Default gateway routing problem

Installing and Using OpenWrt Network and Wireless Configuration
1

Hello,

I have a quite simple network setup: an ISP gateway and 2 openwrt Archer C7 version 2 routers, which I use as simple access points. I disabled the WAN interface and bridged the Ethernet and Wireless interfaces.
One of the 2 openwrt access routers shows some strange behaviour. When I reset this access point, the ISP gateway becomes unreachable for all the devices in the LAN. I can reach all devices within the LAN itself, except the default gateway. I tried a lot but nothing seems to help. Does anybody have a clue?

I use the latest snapshot ath79 builds, but I also experienced this problem in the stable 17 and 18 builds.

2

How are the two connected together?

3

Via a set of regular switches (Dlink and a whitelabel). The set up is

                    GW:
                     |
              DLINK DGS 1100-08
              |               |
DLINK DGS 1100-05     Proprietary Access Point
 |              | 
Archer C7      DLink
(Openwrt)       |
               Archer C7
               (Openwrt)
               (The one with the problems)

All devices are within the 192.168.2.x subdomain

4

Is there a reason for having the switches?

5

The switches shouldn't be a problem, unless somehow misconfigured or faulty.

With both APs bridged to the network segment, it should work transparently.

I'd look at the ARP tables on the various devices (as best as their firmware permits) under "good" and "bad" conditions.

I'd also try swapping ports on the 1100-05 just to eliminate that possibility,

6

Or could you swap the two C7 routers and see what happens (or just remove the switch labelled "DLink"? I suspect it might be the one causing the trouble.

I wasn't suggesting the switch should be a problem. Was just noting that the network appears cumbersome.

7

I swapped the routers a lot of times, and the problem reoccurs each time. I'll try to remove the switch, perhaps that helps

8

Did you disable the DHCP server in the LAN interface for the C7s?

1 Like
9

So when you swap them, does the problem move with the same router or stay in the same location?

10

The problem stays in the same location. And yes I disabled dhcp on the LAN interface. I personally think this is a LAN routing problem where for some reason my atcher C7 acts as a gateway to the ISP gateway. I checked the ARP table and I didn't notice strange routes, but perhaps I overlooked some details.

11

Then it's worth trying swapping the ports as @jeff suggested, or remove the "DLink" switch and see if the prowled is correlated with the any of that.

12

This would be my first step, too.

13

Could you post from both normal and problematic C7 the following?
cat /etc/config/network; cat /etc/config/firewall; cat /etc/config/wireless ; cat /etc/config/dhcp ; ip -4 addr ; ip -4 ro ; ip -4 ru

14

I'll look into it.

This morning I did a hard (physical) reset instead of a soft reset, and the problem did'nt appear. Strange...

15

Hereby the output of problematic C7

IP - 4 addr

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1000
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
7: br-lan: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP qlen 1000
    inet 192.168.2.102/24 brd 192.168.2.255 scope global br-lan
       valid_lft forever preferred_lft forever

ip -4 ro

default via 192.168.2.254 dev br-lan 
192.168.2.0/24 dev br-lan scope link  src 192.168.2.102

ip -4 ru

0:	from all lookup local 
32766:	from all lookup main 
32767:	from all lookup default

And here the ones of the normal C7

ip -4 addr

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1000
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
7: br-lan: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP qlen 1000
    inet 192.168.2.104/24 brd 192.168.2.255 scope global br-lan
       valid_lft forever preferred_lft forever

ip -4 ro

default via 192.168.2.254 dev br-lan 
192.168.2.0/24 dev br-lan scope link  src 192.168.2.104

ip -4 ru

0:	from all lookup local 
32766:	from all lookup main 
32767:	from all lookup default