RFC 3772 (rfc3772) - Page 2 of 10

Point-to-Point Protocol (PPP) Vendor Protocol

RFC 3772                  PPP Vendor Protocol                   May 2004


   First, because it would be in LCP, the negotiation of the use of the
   protocol would begin before identification and authentication of the
   peer had been done.  This complicates the security analysis of the
   feature and constrains the way in which the protocol might be
   deployed.

   Second, where compulsory tunneling is in use, the system performing
   the initial LCP negotiation may be unrelated to the system that uses
   the proprietary protocol.  In such a scenario, enabling the protocol
   at LCP time would require either LCP renegotiation or support of the
   proprietary protocol in the initial negotiator, both of which raise
   deployment problems.

   Third, the fact that any protocol negotiated via such a mechanism
   would necessarily use a protocol number that is not assigned by IANA
   complicates matters for diagnostic tools used to monitor the
   datastream.  Having a fixed number allows these tools to display such
   protocols in a reasonable, albeit limited, format.

   A cleaner solution is thus to define a set of vendor-specific
   protocols, one in each of the four protocol number ranges defined by
   [1].  This specification reserves the following values:

   Value (in hex)  Protocol Name
   005b            Vendor-Specific Network Protocol (VSNP)
   405b            Vendor-Specific Protocol (VSP)
   805b            Vendor-Specific Network Control Protocol (VSNCP)
   c05b            Vendor-Specific Authentication Protocol (VSAP)

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in BCP 14, RFC 2119 [2].

2.  PPP Vendor-Specific Network Control Protocol (VSNCP)

   The Vendor-Specific Network Control Protocol (VSNCP) is responsible
   for negotiating the use of the Vendor-Specific Network Protocol
   (VSNP).  VSNCP uses the same packet exchange and option negotiation
   mechanism as LCP, but with a different set of options.

   VSNCP packets MUST NOT be exchanged until PPP has reached the
   Network-Layer Protocol phase.  Any VSNCP packets received when not in
   that phase MUST be silently ignored.  If a VSNCP packet with an
   unrecognized OUI is received, an LCP Protocol-Reject SHOULD be sent
   in response.






Carlson & Winslow           Standards Track