Browse Prior Art Database

Packet Fragmentation by Interface Hardware

IP.com Disclosure Number: IPCOM000114559D
Original Publication Date: 1995-Jan-01
Included in the Prior Art Database: 2005-Mar-29
Document File: 2 page(s) / 90K

Publishing Venue

IBM

Related People

Negishi, Y: AUTHOR [+2]

Abstract

Disclosed is a mechanism for enabling faster communications. It reduces communication overhead of operating systems without changing themselves. It only requires a modification on control program of a communication interface card to fragment a large packet to packets that is smaller than Maximum Transfer Unit, called MTU, on the sender side card, and to reassemble them to the original packet on the receiver side card.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 58% of the total text.

Packet Fragmentation by Interface Hardware

      Disclosed is a mechanism for enabling faster communications.
It reduces communication overhead of operating systems without
changing themselves.  It only requires a modification on control
program of a communication interface card to fragment a large packet
to packets that is smaller than Maximum Transfer Unit, called MTU, on
the sender side card, and to reassemble them to the original packet
on the receiver side card.

      General communication media's MTU is usually about 1 kilo
bytes, but users usually transfer larger packets, called "user
datagram", than the MTU.  In the case of Internet Protocol, the
maximum size of user datagram is 64 kilo bytes.  To transfer the user
datagram, the communication service part of operating systems divides
it to small packets whose size are smaller than MTU on the sender
side, and reassembles them to the user datagram on the receiver side.

      The point for enabling faster communication is to use a larger
size unit for a computer-card data transfer than one for
communication media.  Current communication systems use the same
size, but communication media's MTU (usually about 1 kilo bytes) is
too short to transfer data between a computer and its interface card,
much larger unit, such as 64 kilo bytes are preferable.  Usually data
are transferred between them by Direct Memory Access, called DMA.
DMA is a fast method to transfer large data, but it takes long time
for its...