RSVP Message 解析
RSVP supports the following messages:
1. Path message(PATH):
An RSVP path message is sent by each sender along the unicast or multicast routes provided by the routing protocol. A path message is used to store the path state in each node. The path state is used to route reservation-request messages in the reverse direction.
2. Reservation-request message(RESV):
A reservation-request message is sent by each receiver host toward the senders. This message follows in reverse the routes that the data packets use, all the way to the sender hosts. A reservation-request message must be delivered to the sender hosts so that the hosts can set up appropriate traffic-control parameters for the first hop. RSVP does not send any positive acknowledge messages.
"Each Reservation is Unidirectional"
3. Error and confirmation messages:
Reservation-request acknowledgment messages are sent as the result of the appearance of a reservation-confirmation object in a reservation-request message. This acknowledgment message contains a copy of the reservation confirmation. An acknowledgment message is sent to the unicast address of a receiver host, and the address is obtained from the reservation-confirmation object. A reservation-request acknowledgment message is forwarded to the receiver hop by hop to accommodate the hop-by-hop integrity-check mechanism.
- Path-error message result from path messages and travel toward senders. Path-error messages are routed hop by hop using the path state. At each hop, the IP destination address is the unicast address of the previous hop.
- Reservation-request error messages result from reservation-request messages and travel toward the receiver. Reservation-request error messages are routed hop by hop using the reservation state. At each hop, the IP destination address i the unicast address of the next-hop node. Information carried in error message can include the following:
4. Teardown:
RSVP teardown messages remove the path and reservation state without waiting for the cleanup timeout period. Teardown messages can be initialed by an application in an end system (sender or receiver) or a router as the result of state timeout. RSVP supports the following two types of teardown messages:
- path-teardown: Path-teardown message delete the path state (which deletes the reservation state), travel toward all receivers downstream from the point of initiation, and are routed like path messages.
- reservation-request teardown: Reservation-request teardown messages delete the reservation state, travel toward all matching senders upstream from the point of teardown initiation, and are routed like corresponding reservation-request messages.
1. Path message(PATH):
An RSVP path message is sent by each sender along the unicast or multicast routes provided by the routing protocol. A path message is used to store the path state in each node. The path state is used to route reservation-request messages in the reverse direction.
2. Reservation-request message(RESV):
A reservation-request message is sent by each receiver host toward the senders. This message follows in reverse the routes that the data packets use, all the way to the sender hosts. A reservation-request message must be delivered to the sender hosts so that the hosts can set up appropriate traffic-control parameters for the first hop. RSVP does not send any positive acknowledge messages.
"Each Reservation is Unidirectional"3. Error and confirmation messages:
Reservation-request acknowledgment messages are sent as the result of the appearance of a reservation-confirmation object in a reservation-request message. This acknowledgment message contains a copy of the reservation confirmation. An acknowledgment message is sent to the unicast address of a receiver host, and the address is obtained from the reservation-confirmation object. A reservation-request acknowledgment message is forwarded to the receiver hop by hop to accommodate the hop-by-hop integrity-check mechanism.
- Path-error message result from path messages and travel toward senders. Path-error messages are routed hop by hop using the path state. At each hop, the IP destination address is the unicast address of the previous hop.
- Reservation-request error messages result from reservation-request messages and travel toward the receiver. Reservation-request error messages are routed hop by hop using the reservation state. At each hop, the IP destination address i the unicast address of the next-hop node. Information carried in error message can include the following:
- Admission failure
- Bandwidth unavailable
- Service not supported
- Bad flow specification
- Ambiguous path
4. Teardown:
RSVP teardown messages remove the path and reservation state without waiting for the cleanup timeout period. Teardown messages can be initialed by an application in an end system (sender or receiver) or a router as the result of state timeout. RSVP supports the following two types of teardown messages:
- path-teardown: Path-teardown message delete the path state (which deletes the reservation state), travel toward all receivers downstream from the point of initiation, and are routed like path messages.
- reservation-request teardown: Reservation-request teardown messages delete the reservation state, travel toward all matching senders upstream from the point of teardown initiation, and are routed like corresponding reservation-request messages.
Comments