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RSVP
Resource Reservation Protocol (RSVP) is a protocol that hosts can use to request specific QoS
parameters through the network for a particular application data stream. A host can request
guaranteed service through a network. If all routers have RSVP support enabled, and if there
exists sufficient unreserved bandwidth, a reservation is established throughout the network. If
insufficient bandwidth exists, the reservation fails and notifies the hosts. At that point, hosts can
choose to send traffic without a reservation, or drop the connection.
RSVP is supported in Communication Manager beginning with Release 1.3. RSVP can be
enabled per network region on the network region form. If RSVP is enabled, endpoints including
IP Telephones and media processors attempt to establish a reservation for each call. If the
reservation fails, Avaya endpoints still try to place a call, but lower the DiffServ priority of the call
to the better-than-best-effort (BBE) DSCP that is defined on the network region form. By default,
this value is 43.
If RSVP is enabled on a network region, it is very important that it also be enabled on
associated routers. If not, all RSVP reservations fail, and all voice traffic in that region is marked
with the BBE DSCP, which will generally receive degraded service versus the EF (DSCP 46)
DiffServ Code Point.
Table 74: Original TOS specification (continued)
Bit
Value
description
Bit 4
0
Throughput
1
Bit 5
0
reliability
1
Bit 6
0
monetary cost
1
Bit 7
reserved
Use
Normal
High
Normal
High
Normal
Low
Always set to 0
2 of 2
Issue 3.4.1 June 2005
RSVP
319
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