Cable Modem Dilema

[SomeFknGuy]

Have a question for you guys. For about the last 6 months or so, my cable modem has been wigging out badly. Its a Toshiba PCX-1100(yeah i know...they are supposed to suck...) and it has a habbit of resetting itself, just basically warm booting itself, once every 30-45 minutes.... At first i thought it was the modem, but i got to looking deeper into the problem, i bypassed my router and went straight to the ethernet port from pc->modem and cranked up my good buddy Ethereal. What i found was quite interesting. In the time span of roughly 5 minutes, i had over 25000 ARP request packets nail my modem... Now i dont know if this is enough to freak out my modem and force it to reset, but even with everything but the coax disconnected from the modem, the traffic light on the modem is completely solid as though im downloading at full speed. I have also noticed as of late(in the last .5-1 years) a major speed reduction, not necisarilly in throughput, as i can still get near 4.5-5 megs, but latency. most games i play will not ping under 85ms in the game, where as when i first got the modem, latencys were in the 35-50 ms range. I dont know if the modem is just having so much trouble parsing the traffic that its killing the latency or what. I have been tossing around the idea of replacing the Toshiba with a SURFboard 5100 docsis2 modem, which with any luck from what ive read, is a much more stable and managable system. My biggest question for you folks, what do you recommend or think on this? Ive tried contacting my isp(cox.net) tech support, they couldnt tell me anything other than "reboot the modem or try limiting the amount of ARP traffic on your end" and i just hung up after that... So would you guys try replacing the modem? Thats my next step, and once i do that, what should i do to try to battle the ARP traffic i seem to be getting flooded with?

Any help much appreciated
Thanks again
Jhonathan

 

[IceWindus]

Easiest step that won't strain your brain and will give you a clear cut yes or no on the modem being the problem is simpy replace the modem with a Motorola 5100 Surfboard. Almost every single person who uses them swears by them.

Keep in mind also, cable is shared bandwith by nature. That being said, when you first got the service, there was probably few people on your frequency "loop" sharing the bandwith. As a result, you got almost full bandwith and low latency. As time when on, more and more people are attaching to that same frequence that you all share. So if Johnny Blow is deciding to download a Gig of pron on his machine, EVERYONEs bandwith and latency will suffer slightly. Thats the big reason why cable companies dont' allow people to host servers on cable connections.

If you add several people or more doing that, depending on how large the loop is, network, server setup, ect..ect... their are a variety of factors that could now be resulting in your cable problems. Typically most cable companies will change the loop size and frequency to combat this to allow peeps the most bandwith available for everyone, but thats all up to them and being cable, your not on a dedicated connection like your are with DSL.

First step is simply replace the modem with a surfboard. If you still continue to have problems, it may be time to start speaking with the cable reps and request a bandwith check in you area and explain what has happened since you first signed up.

Also remember when you replace the modem, you will need to call in and tell them your new MAC address from the modem so they can update their routers to send your packets to the correct modem.

 

[Uncle Toxie]

I have actually seen this before. I used to work in Tier 2 support for Charter Cable and almost every time I saw this it ended up being someone in your neighborhood either stealing cable or they have jacked with the tap trying to fix thier own cable. This is a real pain in the ass to track down and if Cox is anything like Charter you will either have to keep calling back untill you speak to a tech with a clue or just raise holy hell when you do call.

 

[SomeFknGuy]

the flooded node thing is a definate possibility, especially with broadcast ARP packets flying around like nobodies business, im a tier 2 for a local ISP so im pretty good with networking itself, im just trying to get other ideas before i take my toshiba out back and shoot it... lol... but my neighborhood, the majority of it is old people and ghetto...so all in all i doubt its massive pr0n surfing, but hey you never know, hopefully, just hopefully, i can get this all straightened out, you know how hard it is to play halo online with a 100 ping!

 

[Uncle Toxie]

Try not to hurt the Tier 1 agents too much when you call in .

I remember the Toshibas being a major pain in the butt too, if you got it from Cox and they will replace it I would suggest the Motorola over it for sure. Good luck!

 

[SomeFknGuy]

i used to have an old toshiba docsis 1.1 modem back in the day that was provided by cox and was dying out(then i bought the newer toshiba), i got rid of it for a pcx 1100(i think, im at work right now, cant check lol) but im thinkin this new toshiba is dying out too, so we shall see, thanks for the info guys

 

[tiebird321]

the high volume of arp packets is pretty normal
remember the downstream on a cable is the same as a hub
every modem on the cable in a loop sees every single packet/arp request
also a good deal of cable companies give each local loop a block of ips weather or not they are all being used
this makes routing and network management simpler
i dont know if cox does this or not
so if there is someone out there port scaning (which there always is) there is going to be a huge amount of arp traffic

i dont know about one cable modem vs another

but i can very well see one modem just having issues with the hevy trafic
as for the ping times....
porbobly just more traffic in the exchange