Traffic control functions only apply to integrated service and
are not specific to iSeries™.
You will not see these terms used in the quality of service (QoS)
interface, because the server cannot control external hardware. Outside a
private network, hardware needs to have the ability to handle general QoS
requirements. The general router requirements for IntServ policies are discussed
in the following section. It is suggested that you research general QoS concepts
and prerequisites before implementing policies.
To get predictable results, you need to have hardware that is enabled by
ReSerVation Protocol (RSVP), along the traffic's path. Routers must have certain
traffic control functions in order to use RSVP. This is often referred to
as being RSVP-enabled or QoS-enabled. Remember that your server's
role is either a client or a server. It cannot be used as a router at this
time. Check with your network equipment manuals, to verify that they can handle
QoS requirements.
Traffic control functions can include the following functions:
- Packet scheduler
- The packet scheduler manages the packet forwarding based on the information
in the IP header. The packet scheduler ensures that the packet delivery corresponds
to the parameters you set in your policy. The scheduler is implemented at
the point where packets are queued.
- Packet classifier
- The packet classifier identifies which packets of an IP flow will receive
a certain level of service based, again, on the IP header information. Each
incoming packet is mapped by the classifier into a specific class. All the
packets that are classified in the same class receive the same treatment.
This service-level is based on the information you provided in your policy.
- Admission control
- The admission control contains the decision algorithm that a router uses
to determine if there are enough routing resources to accept the requested
QoS for a new flow. If there are not enough resources, the new flow is rejected.
If the flow is accepted, the router assigns the packet classifier and scheduler
to reserve the requested QoS. Admission control occurs in each router along
the reservation path.