Originally posted by eddy_2790
Hey Giles, got a question for you. What is faster - DSL, Cable or Satellite?
The technologies are all capable of delivering quite large bandwidth, so the speed depends upon what you set it at. DSL and Cable can both deliver up to about 3Mb, and it's up to the ISP how they parcel this out. This is a physical limit of the cabling, in the same way that an analogue phone line is limited to 56Kb by its technology. Normally the connection in the exchange can handle a certain bandwidth, and then all the users connected to the exchange 'contend' for that bandwidth. When you buy a bandwidth-based package, the ISP will always say that it's the maximum-attainable, and that real world speeds may not represent this yada yada.
Some ISPs are using bandwidth-throttling on the exchanges to control the use of certain services, such as peer-to-peer file sharing like Bearshare or Kazaa. This is because these applications will typicall grab all the bandwidth available, and will choke the links. On the whole I'm in agreement with this policy as long as it's properly advertised and real technical information is available about it, so that customers can make an informed decision.
Satellite is a different matter, and it's not something I know too much about. I know that another company is using it to deliver DSL to a remote Scottish island, and they are getting download speeds consistent with a 512Kb connection. However, he couldn't answer my questions about latency, so he's going to come back to me on this one.
What's latency? It's the length of time it takes a signal to get from your machine to the target machine. It's also known as 'ping time', because the most common method of measuring this is by using ping. Want to measure your ping time? OK, open a DOS prompt, and if you're on 95/98/Me, type 'winipcfg'. Select your ISDN adapter, and look for your default gateway address. If you're on NT/2000/XP, type 'ipconfig /all' and look for the default gateway address. Now, go to the DOS prompt, and type 'ping' (without quotes) and the address of the default gateway. The response from the PING will give you the latency of your connection to your ISP. Obviously, the further you go from your ISP, the longer the latency as the signals have to go through more steps.
Here's what I get (I'm on Windows 2000, and I'm masking my IP address)
Code:
C:\>ipconfig /all
Windows 2000 IP Configuration
Host Name . . . . . . . . . . . . : talisker
Primary DNS Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Hybrid
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No
Ethernet adapter Local Area Connection:
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : 3Com EtherLink 10/100 PCI For
Complete PC Management NIC (3C905C-TX)
Physical Address. . . . . . . . . : 00-01-02-9D-00-2E
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
IP Address. . . . . . . . . . . . : xx.xxx.xx.xxx
Subnet Mask . . . . . . . . . . . : 255.255.255.128
Default Gateway . . . . . . . . . : 80.195.73.129
DHCP Server . . . . . . . . . . . : 62.31.64.115
DNS Servers . . . . . . . . . . . : 62.31.64.115
62.31.64.116
Lease Obtained. . . . . . . . . . : 28 September 2002 10:41:36
Lease Expires . . . . . . . . . . : 29 September 2002 08:26:24
C:\>ping 80.195.73.129
Pinging 80.195.73.129 with 32 bytes of data:
Reply from 80.195.73.129: bytes=32 time=41ms TTL=255
Reply from 80.195.73.129: bytes=32 time=20ms TTL=255
Reply from 80.195.73.129: bytes=32 time=10ms TTL=255
Reply from 80.195.73.129: bytes=32 time=10ms TTL=255
Ping statistics for 80.195.73.129:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 10ms, Maximum = 41ms, Average = 20ms
C:\>
Now, the latency for this connection is an average of 20ms, which means it takes 10ms for my ping to get to the gateway, and 10ms for it to get back.
Latency plus bandwidth give you your connection speed experience. If you're transferring large amounts of data in single transactions (i.e. downloads), then the bandwidth is the more significant parameter. But if you're playing an online game, then latency is the more significant parameter.
So to answer your question, Cable and DSL will be faster than satellite due to lower latency. But whichever has the higher bandwidth will be the fastest connection. However, you should watch for the 'contention ratio' (the number of people on the same exchange), as that can affect your speed too.
Sorry, went off on an explanation-rant. Hope it's useful!