RFC 1046 (rfc1046) - Page 3 of 11
Queuing algorithm to provide type-of-service for IP links
Alternative Format: Original Text Document
RFC 1046 Type-of-Service Queuing February 1988
Applications for Class of Service
The following are examples of how classes of service might be used.
They do not necessarily represent the best choices, but are presented
only to illustrate how the different classes of service might be used
to advantage.
Interactive timesharing access using a line-at-a-time or character-
at-a-time terminal (TTY) type of access is typically low volume
typing speed input with low or high volume output. Some Internet
applications use echoplex or character by character echoing of user
input by the destination host. PC devices also have local files that
may be uploaded to remote hosts in a streaming mode. Supporting such
traffic can require several types of service. User keyboard input
should be forwarded with low delay. If echoplex is used, all user
characters sent and echoed should be low delay to minimize the
echoing delay. The computer responses should be regular or high
throughput depending upon the volume of data sent and the speed of
the output device. If the computer response is a single datagram of
data, the user should get low delay for the response, to minimize the
human/computer interaction time. If however the output takes a while
to read and digest, low delay computer responses are a waste of
Internet resources. When streaming input is being sent the data
should be sent requesting high throughput or regular class of
service.
The IBM 3270 class of terminals typically have traffic volumes
greater than TTY access. Echoplex is not needed. The output devices
usually handle higher speed output streams and most sites do not have
the ability to stream input. Input is typically a screen at a time,
but some PC implementations of 3270 use a variation of the protocol
to effectively stream in volumes of data. Low delay for low volume
input and output is appropriate. High throughput is appropriate for
the higher volume traffic.
Applications that transfer high volumes of data are typically
streaming in one direction only, with acks for the data, on the
return path. The data transfer should be high throughput and the
acks should probably be regular class of service. Transfer
initiation and termination might be served best with low delay class
of service.
Requests to, and responses from a time service might use low delay
class of service effectively.
These suggestions for class of service usage implies that the
application sets the service based on the knowledge it has during the
session. Thus, the application should have control of this setting
Prue & Postel