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'4' -- Possible downref: Non-RFC (?) normative reference: ref. '5' -- Possible downref: Non-RFC (?) normative reference: ref. '6' -- Possible downref: Non-RFC (?) normative reference: ref. '7' Summary: 11 errors (**), 0 flaws (~~), 2 warnings (==), 7 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group Andrew M. Fuqua 3 Internet Draft IBM 4 expires in six months March 1996 6 The PPP SNA Control Protocol (SNACP) 7 draft-ietf-pppext-snacp-01.txt 9 Status of this Memo 11 This document is a submission to the Point-to-Point Protocol Working 12 Group of the Internet Engineering Task Force (IETF). Comments should 13 be submitted to the ietf-ppp@merit.edu mailing list. 15 Distribution of this memo is unlimited. 17 Internet Drafts are working documents of the Internet Engineering 18 Task Force (IETF), its Areas, and its Working Groups. Note that 19 other groups may also distribute working documents as Internet 20 Drafts. 22 Internet Drafts are draft documents valid for a maximum of six 23 months. Internet Drafts may be updated, replaced, or obsoleted by 24 other documents at any time. It is not appropriate to use Internet 25 Drafts as reference material or to cite them other than as a 26 ``working draft'' or ``work in progress.'' 28 Please check the 1id-abstracts.txt listing contained in the 29 internet-drafts Shadow Directories on nic.ddn.mil, ds.internic.net, 30 venera.isi.edu, nic.nordu.net, or munnari.oz.au to learn the current 31 status of any Internet Draft. 33 Abstract 35 The Point-to-Point Protocol (PPP) [1] provides a standard method for 36 transporting multi-protocol datagrams over point-to-point links. PPP 37 defines an extensible Link Control Protocol, and proposes a family of 38 Network Control Protocols for establishing and configuring different 39 network-layer protocols. 41 This document defines the Network Control Protocols for establishing 42 and configuring Systems Network Architecture (SNA) over PPP and SNA 43 over LLC 802.2 over PPP. 45 1. Introduction 47 PPP has three main components: 49 1. A method for encapsulating multi-protocol datagrams. 51 2. A Link Control Protocol (LCP) for establishing, configuring, 52 and testing the data-link connection. 54 3. A family of Network Control Protocols for establishing and 55 configuring different network-layer protocols. 57 In order to establish communications over a point-to-point link, each 58 end of the PPP link must first send LCP packets to configure and test 59 the data link. After the link has been established and optional 60 facilities have been negotiated as needed by the LCP, PPP must send 61 SNACP packets to choose and configure the SNA network-layer protocol. 62 Once SNACP has reached the Opened state, SNA datagrams can be sent 63 over the link. 65 The link will remain configured for communications until explicit LCP 66 or SNACP packets close the link down, or until some external event 67 occurs (an inactivity timer expires or network administrator 68 intervention). 70 1.1. Specification of Requirements 72 In this document, several words are used to signify the requirements 73 of the specification. These words are often capitalized. 75 MUST This word, or the adjective "required", means that the 76 definition is an absolute requirement of the specification. 78 MUST NOT This phrase means that the definition is an absolute 79 prohibition of the specification. 81 SHOULD This word, or the adjective "recommended", means that there 82 may exist valid reasons in particular circumstances to 83 ignore this item, but the full implications must be 84 understood and carefully weighed before choosing a 85 different course. 87 MAY This word, or the adjective "optional", means that this 88 item is one of an allowed set of alternatives. An 89 implementation which does not include this option MUST be 90 prepared to interoperate with another implementation which 91 does include the option. 93 1.2. Terminology 95 This document frequently uses the following terms: 97 datagram The unit of transmission in the network layer (such as IP). 98 A datagram may be encapsulated in one or more packets 99 passed to the data link layer. 101 frame The unit of transmission at the data link layer. A frame 102 may include a header and/or a trailer, along with some 103 number of units of data. 105 packet The basic unit of encapsulation, which is passed across the 106 interface between the network layer and the data link 107 layer. A packet is usually mapped to a frame; the 108 exceptions are when data link layer fragmentation is being 109 performed, or when multiple packets are incorporated into a 110 single frame. 112 peer The other end of the point-to-point link. 114 silently discard 115 This means the implementation discards the packet without 116 further processing. The implementation SHOULD provide the 117 capability of logging the error, including the contents of 118 the silently discarded packet, and SHOULD record the event 119 in a statistics counter. 121 PIU Path information unit. A message unit consisting of a 122 transmission header (TH) alone, or a TH followed by a basic 123 information unit (BIU) or a BIU segment. PIU is analogous 124 to datagram. 126 TH Transmission header. Control information, optionally 127 followed by a basic information unit (BIU) or a BIU 128 segment, that is created and used by path control to route 129 message units and to control their flow within the network. 131 BIU Basic information unit. In SNA, the unit of data and 132 control information passed between half-sessions. It 133 consists of a request/response header (RH) followed by a 134 request/response unit (RU). 136 message unit 137 In SNA, the unit of data processed by any layer; for 138 example, a basic information unit (BIU), a path information 139 unit (PIU), or a request/response unit (RU). 141 NLP Network Layer Packet. In High Performance Routing (HPR), 142 the message unit used to carry data over the route. 143 Network Layer Packet is analogous to datagram. 145 2. A PPP Network Control Protocol for SNA 147 The SNA Control Protocol (SNACP) is responsible for configuring, 148 enabling, and disabling SNA on both ends of the point-to-point link. 149 SNACP uses the same packet exchange mechanism as the Link Control 150 Protocol (LCP). SNACP packets may not be exchanged until PPP has 151 reached the Network-Layer Protocol phase. SNACP packets received 152 before this phase is reached should be silently discarded. 154 Note that there are actually two SNA Network Control Protocols; one 155 for SNA over LLC 802.2 and another for SNA without LLC 802.2. These 156 SNA NCPs are negotiated separately and independently of each other. 158 The SNA Control Protocol is exactly the same as the Link Control 159 Protocol [1] with the following exceptions: 161 Frame Modifications 163 The packet may utilize any modifications to the basic frame format 164 which have been negotiated during the Link Establishment phase. 166 Data Link Layer Protocol Field 168 Exactly one SNACP packet is encapsulated in the PPP Information 169 field, where the PPP Protocol field indicates type hex 804B (SNA 170 over LLC 802.2) or hex 804D (SNA). 172 Code field 174 Only Codes 1 through 7 (Configure-Request, Configure-Ack, 175 Configure-Nak, Configure-Reject, Terminate-Request, Terminate-Ack 176 and Code-Reject) are used. Other Codes should be treated as 177 unrecognized and should result in Code-Rejects. 179 Timeouts 181 SNACP packets may not be exchanged until PPP has reached the 182 Network-Layer Protocol phase. An implementation should be prepared 183 to wait for Authentication and Link Quality Determination to 184 finish before timing out waiting for a Configure-Ack or other 185 response. It is suggested that an implementation give up only 186 after user intervention or a configurable amount of time. 188 Configuration Option Types 190 There are no Configuration Options for SNA or for SNA over LLC 191 802.2. 193 3. Sending SNA PIUs and NLPs. 195 Before any SNA packets may be communicated, PPP must reach the 196 Network-Layer Protocol phase, and the appropriate SNA Control 197 Protocol must reach the Opened state. 199 The maximum length of a SNA packet transmitted over a PPP link is the 200 same as the maximum length of the Information field of a PPP 201 encapsulated packet. 203 The format of the PPP Information field itself is the same as that 204 defined in [1]. Detailed information on SNA and APPN can be found in 205 [3], [4], [5], [6], and [7]. 207 3.1. Sending SNA XID or FID2 PIUs over LLC 209 Exactly one SNA XID or FID2 PIU over LLC 802.2 is encapsulated in the 210 PPP Information field, where the PPP Protocol field indicates type 211 hex 004B (SNA over LLC 802.2). 213 A summary of this frame structure, beginning with the PPP Protocol 214 field, is shown below. The fields are transmitted from left to right. 216 -- LLC portion (PPP Information Field) ------------- 217 | | 218 -+----------+----------+----------+----------+-------------------+- 219 | Protocol | DSAP | SSAP | Control | LLC Information | 220 | 0x004B | Address | Address | Field | Field | 221 -+----------+----------+----------+----------+-------------------+- 223 The LLC information field contains the XID or FID2 PIU. LLC(2) is 224 included in this format for link-level error recovery. Error 225 recovery is done by the routers at each end of the PPP link. 227 3.2. Sending HPR Network Layer Packets (NLPs) 229 Exactly one HPR Network Layer Packet (NLP) is encapsulated in the PPP 230 Information field, where the PPP Protocol field indicates type hex 231 004D (SNA). 233 A summary of this frame structure, beginning with the PPP Protocol 234 field, is shown below. The fields are transmitted from left to right. 236 -- HPR Network Layer Packet (NLP) -- 237 | (PPP Information Field) | 238 -+----------+--------+--------+------------------+- 239 | Protocol | NHDR | THDR | data | 240 | 0x004D | | | | 241 -+----------+--------+--------+------------------+- 243 3.3. Other Considerations 245 It is architecturally possible to transport HPR NLPs over LLC over 246 PPP using PPP Protocol field type hex 004B (SNA over LLC 802.2) if 247 the optional HPR link-level error recover tower is included in the 248 implementation. 250 Security Considerations 252 Security issues are not discussed in this memo. 254 References 256 [1] Simpson, W. A., "The Point-to-Point Protocol (PPP)", STD 51, 257 RFC 1661, Daydreamer, July 1994. 259 [2] Reynolds, J., and Postel, J., "Assigned Numbers", STD 2, RFC 260 1700, USC/Information Sciences Institute, October 1994. 262 [3] "SNA Formats", GA27-3136, IBM. 264 [4] "SNA APPN Architecture Reference", SC30-3422, IBM. 266 [5] "APPN Architecture and Product Implementations Tutorial", 267 GG24-3669-02, IBM. 269 [6] APPN Implementers Workshop homepage, 270 http://www.raleigh.ibm.com/app/aiwhome.htm 272 [7] "APPN High Performance Routing (HPR) Architecture", 273 ftp://networking.raleigh.ibm.com/pub/standards/aiw/appn/hpr 275 IBM documents are orderable through 1-800-879-2755. 277 Acknowledgements 279 Some of the text in this document is taken from previous documents 280 produced by the Point-to-Point Protocol Working Group of the Internet 281 Engineering Task Force (IETF). 283 Some of the text in this document is taken from miscellaneous IBM 284 documents. 286 Many people provided suggestions and portions of text for this 287 document. Special thanks to Allen Carriker, Marcia Peters, and Scott 288 G. Wasson. 290 Chair's Address 292 The working group can be contacted via the current chair: 294 Fred Baker 295 Cisco Systems 296 519 Lado Drive 297 Santa Barbara, California, 93111 299 EMail: fred@cisco.com 301 Author's Address 303 Questions about this memo can also be directed to: 305 Andrew M. Fuqua 306 International Business Machines Corporation 307 P. O. Box 12195 308 Research Triangle Park, NC 27709 310 EMail: fuqua@vnet.ibm.com 311 Table of Contents 313 1. Introduction .......................................... 1 314 1.1 Specification of Requirements ................... 1 315 1.2 Terminology ..................................... 2 317 2. A PPP Network Control Protocol for SNA ................ 4 319 3. Sending SNA PIUs and NLPs. ............................ 5 320 3.1 Sending SNA XID or FID2 PIUs over LLC ........... 5 321 3.2 Sending HPR Network Layer Packets (NLPs) ........ 5 322 3.3 Other Considerations ............................ 6 324 SECURITY CONSIDERATIONS ...................................... 7 326 REFERENCES ................................................... 7 328 ACKNOWLEDGEMENTS .......................................... 7 330 CHAIR'S ADDRESS .............................................. 7 332 AUTHOR'S ADDRESS ............................................. 8