Frequently Asked Questions


  1. What is the difference between SDSL and ADSL ?
  2. Bell Atlantic has great ADSL Pricing,  Why shouldn't I   subscribe?
  3. I got a competitive quote, Will RapidDSL  match it?
  4. Why Not RapidDSL ?
  5. Should I use a Tier 1 provider ?
  6. Do Tier 1 providers offer small businesses better performance?
  7. What are cable modems?
  8. What is over subscription ?
  9. What is a safe oversubscription rate?
  10. What Speed Do I need?
  11. Is Firewall protection available using DSL?
  12. How many IP Addresses can I have?

SDSL vs ADSL

    SDSL stands for synchronous digital subscribers line.   Synchronous means that data is sent to the Internet (uplink) and received from the Internet (downlink) at the same speed..  This is ideal for business class solutions that provide as well as receive data,  such as internal mail servers, web hosting, video conferencing, and remote LAN access.  Because SDSL is marketed towards businesses, SDSL networks utilize higher grade equipment and typically are monitored more closely.  SDSL provides dedicated bandwidth across a virtual circuit.

    ADSL stands for asynchronous digital subscribers line. Asynchronous means that data is sent and received at different speeds.  Downlink speeds are high, so web browsing is lightning quick.  Because uplink speeds are much slower,   ADSL is most suitable to fill the needs of residential users.  Because ADSL is marketed towards residential markets, the primary goal is to make the connectivity cheap. It is assumed that ADSL will be used by clients much less consistently, and therefore the over subscription rate on ADSL networks are much higher. Bandwidth is not guaranteed, and performance should be expected to decrease during peak usage times.

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Cheap Bell Atlantic ADSL, Why Shouldn't I subscribe?

It is true that companies such as Bell Atlantic offer residential ADSL circuits at rock bottom prices.  This fills the need for many residential users, where price is most important and reliability is not needed.  This service uses dynamic IP assignment. This means that each time you connect to the Internet you will be issued a new different IP address on the Internet.  This is not acceptable if,  (1) you need to pass through a corporate firewall, or if (2) your PC needs to be available to the Internet for hosting applications such as remote access, personal website or Internet telephone applications.  Bell Atlantic.net require proprietary dial-up software reducing options.  Bell Atlantic InfoSpeed DSL is a CLEC, where as Bell Atlantic.net is the ISP.  Make sure advertised pricing includes combined services.  RapidDSL's ADSL is available now in many areas where Bell Atlantic is not yet available.

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I have a competitive Quote, will RapidDSL match it ?

Yes.  RapidDSL will often match competitive quotes based on an apples to apples comparison.  In general, RapidDSL is not trying to be the lowest price in town. If anything, we are attempting to charge a little bit more, because we offer more.  If we consistently charged less than our competitors, we would not be able to provide the higher level of support and services that have elevated us above our competition.  We cater to the percentage of the population that understands that there is more to connectivity than just price.

    In order to receive a price match, the client must fax over a copy of their competitive bid contract stating all terms and conditions of represented services.  RapidDSL's SDSL price match service runs on a secondary network and may have a higher oversubscription rate.  Client side Real Time Monitoring is not included.  The client will still be able to take advantage of our fault tolerant servers and superior technical support..

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Why not RapidDSL ?

We can't think of a reason why not.  We offer better reliability, better support, and easier maintenance.  What more could a business client want?  If you can think of something, let us know, and we'll do our best to fix it..

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Should I use a Tier 1 Provider ?

No.  Tier 1 providers are high volume, minimal support, bandwidth distributors, typically targeting ISPs and corporations with large technical staff.  Small businesses require the flexibility, value added services, and personal care of a smaller Tier 2 or Tier 3 Internet provider.

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Do Tier 1 providers offer small businesses better performance ?

No.  Typically small businesses with low bandwidth needs (under 1.6 Mb),  are put several levels deep on their tier1 providers network, equivalent to the performance of tier 2 or tier 3 providers, and are susceptible to the same oversubscription bottlenecks.  RapidDSL's SDSL connectivity option guarantees bandwidth. 

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What are Cable Modems  ?

Cable modems are a cost effective way for residential users to access the Internet through their existing cable TV wire. Cable Modems have high downlink speeds for web browsing. Cable modems are not distant sensitive and service is usually available anywhere cable TV is available.  Cable modems have two major disadvantages.  You share the same cable segment as your neighbors. The more neighbors that utilize the service, the slower it gets.  Secondly, their are security concerns, since your data is running unsecured along side your neighbors' data.    

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What is over subscribing ?

   Over subscription is the practice of selling more circuit bandwidth coming from clients in to the ISP than bandwidth going out to the Internet.  This of course creates a bottleneck at the ISP.  In general, a client's speed is only as quick as the slowest link.  Usually, if you're getting an unbelievable price, you are usually also getting a higher over subscription rate.

    ADSL can have a higher oversubscription rate with fewer penalties, because it is assumed that residential circuits (single IP, single PC accounts) will be utilized less frequently.  Business SDSL accounts on the other hand, are already sharing (oversubscribing) their circuit bandwidth internally between all Office PCs.  In many cases, the client's SDSL circuit may already be consistently utilized near capacity. This is why Business SDSL should not be oversubscribed at the ISP.  High oversubscription rates will lead to slow performance, unreliable mail delivery, and lost data packets.  

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What is a safe oversubscription   rate?

A network on average should never reach 75% of its capacity. Doing so will start to reduce performance, and in many cases start to loose data packets.  Bandwidth is dedicated through the CLEC to the ISP. Once at RapidDSL, bandwidth is guaranteed my monitoring the overall performance of the network.  Our network backbone averages below fifty (50%) percent of its capacity.  If average bandwidth peaks approach 75%, we automatically upgrade our backbone bandwidth.  

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What speed do I need ?

You are only as fast as your slowest bottleneck.  Typically, Internet web servers rarely deliver data across the Internet to the client above 384K.  Therefore 384K is more than adequate for a single PC.  Businesses need more bandwidth.  PCs in the office are rarely connecting to the same web servers.  Therefore, if three PCs were connecting to three different sites, 1100KB could be utilized.  In general though, even if three PCs were being used at the same time, they would rarely use their bandwidth potential, because users need time to read and navigate thier screens.  Peer to peer live video, gaming, WAN office connectivity can quickly saturate high speed lines.   Subscribing to the slowest 144K SDSL circuit will still offer an improvement over ISDN to any small business.  RapidDSL recommends starting at 384K for up to 15 PCs,   768K for up to 25 PCs, and 1100KB for larger companies or high volume networks.  

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Is Firewall protection available using DSL ?

   YES. Unlike other DSL providers, RapidDSL allows control of the DSL router to be taken by the client or RapidDSL.  This allows for cost effective, yet powerful router based firewall solution, saving thousands of dollars.  Other DSL providers usually restrict the clients access to the router, allowing the customer to only use costly external PC firewalls, or less flexible external proxy servers.

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How many IP addresses can I have ?

   IP address are always available as needed  on SDSL circuits.   Typcally144k-192k connections get assigned a 16 address subnet.  SDSL 384K and up are not limited.  ADSL circuits are marketed to individuals and there for only get a single static IP address.  Multiple PCs can share an ADSL circuit using network address translation.   

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Copyright RapidDSL. All rights reserved.
Revised: August 10, 2000.