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Problem with ARP?

Support Roadshow

Moderators: AndreasM, olsen

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Kokos
Grade reingestolpert
Grade reingestolpert
Posts: 2
Joined: 27.06.2015 - 10:23
Location: Chotomów

Problem with ARP?

Post by Kokos »

Hi guys,

I bought Roadshow for my Amiga 1200 + WiFi card (Prism2).

For some reason DHCP is not working for my A1200 and I needed to set up everything manually.

Generally A1200 after fresh reboot can access network items easily except default gateway itself. This means when I ping default gateway (192.168.1.1) I receive 100% loss. Similarly when I ping A1200 from any PC in the network (let's say 192.168.1.40) I also receive 100% loss with information - 'Destination host unreachable'.

But everything changes for a while when I ping from A1200 any network item for example 192.168.1.40 - then I receive response and after that I can ping gateway as well and also PC (192.168.1.40) can reach A1200 without any problem.

I noticed that it depends on ARP table.. PC don't have A1200 in ARP table until it PC will receive a network packet from A1200.. But then after some time it disappears from ARP.

I'm not sure what's the right way to resolve this.. Shall Amiga keep sending some pocket broadcasts to every item in the network to keep connection alive?

Thank you for any suggestions. Please let me know whether you need to more for investigation.

Kind regards,
Konrad

olsen
CygnusEd Developer
Posts: 117
Joined: 06.06.2006 - 15:27

Re: Problem with ARP?

Post by olsen »

Kokos wrote:Hi guys,

I bought Roadshow for my Amiga 1200 + WiFi card (Prism2).

For some reason DHCP is not working for my A1200 and I needed to set up everything manually.

Generally A1200 after fresh reboot can access network items easily except default gateway itself. This means when I ping default gateway (192.168.1.1) I receive 100% loss. Similarly when I ping A1200 from any PC in the network (let's say 192.168.1.40) I also receive 100% loss with information - 'Destination host unreachable'.

But everything changes for a while when I ping from A1200 any network item for example 192.168.1.40 - then I receive response and after that I can ping gateway as well and also PC (192.168.1.40) can reach A1200 without any problem.

I noticed that it depends on ARP table.. PC don't have A1200 in ARP table until it PC will receive a network packet from A1200.. But then after some time it disappears from ARP.

I'm not sure what's the right way to resolve this.. Shall Amiga keep sending some pocket broadcasts to every item in the network to keep connection alive?

Thank you for any suggestions. Please let me know whether you need to more for investigation.

Kind regards,
Konrad
How does your network interface configuration file look like? For reference, here is a working example for the A2065 Ethernet card:

Code: Select all

device=a2065.device
unit=0
configure=dhcp
debug=yes
After you have brought the network interface online, how does the output of the "ShowNetStatus" command like? For reference, entering "shownetstatus a2065" might produce the following:
Interface "a2065"
Device name = a2065.device
Device unit number = 0
Hardware address = 00:80:10:47:17:11
Maximum transmission unit = 1500 Bytes
Transmission speed = 10000000 Bits/Second
Hardware type = Ethernet
Packets sent = 5
Packets received = 46
Packets dropped = 0 (in = 0, out = 0)
Buffer overruns = 0
Unknown packets = 0
Address = 192.168.1.79
Network mask = 255.255.255.0
Number of read I/O requests = 36 (maximum of 1 used at a time, 36 are still pending)
Number of write I/O requests = 32 (maximum of 2 used at a time, 0 are still pending)
Number of bytes received = 704
Number of bytes sent = 740
Transfer statistics (in/out) = DMA:0/0 Byte:3/5 Word:-/0
Address binding = Dynamic
Address lease expires = 27.06.2015 15:36:55
Link status = Up
This is an example of a working configuration which succeeds in contacting the local network's DHCP server, obtains a dynamically assigned IPv4 address and can be used to ping the server.

You are correct to state that ARP is essential for Roadshow, and in fact any TCP/IP stack to work if network interfaces using Ethernet (IEEE 802.3) or WLAN (IEEE 802.11) are involved. Because ARP is essential, I am cautious to view it as the root of the problem.

Kokos
Grade reingestolpert
Grade reingestolpert
Posts: 2
Joined: 27.06.2015 - 10:23
Location: Chotomów

Post by Kokos »

Hi olsen,

Thanks for your quick reply.

Here's my configuration for DHCP (it's pretty default):

Prism2 NetInterface:

Code: Select all

device=prism2.device
configure=dhcp
requiresinitdelay=no
ShowNetStatus prism2:

Code: Select all

Interface "prism2"
Device name                  = prism2.device
Device unit number           = 0
Hardware address             = 00:02:2D:BE:BF:0E
Maximum transmission unit    = 1500 Bytes
Transmission speed           = 11000000 Bits/Second
Hardware type                = Ethernet
Packets sent                 = 11
Packets received             = 3
Packets dropped              = 8 (in = 0, out = 0)
Buffer overruns              = 0
Unknown packets              = 0
Address                      = (Not configured)
Network mask                 = (Not configured)
Number of read I/O requests  = 36 (maximum of 0 used at a time, 36 are still pending)
Number of write I/O requests = 32 (maximum of 1 used at a time, 0 are still pending)
Number of bytes received     = 0
Number of bytes sent         = 1 312
Transfer statistics (in/out) = DMA:0/0 Byte:0/4 Word:-/0
Link status                  = Up
And these are for my static settings:
Prism2 NetInterface:

Code: Select all

device=prism2.device
address=192.168.1.126
netmask=255.255.255.0
requiresinitdelay=no
ShowNetStatus prism2:

Code: Select all

Interface "prism2"
Device name                  = prism2.device
Device unit number           = 0
Hardware address             = 00:02:2D:BE:BF:0E
Maximum transmission unit    = 1500 Bytes
Transmission speed           = 11000000 Bits/Second
Hardware type                = Ethernet
Packets sent                 = 7
Packets received             = 3
Packets dropped              = 3 (in = 0, out = 0)
Buffer overruns              = 0
Unknown packets              = 0
Address                      = 192.168.1.126
Network mask                 = 255.255.255.0
Number of read I/O requests  = 36 (maximum of 0 used at a time, 36 are still pending)
Number of write I/O requests = 32 (maximum of 2 used at a time, 0 are still pending)
Number of bytes received     = 0
Number of bytes sent         = 56
Transfer statistics (in/out) = DMA:0/2 Byte:0/0 Word:-/0
Address binding              = Static
Link status                  = Up
Static configuration works for me, except that ARP thing I mentioned in first post. I don't mind using static configuration, but in that case I need to resolve issue with that ARP broadcasting..

Thanks for any suggestions!

olsen
CygnusEd Developer
Posts: 117
Joined: 06.06.2006 - 15:27

Post by olsen »

Kokos wrote:Hi olsen,

Thanks for your quick reply.

Here's my configuration for DHCP (it's pretty default):

...
Thank you, this looks fine to me. The hardware address appears to be sound. As for the missing ARP information, not a lot could to go wrong.

It could be that the ARP information is not cached long enough. ARP associates IP addresses (such as the 192.168.1.126 which you picked) with the hardware address (00:02:2D:BE:BF:0E). This association is retained for a short interval, which typically is around 60 seconds. It's unlikely, but the system which has difficulties finding your device could be forgetting it too soon, e.g. if the local clock is running too quickly or is reset.

It could be that the static IP address which you picked is already in use. In this case other computers which are trying to reach your machine will end up sending the data to the other user of this IP address. It could happen.

It could be that the network you are using is suffering from reliability issues, such as due to signal interference. ARP request packets are usually sent 1-3 times, and the ARP response packet which Roadshow sends may get lost. Can you check your WiFi router to get a reading on how much packets were lost, dropped, etc?

That's as much as I can think of which could be the cause of the problem.

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