US Cable Support > Comcast HSI > [Speed] Valid Comcast Speed Measurement?

reply to dr2500

Re: [Speed] Valid Comcast Speed Measurement?

Have you bypassed the router?

That router tops out at 7 megs with the firewall turned off. Looks like 2002 router.
»smallnetbuilder.com/component/op···art,119/
Look all the way down almost at the bottom

I downloaded the file and it was shown at 280 kilobytes per second under Windows XP. This is roughly 2.2megabits per second. I have connected the PC (2GHZ)to the modem with no obvious change in performance. However, as noted the Internet is far from a stable environment and once you are beyond one hop more and more doubt creeps in. I need to use the Comcast file direct to the modem next.

I am now confused by the tier descriptions. I had seen this in other messages and was going to ask about it anyhow. First, I believe I am on a 6 megabit per second tier download. If I look at the example on the 8 megabit per second it says that "The 8meg tier is essentially 1MB/sec". This is where I become confused. What is the relationship between 8 megabits/sec and the 1 megabits/sec? Which value is seen in the speed tests?

Thanks & regards,
Dick

Their relationship is pretty easy to understand. 8Mb/sec is the same as 1MB/sec. Notice the difference in the B, B = Bytes, b = Bits. There are 8 Bits to a Byte. Thus, 8 Megabits/sec equals 1 MegaByte/sec.

If you wanted to calculate that, you need to transition megabits into bits for easier computation. In this case 8Mb is 8192 bytes (8 * 1024). 6Mb is 6144 (6 * 1024). There are 1024 bits in a megabit. Now that you have the number in bits you can convert that to bytes by dividing by 8 (remember the 8 bits in a byte). Thus, 8192 bits is equal to 1024 bytes and 6144 bits is equal to 768 bytes.

All you really need to be concerned with is that 8 Megabits/sec means 1 MegaByte/sec and 6 Megabits/sec means 768 KiloBytes/sec (or 0.786 MegaBytes/sec). Given you got 280KB/sec off of the Comcast install file I would say your issue definitely lies with Comcast. Comcast's network consists of 10 Gigabit/sec links between virtually everything with the exception of the link between the core routers and the CMTS which is 1 Gigabit/sec. It would take a LOT of traffic to saturate that kind of a link. Most systems are now interconnected via the same 10Gb links so you should never hit the public internet even when talking to a Comcast server in another state. Now, I can't say what the cause of your issue is given the information at hand.

Joel

reply to boleyd
If you don't know how to check your signal level in your modem check this FAQ out.
»Cable Modems and Wiring Issues

Please post.

reply to JoelC707
So the iussue is with the "B" word (byte or bit). When I managed a larger corporation's comms net the rule was to always use bits per second when referring to communications transfer rates. Bytes were used to denote storage and memory factors. I guess that there has been some drift from that convention. So the elderly are confused.

I have not seen any PowerBoost propaganda here so I believe that we are pure vanilla in that regard. Since I do get 4.5mbits/s at times I can suspect some net router, or my modem, or my drop line is faulty. From my past experiences a suspect would be a router config. I will check the modem signal level. My scope only goes to 20mhz so it is not the instrument of choice. The software snmp process is involved so that will take time.
EDIT- Comcast appears to have blocked the SNMP for my Surfboard 3100 modem. Looks like I will have to endure the resets and param checks of "customer service". Then await truck dispatch. My HDTV does occasionally have some pixels but not bad enough to make the dreaded call. Time to fix everything.

Regards,
Dick

From Comcast FAQ
SB3100D Can't find your manual? View it on Comcast.net! (requires Adobe Reader)

This modem cannot be upgraded to comply with the DOCSIS 1.1 specification. If you currently use this model it is not necessary to remove it from the network. However, this device should not be returned to service if sent back to the warehouse, nor should it be purchased for use with the Comcast High-Speed Internet Service.

reply to boleyd
If you're still using the 3100 then I think you're due for an upgrade. That model is ancient...

Thanks for the FYI on the 3100....