Information Technology Reference
In-Depth Information
RSVP
The Resource Reservation Protocol (RSVP, RFC 2205) can be used in an integrated services architecture or a hybrid IntServ/DiffServ
architecture. Specifically, RSVP can be used to ensure that voice or other flows receive adequate QoS end to end across a network by
reserving resources on a hop-by-hop basis.
It is possible to specify different types of service via RSVP:
Controlled-load service (RFC 2211): Specifies a QoS level similar to that which would be received in an unloaded network
Guaranteed quality of service (RFC 2212): Specifies a QoS level that provides firm bounds on end-to-end queuing delays
On Cisco routers, it is possible to configure controlled-load, guaranteed-delay or best-effort service under a dial peer using the req-
qos and acc-qos commands. The req-qos command specifies requested QoS, and the acc-qos command specifies an acceptable QoS.
If the requested QoS is best effort, no bandwidth reservation takes place. However, if an RSVP reservation is attempted but fails, the
acceptable QoS is used to determine whether call setup goes ahead. If RSVP reservation fails, but acceptable QoS is set to best effort,
call setup goes ahead without any bandwidth reservation in the network. If RSVP reservation fails and acceptable QoS is not set to
best effort, call setup fails.
Other relevant RSVP IOS commands include the following:
ip rsvp bandwidth: Enables RSVP on a router or gateway interface.
call rsvp-sync: Enables synchronization between RSVP and voice signaling (for example, H.323).
call rsvp-sync resv-timer: Used to configure an RSVP reservation setup timer on the terminating voice gateway. The timer
is 10 seconds by default and begins when the terminating gateway receives an indication of an incoming call. If this timer
expires before RSVP setup is finished, the outcome of the call setup attempt depends on the configuration of the acceptable
QoS under the dial peer.
ip rsvp resource-provider [wfq-interface | wfq-pvc]: Used to configure WFQ as the resource provider on the interface/
PVC. This is used in an IntServ network architecture.
 
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