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No rights are granted, in any manner or form, to use Whistle 11.\" Communications, Inc. trademarks, including the mark "WHISTLE 12.\" COMMUNICATIONS" on advertising, endorsements, or otherwise except as 13.\" such appears in the above copyright notice or in the software. 14.\" 15.\" THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND 16.\" TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO 17.\" REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE, 18.\" INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF 19.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. 20.\" WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY 21.\" REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS 22.\" SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE. 23.\" IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES 24.\" RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING 25.\" WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, 26.\" PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR 27.\" SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY 28.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30.\" THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY 31.\" OF SUCH DAMAGE. 32.\" 33.\" Author: Archie Cobbs <archie@FreeBSD.org> 34.\" 35.\" $FreeBSD$ 36.\" $Whistle: ng_ppp.8,v 1.3 1999/01/25 23:46:27 archie Exp $ 37.\" 38.Dd January 19, 1999 39.Dt NG_PPP 4 40.Os 41.Sh NAME 42.Nm ng_ppp 43.Nd PPP protocol netgraph node type 44.Sh SYNOPSIS 45.In netgraph/ng_ppp.h 46.Sh DESCRIPTION 47The 48.Nm ppp 49node type performs multiplexing for the PPP protocol. 50It handles only packets that contain data, and forwards protocol negotiation 51and control packets to a separate controlling entity (e.g., a 52user-land daemon). 53This approach combines the fast dispatch of 54kernel implementations with the configuration flexibility of a 55user-land implementations. 56The PPP node type directly supports 57multi-link PPP, Van Jacobson compression, PPP compression, PPP 58encryption, and the IP, IPX, and AppleTalk protocols. 59A single PPP node corresponds to one PPP multi-link bundle. 60.Pp 61There is a separate hook for each PPP link in the bundle, plus 62several hooks corresponding to the directly supported protocols. 63For compression and encryption, separate attached nodes are required 64to do the actual work. 65The node type used will of course depend on the algorithm negotiated. 66There is also a 67.Dv bypass 68hook which is used to handle any protocol not directly supported 69by the node. 70This includes all of the control protocols: LCP, IPCP, 71CCP, etc. 72Typically this node is connected to a user-land daemon via a 73.Xr ng_socket 4 74type node. 75.Sh ENABLING FUNCTIONALITY 76In general, the PPP node enables a specific link or functionality when 77(a) a 78.Dv NGM_PPP_SET_CONFIG 79message has been received which enables it, and 80(b) the corresponding hook(s) are connected. 81This allows the controlling entity to use either method (a) or (b) 82(or both) to control the node's behavior. 83When a link is connected but disabled, traffic can still flow on 84the link via the 85.Dv bypass 86hook (see below). 87.Sh LINK HOOKS 88During normal operation, the individual PPP links are connected to hooks 89.Dv link0 , 90.Dv link1 , 91etc. Up to 92.Dv NG_PPP_MAX_LINKS 93links are supported. 94These device-independent hooks transmit and receive full PPP 95frames, which include the PPP protocol, address, control, and 96information fields, but no checksum or other link-specific fields. 97.Pp 98On outgoing frames, when protocol compression 99has been enabled and the protocol number is suitable for compression, 100the protocol field will be compressed (i.e., sent as one byte 101instead of two). 102Either compressed or uncompressed protocol fields 103are accepted on incoming frames. 104Similarly, if address and control 105field compression has been enabled for the link, the address and 106control fields will be omitted (except for LCP frames as required 107by the standards). 108Incoming frames have the address and control fields 109stripped automatically if present. 110.Pp 111Since all negotiation is handled outside the PPP node, the links 112should not be connected and enabled until the corresponding link 113has reached the network phase (i.e., LCP negotiation and authentication 114have completed successfully) and the PPP node has been informed of 115the link parameters via the 116.Dv NGM_PPP_LINK_CONFIG 117message. 118.Pp 119When a link is connected but disabled, all received frames are forwarded 120directly out the 121.Dv bypass 122hook, and conversely, frames may be transmitted via the 123.Dv bypass 124hook as well. 125This mode is appropriate for the link authentication phase. 126As soon as the link is enabled, the PPP node will 127begin processing frames received on the link. 128.Sh COMPRESSION AND ENCRYPTION 129Compression is supported via two hooks, 130.Dv compress 131and 132.Dv decompress . 133When enabled and connected, the PPP node writes outgoing frames on the 134.Dv comp 135hook and expects to receive back the compressed frame on the same hook. 136Similarly, the 137.Dv decompress 138hook is used to uncompress incoming frames when decompression is 139negotiated (compression and decompression are independently negotiable). 140The type of node attached to these hooks should correspond 141to the type of compression negotiated, e.g., Deflate, Predictor-1, etc. 142.Pp 143Encryption works exactly analogously via the 144.Dv encrypt 145and 146.Dv decrypt 147nodes. 148Data is always compressed before being encrypted, 149and decrypted before being decompressed. 150.Pp 151Only bundle-level compression and encryption is directly supported; 152link-level compression and encryption can be handled transparently 153by downstream nodes. 154.Sh VAN JACOBSON COMPRESSION 155When all of the 156.Dv vjc_ip , 157.Dv vjc_vjcomp , 158.Dv vjc_vjuncomp , 159and 160.Dv vjc_vjip 161hooks are connected, and the corresponding configuration flag is 162enabled, Van Jacobson compression and/or decompression will become active. 163Normally these hooks connect to the corresponding hooks of a single 164.Xr ng_vjc 4 165node. The PPP node is compatible with the 166.Dq pass through 167modes of the 168.Xr ng_vjc 4 169node type. 170.Sh BYPASS HOOK 171When a frame is received on a link with an unsupported protocol, 172or a protocol which is disabled or for which the corresponding hook 173is unconnected, the PPP node forwards the frame out the 174.Dv bypass 175hook, prepended with a four byte prefix. 176This first two bytes of 177the prefix indicate the link number on which the frame was received 178(in network order). 179For such frames received over the bundle (i.e., encapsulated in the 180multi-link protocol), the special link number 181.Dv NG_PPP_BUNDLE_LINKNUM 182is used. After the two byte link number is the two byte PPP protocol number 183(also in network order). 184The PPP protocol number is two bytes long even if the original frame 185was protocol compressed. 186.Pp 187Conversely, any data written to the 188.Dv bypass 189hook is assumed to be in this same format. 190The four byte header is 191stripped off, the PPP protocol number is prepended (possibly compressed), 192and the frame is delivered over the desired link. 193If the link number is 194.Dv NG_PPP_BUNDLE_LINKNUM 195the frame will be delivered over the multi-link bundle; or, if multi-link 196is disabled, over the (single) PPP link. 197.Pp 198Typically when the controlling entity receives an unexpected packet on the 199.Dv bypass 200hook it responds either by dropping the frame (if it's not ready for 201the protocol) or with an LCP protocol reject (if it doesn't recognize 202or expect the protocol). 203.Sh MULTILINK OPERATION 204To enable multi-link PPP, the corresponding configuration flag must be set 205and at least one link connected. 206The PPP node will not allow more than 207one link to be connected if multi-link is not enabled, nor will it allow 208certain multi-link settings to be changed while multi-link operation is 209active (e.g., short sequence number header format). 210.Pp 211Since packets are sent as fragments across multiple individual links, 212it is important that when a link goes down the PPP node is notified 213immediately, either by disconnecting the corresponding hook or disabling 214the link via the 215.Dv NGM_PPP_SET_CONFIG 216control message. 217.Pp 218Each link has configuration parameters for latency (specified in 219milliseconds) and bandwidth (specified in tens of bytes per second). 220The PPP node can be configured for 221.Em round-robin 222or 223.Em optimized 224packet delivery. 225.Pp 226When configured for round-robin delivery, the latency and bandwidth 227values are ignored and the PPP node simply sends each frame as a 228single fragment, alternating frames across all the links in the 229bundle. 230This scheme has the advantage that even if one link fails 231silently, some packets will still get through. 232It has the disadvantage 233of sub-optimal overall bundle latency, which is important for 234interactive response time, and sub-optimal overall bundle bandwidth 235when links with different bandwidths exist in the same bundle. 236.Pp 237When configured for optimal delivery, the PPP node distributes the 238packet across the links in a way that minimizes the time it takes 239for the completed packet to be received by the far end. 240This involves taking into account each link's latency, bandwidth, and 241current queue length. 242Therefore these numbers should be configured as accurately as possible. 243The algorithm does require 244some computation, so may not be appropriate for very slow machines 245and/or very fast links. 246.Pp 247As a special case, if all links have identical latency and bandwidth, 248then the above algorithm is disabled (because it is unnecessary) 249and the PPP node simply fragments frames into equal sized portions 250across all of the links. 251.Sh HOOKS 252This node type supports the following hooks: 253.Pp 254.Bl -tag -compact -width vjc_vjuncomp 255.It Dv link<N> 256Individual PPP link number 257.Dv <N> 258.It Dv compress 259Connection to compression engine 260.It Dv decompress 261Connection to decompression engine 262.It Dv encrypt 263Connection to encryption engine 264.It Dv decrypt 265Connection to decryption engine 266.It Dv vjc_ip 267Connection to 268.Xr ng_vjc 4 269.Dv ip 270hook 271.It Dv vjc_vjcomp 272Connection to 273.Xr ng_vjc 4 274.Dv vjcomp 275hook 276.It Dv vjc_vjuncomp 277Connection to 278.Xr ng_vjc 4 279.Dv vjuncomp 280hook 281.It Dv vjc_vjip 282Connection to 283.Xr ng_vjc 4 284.Dv vjip 285hook 286.It Dv inet 287IP packet data 288.It Dv atalk 289AppleTalk packet data 290.It Dv ipx 291IPX packet data 292.It Dv bypass 293Bypass hook; frames have a four byte header consisting of 294a link number and a PPP protocol number. 295.El 296.Sh CONTROL MESSAGES 297This node type supports the generic control messages, plus the following: 298.Bl -tag -width foo 299.It Dv NGM_PPP_SET_CONFIG 300This command configures all aspects of the node. 301This includes enabling 302multi-link PPP, encryption, compression, Van Jacobson compression, and IP, 303AppleTalk, and IPX packet delivery. 304It includes per-link configuration, 305including enabling the link, setting latency and bandwidth parameters, 306and enabling protocol field compression. 307Note that no link or functionality 308is active until the corresponding hook is also connected. 309This command takes a 310.Dv "struct ng_ppp_node_config" 311as an argument: 312.Bd -literal -offset 0n 313/* Per-link config structure */ 314struct ng_ppp_link_config { 315 u_char enableLink; /* enable this link */ 316 u_char enableProtoComp;/* enable protocol field compression */ 317 u_char enableACFComp; /* enable addr/ctrl field compression */ 318 u_int16_t mru; /* peer MRU */ 319 u_int32_t latency; /* link latency (in milliseconds) */ 320 u_int32_t bandwidth; /* link bandwidth (in bytes/second) */ 321}; 322 323/* Node config structure */ 324struct ng_ppp_node_config { 325 u_int16_t mrru; /* multilink peer MRRU */ 326 u_char enableMultilink; /* enable multilink */ 327 u_char recvShortSeq; /* recv multilink short seq # */ 328 u_char xmitShortSeq; /* xmit multilink short seq # */ 329 u_char enableRoundRobin; /* xmit whole packets */ 330 u_char enableIP; /* enable IP data flow */ 331 u_char enableAtalk; /* enable AppleTalk data flow */ 332 u_char enableIPX; /* enable IPX data flow */ 333 u_char enableCompression; /* enable PPP compression */ 334 u_char enableDecompression; /* enable PPP decompression */ 335 u_char enableEncryption; /* enable PPP encryption */ 336 u_char enableDecryption; /* enable PPP decryption */ 337 u_char enableVJCompression; /* enable VJ compression */ 338 u_char enableVJDecompression; /* enable VJ decompression */ 339 struct ng_ppp_link_config /* per link config params */ 340 links[NG_PPP_MAX_LINKS]; 341}; 342.Ed 343.Pp 344.It Dv NGM_PPP_GET_CONFIG 345Returns the current configuration as a 346.Dv "struct ng_ppp_node_config" . 347.It Dv NGM_PPP_GET_LINK_STATS 348This command takes a two byte link number as an argument and returns a 349.Dv "struct ng_ppp_link_stat" 350containing statistics for the corresponding link. Here 351.Dv NG_PPP_BUNDLE_LINKNUM 352is a valid link number corresponding to the multi-link bundle. 353.It Dv NGM_PPP_CLR_LINK_STATS 354This command takes a two byte link number as an argument and 355clears the statistics for that link. 356.It Dv NGM_PPP_GETCLR_LINK_STATS 357Same as 358.Dv NGM_PPP_GET_LINK_STATS , 359but also atomically clears the statistics as well. 360.El 361.Pp 362This node type also accepts the control messages accepted by the 363.Xr ng_vjc 4 364node type. When received, these messages are simply forwarded to 365the adjacent 366.Xr ng_vjc 4 367node, if any. This is particularly useful when the individual 368PPP links are able to generate 369.Dv NGM_VJC_RECV_ERROR 370messages (see 371.Xr ng_vjc 4 372for a description). 373.Sh SHUTDOWN 374This node shuts down upon receipt of a 375.Dv NGM_SHUTDOWN 376control message, or when all hooks have been disconnected. 377.Sh SEE ALSO 378.Xr netgraph 4 , 379.Xr ng_async 4 , 380.Xr ng_iface 4 , 381.Xr ng_mppc 4 , 382.Xr ng_pppoe 4 , 383.Xr ng_vjc 4 , 384.Xr ngctl 8 385.Rs 386.%A W. Simpson 387.%T "The Point-to-Point Protocol (PPP)" 388.%O RFC 1661 389.Re 390.Rs 391.%A K. Sklower 392.%A B. Lloyd 393.%A G. McGregor 394.%A D. Carr 395.%A T. Coradetti 396.%T "The PPP Multilink Protocol (MP)" 397.%O RFC 1990 398.Re 399.Sh HISTORY 400The 401.Nm 402node type was implemented in 403.Fx 4.0 . 404.Sh AUTHORS 405.An Archie Cobbs Aq archie@FreeBSD.org 406