Sonora Communications, Inc.

Common Types of Internet Connections Explained

This page is intended to explain a few points about common types of Internet connections you might be considering. 

Also, we point out a few issues concerning virtual private network (VPN) connections as they relate to choosing your Internet access service.  VPN connections over the Internet constitute an important and growing factor in choosing Internet access service.

Dialup

• Dialup connections use analog modems to connect
  • modems modulate, then demodulate a digital datastream
    • convert from digital to analog, then back again
  • modulated datastream is transferred over voice network
  • voice network was never intended to tranfer data
  • phone company does not support data over voice circuits
• very limited bandwidth - typically 40kbps
• occupies phone line when connection is made
• connections are slow to come up
• connections are intermittent

DSL

• point to point connection to service provider (ISP)
• ADSL
  • most common and least expensive
  • slower uplink than downlink
  • not good for VPNs
  • not good for servers (web servers, FTP servers, etc.)
  • tech support generally poor
  • generally good for
    • non-critical/residential use
    • single-user/light use
• SDSL
  • slightly more expensive
  • same uplink and downlink speeds
  • generally better back-end infrastructure
  • generally more business-oriented
  • better for servers
  • better for VPNs
  • generally better (business-oriented) support
  • better for multiple users

Cable

• shared connection to ISP
  • shared with 1022 of your closest neighbors (typical)
• much slower uplink than downlink
• performance often varies widely
• servers generally not permitted
• common TCP/IP ports often blocked (25, 80, etc.)
• tech support generally poor
• generally fast download (browsing) performance
• generally good for
  • non-critical/residential use

Leased Line

• generally T1 (1.5mbps) or fractional T1 (FT1)
• point to point connection to ISP
• high reliability
• generally best for servers
• best service level guarantees
• much better support
• generally very low latency (round-trip times)
• some new-style connections use (ATM) DSL infrastructure
  • not the same as normal T1 connection
  • service guarantees usually lower
  • less expensive

Choosing Internet Connections for VPN Use

• avoid asynchronous services
  • ADSL or cable
  • they will severly limit VPN performance
• SDSL and Leased Line connections are greatly preferred
  • generally same uplink/downlink speeds
  • generally lower latency (important for VPNs)
  • generally better support
  • generally better back-end infrastructure
  • generally better service guarantees