.

Tue Nov 04, 2014 10:24 am

Blue lines are inactive so they have no influence on routing decision. Only active routes do.
Ah I see. Good.
You do not need a DCHP client address from your modem... I assume it is only needed for maintenance tasks on the modem.
Yes, I do need it. For firmware updates, etc. It is useful to have this connectivity to the modem.
Because you have a pppoe client I assume your modem is in bridge mode.
Yes. What value does this comment add?

If you need connection to your modem only for firmware upgrades, I would disable the DHCP client on the MikroTik and only enable it when communication to the modem is needed in any certain time.
Another solution would be to put a static IP address on the interface connected to the modem, this won't get you a default route.
Also disabling the "add default route" option on the DCHP client could be an option. Since the IP addresses of your modem and mikrotik are in the same segment, a router is not needed for communication to the modem.
Testing setup with: 2 x RB750UP | 2 x RB750GL | 1 x RB951G-2HnD | 1 x RB2011UiAS-IN
 
jarda
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Joined: Mon Oct 22, 2012 4:46 pm

Re: Two default routes - DAC, DS.

Tue Nov 04, 2014 10:38 am

I have cable modem in transparent mode and mikrotik router with DHCP client on wan interface. When modem and router both start simultaneously the router is faster and asks for ip. As the modem is not linked yet to cable provider it provides local address by his own. When the link to operator goes up, it sends nak and router asks again. Now it gets public ip. As the modem still keeps his ip and it is from other subnet I use locally the default route routes all packets with modem destination ip to the wan and modem normally responds even the wan port has public ip yet. So no other rule for that is necessary.
 
Rudios
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Joined: Mon Mar 11, 2013 12:58 pm
Location: The Netherlands

Re: Two default routes - DAC, DS.

Tue Nov 04, 2014 3:09 pm

I have cable modem in transparent mode and mikrotik router with DHCP client on wan interface. When modem and router both start simultaneously the router is faster and asks for ip. As the modem is not linked yet to cable provider it provides local address by his own. When the link to operator goes up, it sends nak and router asks again. Now it gets public ip. As the modem still keeps his ip and it is from other subnet I use locally the default route routes all packets with modem destination ip to the wan and modem normally responds even the wan port has public ip yet. So no other rule for that is necessary.
In my case, this works the same. I first get a 192.168.x.x address from the modem and when the link to ISP is online, my mikrotik gets my public IP (and looses it local 192.168.x.x address)
But since qwertysqwerty is using pppoe (ADSL) he has 2 dhcp-client running. (I assume)
Testing setup with: 2 x RB750UP | 2 x RB750GL | 1 x RB951G-2HnD | 1 x RB2011UiAS-IN

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