Losing route to host on local network

[mazoo]

I am experiencing a strange problem with my network. I have a AC68U with several machines connecting over wireless, including a raspberry pi. The problem I am having is I intermittently can't connect to or ping the raspberry pi. To start with I thought it was a problem with the device, but I then found that if I connect into my router and then connect from the router to the raspberry pi the connection is fine. I have seen this connection issue from more than on machine.

Any ideas what might be going on here?

Thanks

Mazoo

 

[stevech]

I am experiencing a strange problem with my network. I have a AC68U with several machines connecting over wireless, including a raspberry pi. The problem I am having is I intermittently can't connect to or ping the raspberry pi. To start with I thought it was a problem with the device, but I then found that if I connect into my router and then connect from the router to the raspberry pi the connection is fine. I have seen this connection issue from more than on machine.

Any ideas what might be going on here?

Thanks

Mazoo

I have an RPi with a Buffalo USB WiFi dongle. It is in the same room as the WiFi router. It so far (weeks) has been trouble free. RPi runs 24/7 but does connect OK when I reboot it.

Make sure the RPi's list of WiFi networks to use omits all but yours. The RPi's WiFi might try to change and connect to a nearby unencrypted SSID in the list.

Try giving the RPi a static LAN address outside your router's DHCP range. This eliminates the possibility of a DHCP lease renewal protocol problem.

In my router, I have a DHCP reservation so the RPi uses DHCP but always gets the same LAN IP assigned. That lets me use VNC from my desktop with the RPi, which works surprisingly well.

 

[jlake]

I am experiencing a strange problem with my network. I have a AC68U with several machines connecting over wireless, including a raspberry pi. The problem I am having is I intermittently can't connect to or ping the raspberry pi. To start with I thought it was a problem with the device, but I then found that if I connect into my router and then connect from the router to the raspberry pi the connection is fine. I have seen this connection issue from more than on machine.

Any ideas what might be going on here?

Thanks

Mazoo

Check your log to see if your router is randomly rebooting. There's a bug.

http://forums.smallnetbuilder.com/showthread.php?t=15628

 

[mazoo]

Make sure the RPi's list of WiFi networks to use omits all but yours. The RPi's WiFi might try to change and connect to a nearby unencrypted SSID in the list.

I am explicity setting the SSID in /etc/network/interfaces plus there are no other network in the area, I live out in the woods

Try giving the RPi a static LAN address outside your router's DHCP range. This eliminates the possibility of a DHCP lease renewal protocol problem.

I will give this a try

In my router, I have a DHCP reservation so the RPi uses DHCP but always gets the same LAN IP assigned. That lets me use VNC from my desktop with the RPi, which works surprisingly well.

This is how I currently it setup

 

[mazoo]

Check your log to see if your router is randomly rebooting. There's a bug.

http://forums.smallnetbuilder.com/showthread.php?t=15628

I don't think its a reboot issue, uptime shows over 7 days and the problem has occur in that time.

 

[mazoo]

I am afraid assigning a static ip didn't help

 

[joshka]

I had a similar issue the other day, which has me scratching my head about how networking works. From my macbook (connected over wifi) to foci (connected via ethernet):

~ ping foci
ping: cannot resolve foci: Unknown host

~ nslookup foci
Server: 192.168.1.1
Address: 192.168.1.1#53

Name: foci
Address: 192.168.1.229

~ traceroute foci
traceroute: unknown host foci

~ ping foci
ping: cannot resolve foci: Unknown host

~ traceroute foci
traceroute: unknown host foci

~ nslookup foci
Server: 192.168.1.1
Address: 192.168.1.1#53

Name: foci
Address: 192.168.1.229

~ ssh 192.168.1.229
Last login: Thu May 1 01:28:24 2014 from joshka-macbookpro
joshka@foci ~ exit
Shared connection to 192.168.1.229 closed.

~ nslookup foci
Server: 192.168.1.1
Address: 192.168.1.1#53

Name: foci
Address: 192.168.1.229

~ ping foci
ping: cannot resolve foci: Unknown host

~ ping 192.168.1.229
PING 192.168.1.229 (192.168.1.229): 56 data bytes
64 bytes from 192.168.1.229: icmp_seq=0 ttl=64 time=3.294 ms
64 bytes from 192.168.1.229: icmp_seq=1 ttl=64 time=3.313 ms

~ arp foci
arp: foci: Unknown host

~ arp 192.168.1.229
foci (192.168.1.229) at 28:92:4a:2b:b:13 on en0 ifscope [ethernet]

It seems some parts of the system know where the host is, but some don't. It has since corrected itself, so this is just here in case it prompts insight from someone that knows a bit more about Layer 2 and 3 than me (and in case it happens again).

 

[ColinTaylor]

It seems some parts of the system know where the host is, but some don't. It has since corrected itself, so this is just here in case it prompts insight from someone that knows a bit more about Layer 2 and 3 than me (and in case it happens again).

It looks like you're running OSX which may be different, but if you ran those commands on a windows box I wouldn't be surprised. In Windows if you don't specify a domain for the host you're pinging it will only try to resolve it as a NETBIOS name. If you're not part of a domain the following is the correct syntax and should work:

ping foci.

 

[joshka]

It looks like you're running OSX which may be different, but if you ran those commands on a windows box I wouldn't be surprised. In Windows if you don't specify a domain for the host you're pinging it will only try to resolve it as a NETBIOS name. If you're not part of a domain the following is the correct syntax and should work:

ping foci.

Yes OSX.

I'm a little confused about your netbios explanation as I've had this working recently in the same network without any need to specify the terminating period. But perhaps there's some related netbios secondary fall back logic that I didn't see before. I've since added a domain suffix to the DHCP settings, which is possibly why it's all now working fine.

 

[ColinTaylor]

Yes OSX.

I'm a little confused about your netbios explanation as I've had this working recently in the same network without any need to specify the terminating period. But perhaps there's some related netbios secondary fall back logic that I didn't see before. I've since added a domain suffix to the DHCP settings, which is possibly why it's all now working fine.

Hi, Glad you got it working.

As you're running OSX the NETBIOS thing if probably irrelevant. I don't know anything about OSX but a quick google finds various discussions about short name resolution. They discuss the function of the trailing dot and also point to settings in the "Search Domains".

Here's two such discussions: http://serverfault.com/questions/47...ified-hostnames-work-with-mountain-lion-tunne and http://superuser.com/questions/1843...-for-in-the-tcp-ip-dns-settings-control-panel

But, as you've got it working now it might be best to leave it alone.

UPDATE: I've just seen that other post by hevaKmaI that you linked back to here... I'd forgotten about that Apple-voodoo stuff, mDNS, avahi, Bonjour. I don't understand it but it sounds a bit like NETBIOS's local name resolution.

 

[hevaKmaI]

I'm still experiencing issues with my computers often losing local name resolution after a day or so. Only rebooting the router will fix it. Did you ever find a fix?

 

[bradr]

I'm still experiencing issues with my computers often losing local name resolution after a day or so. Only rebooting the router will fix it. Did you ever find a fix?

We have this as well. Seems related to the fact that ASUS router is reporting itself as a Wins Server, even thouh in the DHCP field we have Wins turned off.

I think i am going to have set up a quick linux box, move dhcp wins, etc over to it to work around the issues from the ASUS router.