How internet works
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How internet works
Ok, sounds like a silly newby question, isn't it? Well, it's not. Ok, maybe it is.
Just know I have a lot of trouble connecting to some websites. Not all, but many. maybe 1/3 or 1/2 of sites I try to access don't respond (connection has timed out). I tested my own connection and all is fine (upload 4412 kbps, download 570 kbps, 848.0 Conn/min). Devnetwork flies as always. Sitepoint is not accessible.
So how can this be? It isn't the connecntion from my house to the cable. Is internet traffic clustered, and therefore if one cluster is having problems a whole set of websites is not accessible? Could it be a problem in my region?
Just know I have a lot of trouble connecting to some websites. Not all, but many. maybe 1/3 or 1/2 of sites I try to access don't respond (connection has timed out). I tested my own connection and all is fine (upload 4412 kbps, download 570 kbps, 848.0 Conn/min). Devnetwork flies as always. Sitepoint is not accessible.
So how can this be? It isn't the connecntion from my house to the cable. Is internet traffic clustered, and therefore if one cluster is having problems a whole set of websites is not accessible? Could it be a problem in my region?
- Chris Corbyn
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- Joined: Wed Mar 24, 2004 7:57 am
- Location: Melbourne, Australia
Re: How internet works
It's quite literally like a web. To get to any one server you need to go via many others. Try using the program tracert in windows or traceroute in linux. That will show you how many servers you go through to get here for example.matthijs wrote:Ok, sounds like a silly newby question, isn't it? Well, it's not. Ok, maybe it is.
Just know I have a lot of trouble connecting to some websites. Not all, but many. maybe 1/3 or 1/2 of sites I try to access don't respond (connection has timed out). I tested my own connection and all is fine (upload 4412 kbps, download 570 kbps, 848.0 Conn/min). Devnetwork flies as always. Sitepoint is not accessible.
So how can this be? It isn't the connecntion from my house to the cable. Is internet traffic clustered, and therefore if one cluster is having problems a whole set of websites is not accessible? Could it be a problem in my region?
You send a request to DNS server first and foremost, that could possibly have issues itself and not know the IP of the server. If that responds with an IP, you then start looking for a route to the server, at which point you'll sort of hop from zone-to-zone until you end up there. The further away the server is, logically the more hops you'll make. Think of it like this: you don't have a direct cable between sitepoint and devnetworks.
- daedalus__
- DevNet Resident
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- Joined: Thu Feb 09, 2006 4:52 pm
if you do a search on google for something simple like 'how does the internet work' or look up some stuff on HTTP you can find some pretty simple or pretty complicated explantions. this one time, when i was younger and nubber i was looking for an answer to the question and i came across a 40-some page paper about http and how the internet works :O
Thanks for the input. I do basicly know how the internet works (read Shiflett's book on http), but I find it strange that today a lot of sites do not load, while others do. And it's not just a random occasional site which is offline. There are many.
So maybe I should refrase my question: is it possible that a whole cluster of websites is inaccessible because of some failure somewhere in a network centre?
@SomeOne: please explain what you mean. I am on a windows system, yes. But what is MTU?
So maybe I should refrase my question: is it possible that a whole cluster of websites is inaccessible because of some failure somewhere in a network centre?
@SomeOne: please explain what you mean. I am on a windows system, yes. But what is MTU?
- Chris Corbyn
- Breakbeat Nuttzer
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- Joined: Wed Mar 24, 2004 7:57 am
- Location: Melbourne, Australia
Yes. How can I explain this... Hmmm. OK, you have different routes to different locations.matthijs wrote:So maybe I should refrase my question: is it possible that a whole cluster of websites is inaccessible because of some failure somewhere in a network centre?
For example, imagine you've set up intranet in your house, and each computer has access to the internet.
Now, to get the Jim's computer downstairs with IP address 192.168.1.4 from your own PC, where do you go?
2 hops: PC -> Router, Router -> Jim
Now, you ask for Kayleigh's PC with IP 192.168.1.6. Same thing, 2 hops. Now if your router was down you'd never make that first hop so you wouldn't reach kayleigh or jim, but kayleigh and jim's PCs may be functioning completely fine. It's the same situation with the internet but on a larger scale.
Let's say you ask for Google. How many hops? Let's see?
Code: Select all
cac @walnut ~$ traceroute www.google.com
traceroute: Warning: www.google.com has multiple addresses; using 64.233.183.104
traceroute to www.l.google.com (64.233.183.104), 30 hops max, 46 byte packets
1 nodns (192.168.2.2) 0.945 ms 0.903 ms 1.071 ms
2 dhcp-6-4 (192.168.6.4) 0.093 ms 0.115 ms 0.127 ms
3 border-router (213.205.138.153) 1.498 ms 1.411 ms 1.241 ms
4 s6-1-5-0.ar01.sbc.bb.pipex.net (212.241.252.46) 1.744 ms 1.790 ms 1.729 ms
5 g0-2-790.cr01.sbv.bb.pipex.net.132.72.62.in-addr.arpa (62.72.132.186) 1.998 ms 2.076 ms 2.104 ms
6 g0-2.cr04.tn5.bb.pipex.net (62.72.156.106) 7.632 ms 7.200 ms 7.230 ms
7 g3-25-6.cr05.tn5.bb.pipex.net (62.72.140.133) 7.500 ms 7.541 ms 7.852 ms
8 195.66.224.125 (195.66.224.125) 7.880 ms 7.841 ms 7.600 ms
9 216.239.43.91 (216.239.43.91) 16.745 ms 16.930 ms 25.718 ms
MPLS Label=176270 CoS=0 TTL=127 S=0
10 72.14.232.141 (72.14.232.141) 18.714 ms 19.129 ms 18.597 ms
11 72.14.233.77 (72.14.233.77) 19.225 ms 18.514 ms 18.460 ms
12 216.239.43.34 (216.239.43.34) 21.733 ms 27.263 ms 18.979 ms
13 64.233.183.104 (64.233.183.104) 19.485 ms 25.139 ms 18.838 msThanks for the explanation chris. Is quite logical.
And indeed it seems there has been a problem with a server/network point somewhere. Just 5 mins ago I tried reloading the sites I couldn't access (Sitepoint, news sites, etc) and suddenly they all loaded fine again.
I would think that if a certain hop is blocking the traffic, an alternative route should be available, isn't it? Because while 50% of the sites were accessible, the other 50% wasn't? But that means it has been my own ISP? A problem in a local hop?
Interesting stuff
And indeed it seems there has been a problem with a server/network point somewhere. Just 5 mins ago I tried reloading the sites I couldn't access (Sitepoint, news sites, etc) and suddenly they all loaded fine again.
I would think that if a certain hop is blocking the traffic, an alternative route should be available, isn't it? Because while 50% of the sites were accessible, the other 50% wasn't? But that means it has been my own ISP? A problem in a local hop?
Interesting stuff
- Chris Corbyn
- Breakbeat Nuttzer
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- Joined: Wed Mar 24, 2004 7:57 am
- Location: Melbourne, Australia
Yep, this is usually the case. You set up a cluster of servers and can use any one of them. The problem is, if the gateway to this cluster goes down (one server!) then it will fail. This gateway could be something referred to as an LVS which is basically a load balancer directing traffic to the individual servers in the cluster.matthijs wrote:I would think that if a certain hop is blocking the traffic, an alternative route should be available, isn't it? Because while 50% of the sites were accessible, the other 50% wasn't? But that means it has been my own ISP? A problem in a local hop?
Interesting stuff
Another way clustering can be handled is that, at the name resolution end of the scale the name can resolve to multiple IP addresses. This is what's called "round-robin" and is what Google appear to do when you ask for google.com, and end up on one of their many masses of servers.
Code: Select all
traceroute: Warning: www.google.com has multiple addresses; using 64.233.183.104
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SpiderMonkey
- Forum Commoner
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Yeah, I had to think about it as well when posting my question 
For anyone who doesn't know what we are talking about: http://www.youtube.com/watch?v=DClkE64nFDY
For anyone who doesn't know what we are talking about: http://www.youtube.com/watch?v=DClkE64nFDY