How did the misuse of the word bandwidth become so popular?

[Mucman]

It really irks me when I struggle through a class because the I learned the wrong definition of a word
from incorrect usage in forums and in the trade.

It makes sense that bandwidth is measured in Hz!!!! So the bandwidth of a network cable is such
and such MHz, and has a data rate of such and such Megabits...

Anyways, my data communications is kicking my arse right now and I just need to vent. How much more
respect for those adept at the physical layer now . The 6B/8T signal encoding is messing me up big time

 

[nightowl]

I know what you are talking about Muc. Bandwidth deals with frequencies and throughput is the bit rate of the transmission medium. I still use bandwidth when I am really referring to throughput.

 

[Mucman]

Originally posted by: nightowl
I know what you are talking about Muc. Bandwidth deals with frequencies and throughput is the bit rate of the transmission medium. I still use bandwidth when I am really referring to throughput.

Doesn't that annoy you though . Everytime I say bandwidth in the wrong context I cringe . It's like calling
those Linksys NAT boxes "Routers".

 

[Nothinman]

It's like calling those Linksys NAT boxes "Routers".

And why wouldn't they be, they route traffic between two networks, right?

 

[spidey07]

Not touching this one.

Oh, and don't "muc" with the physical layer.

 

[kehi]

spidey07:



lol

 

[JackMDS]

Originally posted by: spidey07


Not touching this one.

LOL

================================
Quote: "bandwidth is measured in Hz!!!!"

Why Hz? Hertz is a name of a Guy.

Heinrich Rudolf Hertz. Born and died in Germany 1857-1894.

Or may be we measure ?Bandwidth" with the Car Rental Company ?Hertz? :Q

We should refer to it as Cycle per Second. (C/sec. or cps) :light:

And speaking about Cars.

I guess that only Ferrari and Lamborghini can be called a Car, mine is probably ?Horseless Wagon?. :Q:brokenheart::disgust:

 

[cmetz]

Mucman, unfortunately, the FCC has written Internet-related regulations, most notably their definition of "broadband" (ugh), in terms of this abuse of the term bandwidth.. so it's here to stay. My personal background is as a EE specializing in communication systems, so you can see how the use of "bandwidth" to mean "bits/s" makes me cringe. It's extra, extra fun when you're developing a digital communication system (esp. RF based) where bandwidth can legitimately be used in both definitions to describe different ends of the system.

 

[JackMDS]

When I went for the EE in Electronic Communication, and Navigation (unfortunately this was more than 30 years ago) I was thought.

When a Transmitter is transmitting using 14MHz carrier the circuitry can not generate 14 MHz on the dot.

Bandwidth is the transmitted frequency from both sides of 14MHz that would be yielding signal up to 3db bellow the main signal. (Excuse me for the over simplification).

In other word if a strong signal is transmitted at 13.8MHz and 14.2MHz the bandwidth of this Transmitter is 14.2-13.8 = 400 KHz.

 

[Mucman]

Originally posted by: Nothinman

It's like calling those Linksys NAT boxes "Routers".

And why wouldn't they be, they route traffic between two networks, right?

No... they using IP masqing techniques, to connect remotely as one IP. It's more
of a proxy device in a way. Routing involved protocols like RIP, OSPF (is that right?), BGP
and I'm sure many others.

A NAT box involved IP MASQ. Technically the RFC1918 IP's are not supposed to be routable unless using an IP MASQing device.

Someone please correct me if I am wrong.

lolk @ spidey07

From now on I am going to refrain from the word bandwidth unless I mean it in the
proper context... Instead of saying that I have 100MBps of bandwidth at work, I will say
my work connection has a 100Mbps data rate

btw, this data communication course is fascinating stuff, unfortunately I got a crappy prof.
She doesn't make the 3 hour lecture interesting at all, and simply reads from her power point slide. It's a shame since I was really looking forward to this course.

Appropraite sig there JackMDS

 

[Nothinman]

No... they using IP masqing techniques, to connect remotely as one IP. It's more
of a proxy device in a way. Routing involved protocols like RIP, OSPF (is that right?), BGP
and I'm sure many others.

I know the difference between NAT and plain routing, but it's still connecting two different networks. And I don't think any automatic routing protocols are required, a router with all static routes is still a router.

 

[ScottMac]

I'll toss in a couple cents worth ....

The RFC addresses are perfectly good addresses, and they'll route just as good as any other IP address - internally. BY CONVENTION those addresses are filtered at the ISP's user-facing boundry routers. They will be filtered on their way to the Internet at the first ISP router they hit. They should also be filtered (it's recommended that they be filtered) on the outside interfaces of firewalls.


You can have a huge network of many LANs and WANs and never use a routing protocol. You CAN do it with all static routes ... it's just an administrative nightmare. The routing protocols (RIP v.I and v.II, OSFP, IS-IS, BGP, EIGRP, Etc) are administrative convieniences and provide "automatic" re-routing if a path fails and another path is available.

"Bandwidth," I believe, is a contextual term depending on the vernacular in-play. Bandwidth to a "radio Guy" is different than Bandwidth to a network guy (and of course it was bastardized by the business management to reflect available time for tasks).

Off the top of my head, in radio terms, bandwidth is the total spectrum used to propagate a given signal. I suppose that could apply to network signalling as well but, in the networking vernacular, it means the maximum amount of traffic a given medium will support, or a number representing how much of that maximum "space" a give traffic flow will deduct from the total.

Throughput is different than bandwidth: you can have a Gigabit-capable technology that only gets a few hundred meg of throughput. Thoughput represents the actual amount of traffic that makes it through, not the theoretical maximum.

I gotta go to work ... that's it (for now)

FWIW

Scott

 

[buleyb]

isn't there a misuse of broadband for many internet connections, when baseband really applies?


The thing to remember when it comes to terms, people are stupid and screw things up...and stupid propogates

 

[ITJunkie]

Originally posted by: spidey07


Not touching this one.

Oh, and don't "muc" with the physical layer.

LOL...totally

 

[martind1]

I dunno. I think I know the correct use of the word.

I post again when I am done bandwidthing my driveway.

 

[Mucman]

Originally posted by: Nothinman

No... they using IP masqing techniques, to connect remotely as one IP. It's more
of a proxy device in a way. Routing involved protocols like RIP, OSPF (is that right?), BGP
and I'm sure many others.

I know the difference between NAT and plain routing, but it's still connecting two different networks. And I don't think any automatic routing protocols are required, a router with all static routes is still a router.

ok, quick question... Let's say that your ISP has delegated you a /24 subnet. Can you
use your linksys box to route those IPs onto the Net? Can your hosts have non RFC1918
IP addresses using a Linksys device as your gateway?

Perhaps I am just been stubborn about the sophistication of the routing involved, and
saying that a NAT device is a router is something that's more subjective unlike the misuse
of the word bandwidth

Oh! And stop laughing at my name! It's like high-school all over again

 

[bwanaaa]

the whole nat thing is getting confusing-

when i have multiple windows of multiple browsers open (as well as other internet using apps) all the packets get to the right place. When each app sends a packet it opens a uniques port, sends the packet and lisens for the replly. Even though the pc only has 1 ip address, all the apps are sending and getting data. So why do we need different ip addresses anyway in a small network?

To extend this stupid and imaginary line of thought, couldnt linksys have made a 4 port 'router' in the following way- give a hundred unique ports to each rj45 jack on the back of the 'router'

 

[Mucman]

Originally posted by: bwanaaa
the whole nat thing is getting confusing-

when i have multiple windows of multiple browsers open (as well as other internet using apps) all the packets get to the right place. When each app sends a packet it opens a uniques port, sends the packet and lisens for the replly. Even though the pc only has 1 ip address, all the apps are sending and getting data. So why do we need different ip addresses anyway in a small network?

To extend this stupid and imaginary line of thought, couldnt linksys have made a 4 port 'router' in the following way- give a hundred unique ports to each rj45 jack on the back of the 'router'

The reason why each app gets its information properly is because of TCP/IP, and IP MASQ
is what makes it work in a NAT'ed enironment. Here's a mini summary of what happens :

Computer A does a request to anandtech.com
- Computer A browser (IE) makes a request to the remote IP on port 80.
- The packet is coming from an RFC1918 address and from a random port about 1024
- This packet is sent to the default gateway which is for this example a Linksys router.
- The Linksys router takes note of the internal IP, and the src port of the packet.
- It then replaces the src IP with the public IP of the router, and sends the packet on
to the next hop.
- The server receives the request, and sends it back. Note that the web-server only saw
the public IP address, so that is where the packet will be headed. The packet is returned
to the source port that made the request.
- Once the Linksys box receives the packet, it changes the packet headers again so that
destination machine is on the internal LAN. Keeping the destination port the same as the
source port that made the original request.
- Computer A receives the packet, and sends the appropriate packet data to the
application that made the original request on the destination port.

Hope that makes sense, and that if I got anything wrong, that someone will correct me As you can see, the IP MASQing takes effect when the Linksys box rewrites the packet header information changing the source ip address of the packet. For small networks, NAT
is definitely the way to go in many situations.

Not sure what you are saying about the Router with a 100 ports in it though

 

[Nothinman]

ok, quick question... Let's say that your ISP has delegated you a /24 subnet. Can you
use your linksys box to route those IPs onto the Net? Can your hosts have non RFC1918
IP addresses using a Linksys device as your gateway?

Honestly that's irrelevant, the fact that it's routing configuration is limited doesn't mean it doesn't have one. And some of the Linksys boxes run Linux, so I'm sure you could find a way to do whatever you wanted if you persisted.

Even though the pc only has 1 ip address, all the apps are sending and getting data. So why do we need different ip addresses anyway in a small network?

What happens when 2 people are listening for a reply on the same port? If we broadcast the replies both recieve the reply and one of them gets confused. An IP uniquely idenfies a machine on the network, a port is a unique identifier just on that one machine.

To extend this stupid and imaginary line of thought, couldnt linksys have made a 4 port 'router' in the following way- give a hundred unique ports to each rj45 jack on the back of the 'router'

That's a physical thing, all you would need to do is plug another switch into the router and all the machines in that switch should work fine.

 

[mboy]

Originally posted by: Mucman

Originally posted by: nightowl
I know what you are talking about Muc. Bandwidth deals with frequencies and throughput is the bit rate of the transmission medium. I still use bandwidth when I am really referring to throughput.

Doesn't that annoy you though . Everytime I say bandwidth in the wrong context I cringe . It's like calling
those Linksys NAT boxes "Routers".

That still isn't as bad as caling those Linksys NAT boxes FIREWALLS

 

[rfb]

Originally posted by: Mucman

Originally posted by: Nothinman

It's like calling those Linksys NAT boxes "Routers".

And why wouldn't they be, they route traffic between two networks, right?

No... they using IP masqing techniques, to connect remotely as one IP. It's more
of a proxy device in a way. Routing involved protocols like RIP, OSPF (is that right?), BGP
and I'm sure many others.

A NAT box involved IP MASQ. Technically the RFC1918 IP's are not supposed to be routable unless using an IP MASQing device.

Routing is the forwarding of a packet from one segment of a network to another. The Linksys NAT box does that, so it is a router. I also performs address translation in addition to routing.

RIP, OSPF and BGP are routing protocols (not to be confused with routing) which are used to maintain and update the routing tables within a router.

Roy

 

[Nothinman]

That still isn't as bad as caling those Linksys NAT boxes FIREWALLS

They could be if they'd let you edit the rules on the box, like I said a chunk of them run Linux so giving access to the iptables rule file shouldn't be that hard for them.

 

[CubanCorona]

Originally posted by: NothinmanWhat happens when 2 people are listening for a reply on the same port? If we broadcast the replies both recieve the reply and one of them gets confused. An IP uniquely idenfies a machine on the network, a port is a unique identifier just on that one machine.

This is something that I have often wondered about. Does anyone know for sure how that situation would work? Here's what I thought:

Since TCP sessions can not be initiated with a box on a NATed network from outside of that network (with the exception of a NAT router set up with port forwarding), it seems that a NAT router must keep track of more than just the source IP and port. If this is the case, then in an instance where two computers on the NATed network are waiting for a response on the same port, then the router will use the additional information to determine which box the packet is destined for. Additionaly it seems reasonable that IP MASQing replaces much more than the source and destination IP addresses. Consider this situation:

Boxes A and B are both on a NATed network using RFC1918 IPs. Both computers attempt to initate a TCP session with www.anandtech.com from the same port (1024)

[ A ]
[ 192.168.1.100 ] >> *1024 -> 80* [ NAT ROUTER ] >> *1024 -> 80*


[ B ]
[ 192.168.1.101 ] >> *1024 -> 80* [ NAT ROUTER ] >> *1025 -> 80*


It MUST be the case that the NAT router ALSO changes the source PORT since www.anandtech.com would be very confused if it received two separate requests to initate TCP sessions from the same port on the same IP.

I've got to run now, but hopefully someone can confirm or deny this (and do so in a bit more detail).

Willow

 

[Nothinman]

it seems that a NAT router must keep track of more than just the source IP and port.

The protocol is an important one, but a simple NAT implementation doesn't need much more.

It MUST be the case that the NAT router ALSO changes the source PORT since www.anandtech.com would be very confused if it received two separate requests to initate TCP sessions from the same port on the same IP.

Yes, the NAT box rewrites the from port in addition to the from IP address, it just remembers that packets coming back on X port go to Y machine on Z port.

There are also much more complicated ways of handling NAT in way that keeps state and understands stupid or complex protocols. Like FTP for instance, on Linux there is a module that understand the FTP procol and allows you to use PORT mode, when it sees a PORT command it rewrites it to use the Internet IP of the router then when data comes in on that port automatically forwards it back to the originating machine.

 

[Mucman]

Nothinman, I've thought about it a bit, and I now agree that those Linksys boxes can be called routers . Just very limited routers. I guess my argument
is similar to saying that Justin Timberlake is music