RFC 2210 (rfc2210) - Page 3 of 33
The Use of RSVP with IETF Integrated Services
Alternative Format: Original Text Document
RFC 2210 RSVP with INTSERV September 1997
- Information generated at each sender describing the data traffic
generated by that sender (the Sender TSpec). This information is
carried from the sender to intermediate network elements and the
receiver(s) by RSVP, but is never modified by intermediate
elements within the network. This information is carried in RSVP
SENDER_TSPEC objects.
- Information generated or modified within the network and used at
the receivers to make reservation decisions. This information
might include available services, delay and bandwidth estimates,
and operating parameters used by specific QoS control services.
this information is collected from network elements and carried
towards receivers in RSVP ADSPEC objects. Rather than carrying
information from each intermediate node separately to the
receivers, the information in the ADSPEC represents a summary,
computed as the ADSPEC passes each hop. The size of this summary
remains (roughly) constant as the ADSPEC flows through the
network, giving good scaling properties.
From the point of view of RSVP objects, the breakdown is as follows:
- The RSVP SENDER_TSPEC object carries the traffic specification
(sender TSpec) generated by each data source within an RSVP
session. It is transported unchanged through the network, and
delivered to both intermediate nodes and receiving applications.
- The RSVP ADSPEC object carries information which is generated at
either data sources or intermediate network elements, is flowing
downstream towards receivers, and may be used and updated inside
the network before being delivered to receiving applications.
This information includes both parameters describing the
properties of the data path, including the availability of
specific QoS control services, and parameters required by specific
QoS control services to operate correctly.
- The RSVP FLOWSPEC object carries reservation request
(Receiver_TSpec and RSpec) information generated by data
receivers. The information in the FLOWSPEC flows upstream towards
data sources. It may be used or updated at intermediate network
elements before arriving at the sending application.
NOTE: The existence of both SENDER_TSPEC and ADSPEC RSVP objects
is somewhat historical. Using the message format described in
this note it would be possible to place all of the service
control information carried "downstream" by RSVP in the same
object. However, the distinction between data which is not
updated within the network (in the SENDER_TSPEC object) and data
which is updated within the network (in the ADSPEC object) may
Wroclawski Standards Track