Network Working Group Steven J. Senum Request for Comments: Internet Draft Network Systems Corporation May 31, 1991 Point-to-Point Protocol Extensions for DECnet Phase IV Status of this Memo This draft document will be submitted to the RFC editor as a protocol specification. Please send comments to the author. It is an extension of the Internet Point-to-Point Protocol described in RFC 1171 [1], targeting the use of Point-to-Point lines for DECnet. Distribution of this memo is unlimited. 1. Introduction The purpose of this memo is to define a method for transmitting DNA Phase IV Routing packets over a serial link using the PPP protocol as defined in [1]. This memo only applies to DNA Phase IV Routing messages (both data and control), and not to other DNA Phase IV protocols (MOP, LAT, etc). There are two basic approaches to running the DNA Phase IV Routing protocol over a serial line: 1. The approached that several router vendors have taken which is to treat the serial link as an Ethernet, using the same data and control messages an Ethernet would use. 2. The approach defined by Digital, which uses DDCMP and slightly different control messages. This memo will define a method that uses the first approach. 2. Overview Of Phase IV DNA Protocols The Phase IV DNA protocols which act as data link clients are: o DNA Phase IV Routing The Phase IV Digital Network Architecture (DNA) Routing protocol is a network layer protocol providing services similar to that of DoD IP. It routes messages in Phase IV DECnet Senum [Page 1] Internet Draft DECnet Point-to-Point May 31, 1991 networks and manages the packet flow. The complete definition of the DNA Phase IV Routing protocol can be found in [2]. o DNA System Console The Digital Network Architecture (DNA) System Console protocol is a maintenance protocol providing low level access to a system for the functions of: . Identify processor . Read data link counters . Boot system . Console carrier (a general purpose i/o channel) The complete definition of the DNA System Console protocol can be found in [3]. o Digital Customer Use The Digital Customer Use protocol type is a value reserved for use by Digital customers. It allocates a type for private use which will not conflict with Digital or other vendor protocols. o DNA Diagnostics The Digital Network Architecture (DNA) Diagnostics protocol type is reserved to allow diagnostic software communications in parallel with other data link clients. o DNA Naming Service (DNS) The Digital Network Architecture Naming Service (DNS) provides a distributed naming service. It allows clients to register named objects and to bind a set of attributes to the objects in a distributed database. o DNA Time Service (DTS) The Digital Network Architecture Time Service (DTS) is a protocol providing global clock synchronization in a distributed environment. o DNA Load/Dump The Digital Network Architecture (DNA) Load/Dump protocol is a maintenance protocol for copying the contents of processor memory to or from a remote system. For example, a system manager can load an operating system into an unattended, remote system. The complete definition of the Phase IV DNA Load/Dump protocol can be found in [3]. o DNA Experimental Use The Digital Network Architecture (DNA) Experimental Use protocol type allows Digital experimental protocols to share a Senum [Page 2] Internet Draft DECnet Point-to-Point May 31, 1991 data link with other data link clients. It is for use by Digital Equipment Corporation only. o DNA Communications Test The Digital Network Architecture (DNA) Communications Test protocol is a maintenance protocol for testing the data link communications path. The complete definition of the DNA Communications Test protocol can be found in [3]. o Digital Protocol X1 The Digital X1 protocol is a network layer protocol currently private to Digital. 3. A PPP Network Control Protocol for DNA Phase IV Routing The DNA Phase IV Routing Control Protocol (DNCP) is responsible for configuring, enabling, and disabling the DNA Phase IV Routing protocol modules on both ends of the point-to-point link. As with the Link Control Protocol (LCP, defined in [1]), this is accomplished through an exchange of packets. DNCP packets may not be exchanged until the LCP has reached the Network-Layer Protocol Configuration Negotiation phase. DNCP packets received before this phase is reached should be silently discarded. Likewise, DNA Phase IV Routing packets may not be exchanged until the DNCP has first opened the connection (reached the Open state). The DNCP is the same as the LCP with the following exceptions: Data Link Layer Protocol Field Exactly one DNCP packet is encapsulated in the Information field of PPP Data Link Layer frames where the Protocol field indicates type hex 8027 (DNA Phase IV Control Protocol). Code field Only Codes 1 through 7 (Configure-Request, Configure-Ack, Configure-Nak, Configure-Reject, Terminate-Request, Terminate-Ack and Code-Reject) are used. Other Codes should be treated as unrecognized and should result in Code-Rejects. Timeouts DNCP packets may not be exchanged until the LCP has reached the network-layer Protocol Configuration Negotiation phase. An implementation should be prepared to wait for Link Quality testing Senum [Page 3] Internet Draft DECnet Point-to-Point May 31, 1991 to finish before timing out waiting for a Configure-Ack or other response. It is suggested that an implementation give up only after user intervention or a configurable amount of time. 3.1. DNA Phase IV Control Protocol Configuration Option Types The value for the Configuration Option Type field is 1 Node Type 3.1.1. Node Type Description This Configuration Option provides a way to ascertain the routing type of the nodes connected by the link. If a router discovers it is connected to an endnode, then the router may choose not to send routing update messages over this link. If this Configuration Option is rejected, the router should assume the other end of the link is a Level 2 Router. A summary of the Configuration Option format is shown below. The fields are transmitted from left to right. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Routing Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type 1 Length 4 Routing Type 1 Level 2 Router 2 Level 1 Router 3 Endnode Senum [Page 4] Internet Draft DECnet Point-to-Point May 31, 1991 4. Sending DNA Phase IV Routing Packets Before any DNA Phase IV Routing packets may be sent, both the Link Control Protocol and the DNA Phase IV Routing Control Protocol must reach Open state. Exactly one octet-count field and one DNA Phase IV Routing packet are encapsulated in the information field of PPP Data Link Layer frames where the Protocol field indicates type hex 0027 (DNA Phase IV Routing). The octet-count contains a count of the number of octets in the DNA Phase IV Routing packet. It is two octets in length itself, and is stored in VAX byte ordering, to be more consistent with DNA Phase IV Routing over Ethernet (i.e. least significant byte first). It is needed to disambiguate optional padding octets from real information. The maximum length of an DNA Phase IV Routing packet transmitted over a PPP link is the same as the maximum length of the Information field of a PPP data link layer frame minus 2 octets (for the Length field). The format of the packets themselves is the same as the format used over Ethernet, without the Ethernet header, Pad, and FCS fields. A summary of the information field is shown below. The fields are transmitted from left to right. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Length LSB | Length MSB | DATA | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Length LSB Least significant byte of length field Length MSG Most significant byte of length field DATA DNA Phase IV Routing data, as specified in [2] Senum [Page 5] Internet Draft DECnet Point-to-Point May 31, 1991 5. Other considerations When a topology change in the network occurs, DNA Phase IV Routing nodes immediately propagate changes via Level 1 and Level 2 Routing messages, with a 1 second minimum delay between updates. DNA Phase IV Routing nodes also periodically retransmit the complete Level 1 and Level 2 distance vectors to guard against data corruption in host memory, and (in the case of Ethernet) loss of packets due to media errors. Because Digital's serial links run a protocol that guarantees delivery of packets (DDCMP), the recommended default retransmit time is long (600 seconds), whereas for Ethernet, where packet delivery is not guaranteed, the recommended default is short (10 seconds). To achieve convergence of routes within a satisfactory time, the interval between updates should be based upon the error rate of underlying data link. The following values are guidelines by Digital for the routing update timer on unreliable links: o For bit error rates greater than 1 in 10^7, a reliable protocol (e.g. HDLC) may have to be used instead of PPP to achieve acceptable performance. o For bit error rates between 1 in 10^7 and 1 in 10^9, complete routing updates should be sent every 10 seconds. o For bit error rates less than 1 in 10^9, complete routing updates should be sent every 30 seconds. o Phase IV Routing should not be run over links of speed less than 56 Kbits per second. This will ensure that routing updates will never consume more that 3% of the nominal link bandwidth. Note that acceptable performance is also based on how often topology changes occur in the network, the size of the routing vectors, and what the network user is willing to tolerate. It is also recommended that the time between routing updates be user configurable per PPP interface. The Hello timer and Listen timer should be set according to the recommendations for broadcast links (15 and 45 seconds, respectively). Routers are not required to send routing updates if the remote node connected via the PPP link is an endnode. Endnodes are required to discard all routing updates received over a PPP link. Senum [Page 6] Internet Draft DECnet Point-to-Point May 31, 1991 References [1] Perkins, D., "The Point-to-Point Protocol for the Transmission of Multi-Protocol Datagrams Over Point-to-Point Links", RFC 1171, Carnegie Mellon University, July 1990. [2] Digital Equipment Corporation, "DNA Routing Layer Functional Specification", Version 2.0.0, Order No. AA-X435A-TK. [3] Digital Equipment Corporation, "DNA Maintenance Operations Functional Specification", Version 3.0.0, Order No. AA-X436A- TK. Security Considerations Security issues are not discussed in this memo. Chairman's Address This proposal is the product of the Point-to-Point Protocol Working Group of the Internet Engineering Task Force (IETF). The working group can be contacted via the chair: Stev Knowles FTP Software 26 Princess Street Wakefield, MA 01880-3004 Phone: (617) 246-0900 x270 EMail: Stev@FTP.com Author's Address Questions about this memo can also be directed to the author: Steven J. Senum Network Systems Corporation 7600 Boone Avenue North Minneapolis, MN 55428 Phone: (612) 424-4888 EMail: sjs@network.com Senum [Page 7] Internet Draft DECnet Point-to-Point May 31, 1991 Acknowledgments The author wishes to thank Jim Muchow (Network Systems Corporation), and Arthur Harvey (Digital Equipment Corporation) for their input to this memo. Senum [Page 8]