Technical Summary
This Informational document describes service classes configured with
Diffserv, and recommends how they can be used and how to construct them
using Differentiated Service Code Points (DSCP), traffic conditioners,
Per-Hop Behaviors (PHB), and Active Queue Management (AQM) mechanisms.
There is no intrinsic requirement that particular DSCPs, traffic
conditioners, PHBs, and AQM be used for a certain service class, but
as a policy and for interoperability it is useful to apply them
consistently.
Working Group Summary
The working group quickly determined that this document should
be Informational rather than a BCP. There were other significant
working group review issues, but the discussions did not entail
major controversy.
Protocol Quality
A directed review of the document was conducted in the working
group with written reviews invited from Brian Carpenter, as one
of the Chairs of the former Diffserv WG, Alan O'Neill, as an
expert on mobile multimedia, and David Black, as an expert on
Diffserv, but also diverse applications and security aspects.
Revisions followed these reviews. For the Working Group Last
Call of the document, a request was sent to many working groups
representing application or other areas, asking them to take
another look. These groups included MPLS, DCCP, the Routing Area
WG, SIPPING and AVT. Some comments were received and addressed
in the final revision.
James Polk is the WG Chair shepherd. Allison Mankin is the
Responsible Area Director.
Notes to the RFC Editor
Section 3.2, Network Control Service Class
OLD:
Traffic characteristics of packet flows in the Network Control
service class:
o Mostly messages sent between routers and network servers
o Ranging from 50 to 1,500 byte packet sizes, normally one packet at
a time but traffic can also burst (BGP)
NEW:
Traffic characteristics of packet flows in the Network Control
service class:
o Mostly messages sent between routers and network servers
o Variable size packets, normally one packet at a time but traffic
can also burst (BGP)
Section 3.3, OAM Service Class:
OLD:
Traffic characteristics:
o Variable size packets (50 to 1500 bytes in size)
NEW:
Traffic characteristics:
o Variable size packets
Section 4.2, Signaling Service Class
OLD:
Traffic characteristics:
o Variable size packets (50 to 1500 bytes in size)
NEW:
Traffic characteristics:
o Variable size packets, normally one packet at a time
Section 4.4, Real-time Interactive Service Class
OLD:
Traffic characteristics:
o Variable size packets (50 to 1500 bytes in size)
NEW:
Traffic characteristics:
o Variable size packets
Section 4.7 Low Latency Data Service Class
OLD:
Traffic characteristics:
o Variable size packets (50 to 1500 bytes in size)
NEW:
Traffic characteristics:
o Variable size packets
Section 4.8, High Throughput Data Service Class
OLD:
Traffic characteristics:
o Variable size packets (50 to 1500 bytes in size)
NEW:
Traffic characteristics:
o Variable size packets
Section 1.5.5, Admission Control
OLD:
Since RTP voice does not react to loss or delay in any
substantive way, the network SHOULD police at ingress to
ensure that the voice traffic stays within its negotiated bounds.
NEW:
Many RTP voice payloads are inelastic and cannot react
to loss or delay in any substantive way. For these
voice payloads, the network SHOULD police at ingress to
ensure that the voice traffic stays within its negotiated
bounds.
Section 4.1, Telephony Service Class
OLD:
Since RTP telephony flows do not react to loss or substantial
delay in any substantive way, the Telephony service class
SHOULD forward packet as soon as possible.
NEW:
Since the inelastic types of RTP payloads in this class
do not react to loss or significant delay in any substantive
way, the Telephony service class SHOULD forward packets as
soon as possible. Some RTP payloads that may be used in
telephony applications are adaptive and will not be in
this class.