point-to-point link for thousands of kilometers possibility

Status
This thread has been Locked and is not open to further replies. Please start a New Thread if you're having a similar issue. View our Welcome Guide to learn how to use this site.

zillah

Thread Starter
Joined
Jun 6, 2005
Messages
333
“Computer Networks” book by ANDREW S. TANENBAUM Ed4th Article 5.5.2 How Networks Can be Connected page 421 (Figure 5-44) he says:

“------Now let us consider the same situation but with two Ethernets connected by a pair of routers instead of a switch. The routers are connected by a point-to-point, possibly a leased line thousands of kilometers long.”.

Here he mentioned physical leased (dedicated) line.

Is practically (real life) this line available for thousand of kilometers ?
 
Joined
Oct 20, 2003
Messages
1,625
Yes. You buy a leased line from a provider (eg BT in the UK, and they are not cheap, 10Mbps starting at £5750 connection charge plus £9000pa rental, minimum 12 months contract); you've bought yourself a dedicated line. It's what they're in business for.

Basically you're renting a constant end-to-end uncontended connection with very high levels of availability, regardless of traffic. The circuits are maintained and guaranteed by the provider.
 

zillah

Thread Starter
Joined
Jun 6, 2005
Messages
333
The circuits are maintained and guaranteed by the provider.
Is it physical cable connect my home or office or Enterprice to the second end (different contury) or it is logical connection ?
 

JohnWill

Retired Moderator
Joined
Oct 19, 2002
Messages
106,425
Normally, you'd be buying a "logical" connection, since a long distance connection will be going through many facilities. I think that leased lines the way he describes have gone the way of the Dodo bird for the most part, just too expensive. In the 80's, I was building trading equipment for NYSE and some of the member firms. We had leased lines running all around the world, and the costs were staggering! Nowadays, most folks use a VPN and the Internet backbone for such chores, much cheaper.
 
Joined
Oct 20, 2003
Messages
1,625
I was thinking of a case, project I worked on, where a leased line to the radiation detectors (post-Chernobyl) on a remote Scottish island was running at £20K per year (plus installation cost, the cable was led by helicopter). Then the reindeer ate the b***** cable! :)
But leased lines were still being rolled out two years ago for British Gas (mainly as backup to sat links) pipeline monitoring stations. Agreed, the costs are staggering, but not quite gone the way of the Dodo yet, they are still a nice little earner for BT.
 

zillah

Thread Starter
Joined
Jun 6, 2005
Messages
333
Is it physical cable connect my home or office or Enterprice to the second end (different contury) or it is logical connection ?
The routers are connected by a point-to-point, possibly a leased line thousands of kilometers long
Because it is difficult to imagine that there is physical connection led (Thousand of km) between TNT in Sydney and Cisco in US through ocean.


I think that leased lines the way he describes have gone the way of the Dodo bird for the most part, just too expensive.
Does that mean these days we can expect this type of connection rare ? and If we expected only within the country ?


But leased lines were still being rolled out two years ago for British Gas
Within same country, or between neighbor countries.
 

zillah

Thread Starter
Joined
Jun 6, 2005
Messages
333
£20K per year
Was 20000 the cost per unit or rent ?

If the physical cable exist,,,that means we have very high security, because there is no expectation of evasdrop
 
Joined
Oct 20, 2003
Messages
1,625
zillah said:
Because it is difficult to imagine that there is physical connection led (Thousand of km) between TNT in Sydney and Cisco in US through ocean.
Why is this difficult to imagine? Cables have been led in the oceans for 100+ years now (eg Trans-Atlantic since 1850s, http://www.newscotland1398.net/victco/cabotcablem.html). In the days before satellites I should imagine similiar were led between Australia and the US! These were indeed literal physical point-to-point connections (albeit not for Ethernet!).

The £20Kpa was rental on a physical cable, point-to-point leased line; the only thing on the remote end was a (fairly) dumb, monitoring device stuck in the middle of a field (basically a geiger counter with some comms software).

zillah said:
Does that mean these days we can expect this type of connection rare ? and If we expected only within the country ?
.
No (in answer to second question). Back on the gas project: leased line backups were (are - the system is still live) used from the main 8m dish site in the UK and a site in Germany (in the event the dish talking to the bird fell off its mounting, etc!).
 

Squashman

Trusted Advisor
Joined
Apr 4, 2003
Messages
19,786
Well there is alot of Dark Fiber out there and Google has been buying it up.
 

zillah

Thread Starter
Joined
Jun 6, 2005
Messages
333
Thanks coulterp for this explaination

I want to ask few other questions to clarify the concepts

Because it is difficult to imagine that there is physical connection led (Thousand of km) between TNT in Sydney and Cisco in US through ocean.
I can imagine that there is cable between these two countries (and other countries), and this cable has got thousands of pairs of wire inside it. For this point-to-point line the carrier allocates pairs of wire and facility hardware to your line only (my case TNT and Cisco).





But I can not imagine one physical cable (one pair of wire inside it) to connect only (because there are no other pairs of wire availabe to other parties) two specific parties, in two different countries.
The reason I can not imagine that, according to the definition of point to point link that I found "TCP/IP Protocol Suite" book by Behrouz A. Forouzan 3 Edth,,,,Under Article Point-to-Point Link page 405 he says:

" A point-to-point link connects two routers without any other hosts or routers in between. In other words, the purpose of the link (network) is just to connect the two routers. There is no need to assign a network address to this type of link."



Was your explaination about the cable of thousands of pairs of wire inside it (I can imagine case)or about the physical cable of one pair of wire inside it (I can not imagine case)?
 
Joined
Oct 20, 2003
Messages
1,625
zillah said:
...
But I can not imagine one physical cable (one pair of wire inside it) to connect only (because there are no other pairs of wire availabe to other parties) two specific parties, in two different countries.
...
Was your explaination about the cable of thousands of pairs of wire inside it (I can imagine case)or about the physical cable of one pair of wire inside it (I can not imagine case)?
No. In this day and age it is indeed difficult to imagine that there would be anything other than a cable with thousands of pairs of wire inside it and point-to-point was organised over virtual circuits.

Although in the case I cited, about the Scottish island, it is likely that the last n miles of cable was literally a dedicated physical cable given there was little else on the island other than goats and gulls. :)
 

zillah

Thread Starter
Joined
Jun 6, 2005
Messages
333
If I want to apply the definition below:

"A point-to-point link connects two routers without any other hosts or routers in between. In other words, the purpose of the link (network) is just to connect the two routers. There is no need to assign a network address to this type of link."

to my scenario between two companies in USA and Australia,,,I have to imagine that there is cable (with thousands of pairs inside it) passing through ocean from Australia to US,,,one of these thousnads of pair has been assigned to this connection,,,I can imagine this,,,,but can we satisfy that only the two routers in Sydney and US are connected to each other with no other routers in the way ?
 

zillah

Thread Starter
Joined
Jun 6, 2005
Messages
333
it is likely that the last n miles of cable was literally a dedicated physical cable
What about the rest,,,why did you except the last mile only ?
 
Status
This thread has been Locked and is not open to further replies. Please start a New Thread if you're having a similar issue. View our Welcome Guide to learn how to use this site.

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

As Seen On
As Seen On...

Welcome to Tech Support Guy!

Are you looking for the solution to your computer problem? Join our site today to ask your question. This site is completely free -- paid for by advertisers and donations.

If you're not already familiar with forums, watch our Welcome Guide to get started.

Join over 807,865 other people just like you!

Latest posts

Members online

Top