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What is SNR Margin and Line Attenuation?

The SNR margin is the Signal to Noise Ratio margin. Signal to Noise Ratio is the relation between the data signal level and the noise level. Even the most perfect cable absorbs some noise. This "...
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11 votes
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Why is the Ethernet Connection Symmetric?

The very first Ethernet standards were designed for using a single, shared coax wire. There's no benefit in making the connection asymmetric in any way. Additionally, network nodes are generally ...
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10 votes

Why use PPPoE and not use IP directly?

A few reasons. Firstly that is just the way it has always been and ISPs are loath to change a working setup. Secondly it's possible to create translators between different types of PPP. Just because ...
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9 votes

Why is the Ethernet Connection Symmetric?

Q: Why is ethernet symmetric (when compared to ADSL's asymmetry). A: This is best explained by looking the technical reason for ADSL's asymmetry. Quoting directly from wikipedia: There are both ...
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8 votes

Why use PPPoE and not use IP directly?

Yes, the "E" in PPPoE stands for ethernet. The PPP stands for Point-to-Point Protocol. PPPoE and PPPoA are often used with DSL. PPP was the original protocol which was allowed by the DSL Forum. PPP ...
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8 votes
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does the DSL distance really add more latency

Twisted pair cable used for the local loop has a velocity factor of about .58 - each km of cable takes ca. 6 µs to travel, adding ca. 12 µs to latency. The rest of the Internet probably uses fiber ...
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8 votes
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ISDN and DSL comparison

You can't really compare those two technologies. ISDN is a network protocol encompassing practically the whole OSI model from physical to application layer. xDSL is a family of physical-layer line ...
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6 votes
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Leased lines vs. bonded DSL

You need to check a few things; DSL is an aggregation technology which is normally on 'shared' media (you will be sharing with other, both the media to the point of presence and aggregation devices ...
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6 votes
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PPPoE interface doesn't use ARP

PPP doesn't use MAC addresses or ARP the way ethernet does, so no, there will not be ARP in PPP, but there may be ARP in the ethernet which carries the PPP frames. You will not see anything ethernet-...
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6 votes

Is it possible to set up a DSL lab environment?

If I have a switch or laptop running a PPPOE server, could I go from ethernet-to-modem then connect the modem's WAN port to another modem's WAN port and have it connect via PPPOE? No. A DSL modem is ...
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5 votes

What causes packet loss when using full bandwidth from ISP?

There are a number of possibilities here, not limited to, but including: The CPE's CPU is maxing out. (CPE=Customer Premesis Device) Check the specifications for the router you are using to make ...
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5 votes
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Simple question: Cisco 1750 AUX Port as "ADSL WIC"

The first diagram will not work, and in fact may result in damage to your router. The AUX port is a regular RS232 serial port, which is completely incompatible with ADSL. Don't do it. The second ...
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5 votes

What exactly is the local loop?

What is Local Loop? The portion of the telephone system that connects your home or office to the nearest central office (CO) of your local telco. The wiring used in the local loop is usually ...
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5 votes

Why is the Ethernet Connection Symmetric?

Ethernet is a local area network technology, and it was designed with no assumption that traffic will be higher in one direction than the other. It was developed long before the web or Internet was ...
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5 votes
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What are the reasons for ADSL to use ATM instead of Ethernet

According to the German Wikipedia the bit rates used in the time when ADSL was invented was the reason: At that time the backbones of the telephone and internet providers operated at 1-40 MBit/s ...
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5 votes
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VDSL2 Cross Talk

They are just all mixed together. No, they're not. Each pair must be kept together at all times; if you separate or recombine the single wires crosstalk goes through the roof and all is lost. ...
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4 votes

Cisco 877 ADSL Configuration

1) Have you asked your ISP to route the /29 public net to the dialer0 address that is assigned to your router via PPP\IPCP(Internet Protocol Control Protocol)? Once that is done then route the /29 ...
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4 votes

Will a network congestion occur if I use a single ADSL router connected to 24 port switch

The Ethernet connections are full duplex, and in this sense there shouldn't be usually problem on a path from end user to switch, and in most of the time, from switch to ADSL router. However, ...
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4 votes

Simple question: Cisco 1750 AUX Port as "ADSL WIC"

Except the 1750 only has one fastethernet port. A WIC-1ENET is 10m, WIC-4ESW a 4 port switch... but they both live on the WIC bus that'll top out about 6-8m. Depending on your DSL speed, this may not ...
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4 votes
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What's the difference of TR-069 and Point-To-Point protocol?

I think you are confused with the terms Point to Point and TR-069 here. An ISP normally uses IPOE/PPPOE/PPPOA for establishing the connectivity between CPE(Modem/Gateway) and their BRAS. They also ...
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4 votes
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Can a VDSL2 to Ethernet converter be used as a replacement for a bridging VDSL2 modem?

The particular device you have listed is required to be used as a pair. This is for someone who want to extend a network across voice cabling, or for a small ISP to use to connect to customers. It ...
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4 votes
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Best way to replace DSL cable by CAT6 cable

The DSL line runs for hundreds or even thousands of meters on plain telephone cable (Cat-3ish). A few meters of Cat-6 will change nothing to improve signal integrity. Just use any pair. Don't ...
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3 votes

Does Internet speed over cable depend on distance?

The answer to your question depends completely on the technology used. The complete answer to your question is far too broad, covering many different technologies, to answer here. Any distance will ...
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3 votes

Why many of our WANs use fixed bandwith division between up- and downstream?

I think you have missed something more fundamental that has lead you to ask your question, but in fact the question isn't really valid. ADSL isn't for hosting providers or people with large uploads ...
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3 votes
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Why many of our WANs use fixed bandwith division between up- and downstream?

One reason is that although it is possible to do dynamic frequency allocation, it is more resource intensive, and as a result more costly because it has to be negotiated on both sides, which leads to ...
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3 votes
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Link ADSL modem together

No. ADSL uses different upstream and downstream frequency ranges. As such, a modem is designed to transmit only in a narrow, low frequency range for which is has no receive capability. (The much ...
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