Explain some of ADSL terms please.

Can someone please explain the following terms for me?

I have a DLink-300T modem and in the admin site there are a couple of setting that I don't completely understand.

1. Modulation Mode : MMODE,GLITE,GDMT,T1413. What is the difference and what setting works best for Telkom adsl?

2. Encapsulation : LLC or VC. What does this mean and do? Once again best setting for telkom?

3. PVC Settings : VPI,VCI, QoS->(UBR,CBR,VBR), PCRbps and SCRbps

We make multiple connections and I sometimes find that when there are say 2 connections that I'm not getting the normal speed with only 1 connection.
Can QoS have something to do with this?

Thanks in advance.

I only no some.
2. LLC is what you need for Telkom. Don't know wat is stands for, but google it youself?
3. VPI=8,VCI=35 (I think this identifies the ATM network (Backbone) to use. We only have Telkom, so everyone should have that the same. I can be mistaken)

Thanks

I hope some of the others are also explained, maybe in some more detail?

oober said:

1. Modulation Mode : MMODE,GLITE,GDMT,T1413. What is the difference and what setting works best for Telkom adsl?

Click to expand...

GLITE...but there should be an AUTO setting?

oober said:

2. Encapsulation : LLC or VC. What does this mean and do? Once again best setting for telkom?

Click to expand...

LLC...don't know what it means

oober said:

3. PVC Settings : VPI,VCI, QoS->(UBR,CBR,VBR), PCRbps and SCRbps

Click to expand...

Edit : VPI=8,VCI=35 (as mentioned)
The others...no idea...Sorry.

Got some more info:

Asynchronous Transfer Mode (ATM)---International standard for cell relay in which multiple service types (such as voice, video, or data) are conveyed in fixed-length (53-byte) cells. Fixed-length cells allow cell processing to occur in hardware, thereby reducing transit delays. ATM is designed to take advantage of high-speed transmission media such as E3, SONET, and T3.

Logical Link Control (LLC)---Higher of the two data link layer sublayers defined by the IEEE. The LLC sublayer handles error control, flow control, framing, and MAC-sublayer addressing. The most prevalent LLC protocol is IEEE 802.2, which includes both connectionless and connection-oriented variants.

virtual circuit (VC)---Logical circuit created to ensure reliable communication between two network devices. A virtual circuit is defined by a VPI/VCI pair, and can be either permanent (PVC) or switched (SVC). Virtual circuits are used in Frame Relay and X.25. In ATM terminology, a virtual circuit is also called a virtual channel.

permanent virtual circuit (PVC)---Virtual circuit that is permanently established. PVCs save bandwidth associated with circuit establishment and tear down in situations where certain virtual circuits must exist all the time. In ATM terminology, it is also called a permanent virtual connection.

Thanks for that info!

Now only the QoS=Quality of Service remains.
I did some googling and I found this article about QoS. Interesting thing is that what they call best-effort service
(rings a bell? Telkom says they provide a best effort service)
which means that we have no QoS management implemented in our ADSL network.

Also note that the article seems to imply that networks that uses the GLITE flavor of ADSL need a form of QoS since the bandwidth of GLITE networks are limited. This is just another example of Telkom milking the consumer market.

Anyway I'm gonna play around with these settings in the modem and see what it does.

What I found is that is seems that QoS is just plain old port shaping. And that we definetly do have as part of our ADSL. With QOS, you can give priority to applications & ports, bandwidth up/downstream limiting, MAC adress priority, etc.

Sounds like something that is implemented, just not named QOS?

oober said:

Also note that the article seems to imply that networks that uses the GLITE flavor of ADSL need a form of QoS since the bandwidth of GLITE networks are limited. This is just another example of Telkom milking the consumer market.

Click to expand...

Perhaps you should google better and read information with comprehension before drawing incorrect conclusions.

ADSL G.Lite allows for far GREATER distances from the exchange than normal ADSL and also does not require a splitter (cheaper for user) at the cost of lower line speed (2 Mbps vs 8Mbps).

This was the correct decision to make considering our infrastructure.