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Need for Speed
Winterville, NC

Network topology

I have always wondered about the network setup at SL.

For example, the first hop is about 7ms or so.

Just how far away might that be?

I guess the ping reply isn't the best indication of distance, but I still wonder, where is that equipment that is replying...
What the heck is a GatorKram? »www.gatorkram.com


Haughton, LA
wouldn't that be part of the cmts?


It would go your Modem (CPE) to CMTS to Router to Edge Router to Internet (in general)

Obviously there's always more switching and routing to be done depending on the best way to your destination. Some stuff might be local so it might never reach the edge routers. Some stuff goes thru CDNs instead as well.


Nitro, WV
reply to gatorkram
First hop might be in your neighborhood, or around that area. It is the CMTS, or headend. It's pretty similar in function to a Central Office (CO) for telephone or DSL, and those are usually local if not in a rural area.

The problem with using ping to measure distance is as follows. the circumference of the earth is about 25,000 miles. Light, and electromagnetic propagation travels at approximately 187,000 miles per second. Hence, the signal itself could traverse the complete circumference of the earth in 25000 miles/187000 miles per second = .133 s or 133 ms. At no point should a signal travel over half that circumference, so to get anywhere on the earth the signal propagation delay is approximately a maximum of 66.5ms.

A 1000 mile trip is about .5 ms

My point is, normally ping times because of distance are minimal. The delay you see are due to routing and switching, stuff that can't be performed at near lightspeed.

SDL L3Tech

Tyler, TX
reply to gatorkram
The first hop when connecting through a cable modem will always be the CMTS. The distance depends on where your house is located vs. where the Headend is.

Also, a cable connection has higher latency than fiber. From my experience, on a cable connection, the first hop is usually between 5-10 ms. The same distance on fiber would likely be 1ms or less.



1 edit
Yep, incredibly low (1ms - 2ms) to almost nonexistent (1ms) latency on our fiber networks for the first few hops. I'm guessing I'll have residential fiber available in my area around 20 years or so...


Nitro, WV
reply to gatorkram
The latency has to do with the shared nature, I'd venture to guess.

I remember a few years back, I pinged from my cisco router to the cable network, and got all kinds of replies from devices on the node, shocking to say the least, and speaks to the shared nature of cable.


reply to Chubbzie
That was supposed to be less than 1ms latency in my previous post.