RSVP Message Structure

RSVP was extended by various Requests for Comments (RFCs) to function as a signaling protocol to create Multiprotocol Label Switching (MPLS) LSPs. The signaling occurs with RSVP messages which are encapsulated directly with IP datagrams using a protocol ID of 46. Each RSVP message uses a common header followed by various objects, as shown in Figure 8.

Figure 8: RSVP Common Header

Table 13 lists and describes the fields in the RSVP common header.

Table 13: Fields in the RSVP Common Header

Field Name	Defined	Description
Version	4 bit	JUNOS software supports RSVP version 1.
Flags	4 bits Ox01 to 0x08 0x01: Refresh overhead reduction 0x02 to 0x08: Reserved	Used to signal support for protocol extensions to neighboring RSVP routers.
Message Type	1 Path (RFC 2205) 2 Resv (RFC 2205) 3 PathErr (RFC 2205) 4 ResvErr (RFC 2205) 5 PathTear (RFC 2205) 6 ResvTear (RFC 2205) 7 ResvConf (RFC 2205) 12 Bundle (RFC 2961) 13 Ack (RFC 2961) 15 SRefresh (RFC 2961) 20 Hello (RFC 3209) 25 Integrity Challenge (RFC 3097) 26 Integrity Response (RFC 3097)	Displays the number for the type of RSVP message encoded in the packet. For a detailed description of some message types, see Examining RSVP Log Messages and Examining RSVP Error Messages.
RSVP Checksum	16 bits	Displays a standard IP checksum for the entire RSVP message. When the checksum is computed, the local router assumes that this field contains zeros.
Send TTL	8 bits	Derived from the IP packet time to live (TTL). If the IP TTL value does not match the value in the Send TTL field, the previous node does not support RSVP.
Reserved	8 bits	This field is no used and must be set to 0x00.
RSVP Length	16 bits	Displays the entire RSVP packet, including any optional objects that are attached to the message.
Objects	Variable	This variable-length field contains one or more RSVP objects. For a more detailed description of objects, see RSVP Objects Structure.