blank.gif (43 bytes)

Church Of The
Swimming Elephant

Header Compression CPPP/CSLIP Connected: An Internet Encyclopedia
Header Compression CPPP/CSLIP

Up: Connected: An Internet Encyclopedia
Up: Topics
Up: Hardware
Up: Serial Links
Prev: SLIP Protocol Overview
Next: ISDN

Header Compression CPPP/CSLIP

Header Compression CPPP/CSLIP The Internet protocols introduce heavy overhead for some common types of network traffic. Probably the most extreme case is an interactive session with a user typing on a keyboard. With each keystroke, a packet is sent to the remote host and a reply is returned. Even though only a single byte of data is being sent, the addition of a TCP header (20 bytes) and an IP header (another 20 bytes) expand the resulting packet to at least 41 bytes. This represents 4000% overhead!

These problems are not apparent on Ethernet media, which enforces a 64-byte minimum size on all packets at the Data Link Layer. Other media may also be fast enough to disguise the problem, but dial-up modems can't tolerate such inefficiencies. RFC 1144 documents Van Jacobson compression, a popular technique for compressing TCP/IP headers. Van Jacobson compression can reduce packet header overhead from 4000% to 300%, enough to yield acceptable interactive performance at 2400 bps. This is often used in conjunction with SLIP or PPP, and referred to as CSLIP or CPPP.

  • Header, not data compression. Van Jacobson compression makes no attempt to compress the data portion of the packet.

  • End-to-end checksum. The original TCP checksum is always preserved, transmitted unmodified, and used to check the validity of the reconstructed packet. A sound case (the so-called end-to-end argument) can be made on the inherent robustness of this approach. Of course, the robustness is only as good as the checksum algorithm itself.

Next: ISDN

Connected: An Internet Encyclopedia
Header Compression CPPP/CSLIP


Protect yourself from cyberstalkers, identity thieves, and those who would snoop on you.
Stop spam from invading your inbox without losing the mail you want. We give you more control over your e-mail than any other service.
Block popups, ads, and malicious scripts while you surf the net through our anonymous proxies.
Participate in Usenet, host your web files, easily send anonymous messages, and more, much more.
All private, all encrypted, all secure, all in an easy to use service, and all for only $5.95 a month!

Service Details

Have you gone to church today?
All pages ©1999, 2000, 2001, 2002, 2003 Church of the Swimming Elephant unless otherwise stated
Church of the Swimming Elephant©1999, 2000, 2001, 2002, 2003 is a wholly owned subsidiary of Packetderm, LLC.

Packetderm, LLC
210 Park Ave #308
Worcester, MA 01609