# 722K broadband connect problem - arp issue



## wje (Mar 8, 2006)

My 622 recently died and was replaced with a 722k (about which I am not happy). I just noticed the 722 isn't getting a broadband connection now, never had a problem with the 622. The 722 gets the proper DHCP config set, but fails the broadband connect test. So, after much messing around (different routers, etc), I put a packet-sniffer on the network to see what was going on. The 722 sends a broadcast arp request to find my gateway, and never gets a response. Normally, I'd say this was a problem with the gateway, but no other device on my network has a problem, and neither did my 622. I'm out of ideas. Below is a packet trace. You can see that xx.12 does a broadcast and gets a response. xx.16 (the 722) does a broadcast and gets nothing. BOTH of these are on the same router (and I've tried 3 different routers, btw). 12 always works, 16 never works. I've included the expanded packet for 16's request, looks fine. Anyone have any ideas? (and no, I don't use ATT, and yes, I've put it behind other routers)

Time Source Destination Protocol Length Info
2 0.039335000 Azurewav_02:dd:88 Broadcast ARP 42 Who has 192.168.100.1? Tell 192.168.100.12
3 0.041220000 Netgear_46:5c:25 Azurewav_02:dd:88 ARP 60 192.168.100.1 is at 00:24:b2:46:5c:25
6 3.610808000 Echostar_ce:2b:32 Broadcast ARP 60 Who has 192.168.100.1? Tell 192.168.100.16

Frame 6: 60 bytes on wire (480 bits), 60 bytes captured (480 bits)
Ethernet II, Src: Echostar_ce:2b:32 (00:08:89:ce:2b:32), Dst: Broadcast (ff:ff:ff:ff:ff:ff)
Address Resolution Protocol (request)
Hardware type: Ethernet (1)
Protocol type: IP (0x0800)
Hardware size: 6
Protocol size: 4
Opcode: request (1)
[Is gratuitous: False]
Sender MAC address: Echostar_ce:2b:32 (00:08:89:ce:2b:32)
Sender IP address: 192.168.100.16 (192.168.100.16)
Target MAC address: Broadcast (ff:ff:ff:ff:ff:ff)
Target IP address: 192.168.100.1 (192.168.100.1)


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## wje (Mar 8, 2006)

Amazing how seeing something in a different format suddenly shows something you haven't noticed - note the request packet size. The one that works is 42 bytes, the 722 sends a 60 byte packet. Looking at arp requests on my network for a while, _every other device_ sends a 42 byte packet, and they all work. Looks like the 722 sticks a trailer on the packet, and no one will answer it. OTOH, from what I can find out about arp packet sizes, 60 is a possible size. So, I'm still not any closer to a solution.
My conclusion - for whatever reason, arp is broken on the 722, which, combined with all its other problems, makes it a candidate for the 'most useless dvr' award. I want my 622 back.


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## bnborg (Jun 3, 2005)

wje said:


> Amazing how seeing something in a different format suddenly shows something you haven't noticed - note the request packet size. The one that works is 42 bytes, the 722 sends a 60 byte packet. Looking at arp requests on my network for a while, _every other device_ sends a 42 byte packet, and they all work. Looks like the 722 sticks a trailer on the packet, and no one will answer it. OTOH, from what I can find out about arp packet sizes, 60 is a possible size. So, I'm still not any closer to a solution.
> My conclusion - for whatever reason, arp is broken on the 722, which, combined with all its other problems, makes it a candidate for the 'most useless dvr' award. I want my 622 back.


Very interesting. The problem has been discussed before, in threads such as *722k always appears offline?* and *Sling box drops connection* but this is the first real insight as to a cause. I am going to look at the advanced settings on my router and see if there is any way to enable trailers or somthing related.


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## wje (Mar 8, 2006)

After leaving the packet sniffer running for a while, I did see some other arp requests from other devices with a 60 byte payload. Interestingly, those got a response. So, the packet size itself isn't the determining factor.


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## bnborg (Jun 3, 2005)

I have configured my router's dhcp server with an assigned ip of 192.168.2.40 for my ViP722k.

The arp request I am seeing is "ARP:Request, 192.168.2.40" asks for 255.255.255.127, but it is being broadcast to everyone, TargetMacAddress: FF-FF-FF-FF-FF-FF. Is this maybe looking for a subnet? If so, I don't know why. The DVR has a normal subnet mask, 255.255.255.0, as does the router. There is no device on my network with a matching IP (*.*.*.127, no subnet).

With that request it's not going to get an answer. Maybe if I assign 192.168.2.127 to the router something?


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