RFC3485
Network Working Group M. Garcia-Martin Request for Comments: 3485 Ericsson Category: Standards Track C. Bormann
J. Ott
TZI/Uni Bremen
R. Price
Siemens/Roke Manor
A. B. Roach
dynamicsoft
February 2003
The Session Initiation Protocol (SIP) and Session Description Protocol (SDP) Static Dictionary for Signaling Compression (SigComp)
Status of this Memo
This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract
The Session Initiation Protocol (SIP) is a text-based protocol for initiating and managing communication sessions. The protocol can be compressed by using Signaling Compression (SigComp). Similarly, the Session Description Protocol (SDP) is a text-based protocol intended for describing multimedia sessions for the purposes of session announcement, session invitation, and other forms of multimedia session initiation. This memo defines the SIP/SDP-specific static dictionary that SigComp may use in order to achieve higher efficiency. The dictionary is compression algorithm independent.
Contents
Introduction
SIP [3] and SDP [24] are text-based protocols that use the UTF-8 charset (RFC 2279 [5]). SIP and SDP were designed for rich bandwidth links. However, when SIP/SDP is run over narrow bandwidth links, such as radio interfaces or low speed serial links, the session setup time increases substantially, compared to an operation over a rich bandwidth link.
The session setup time can decrease dramatically if the SIP/SDP signaling is compressed. The signaling compression mechanisms specified in SigComp [1] provide a multiple compression/decompression algorithm framework to compress and decompress text-based protocols such as SIP and SDP.
When compression is used in SIP/SDP, the compression achieves its maximum rate once a few message exchanges have taken place. This is due to the fact that the first message the compressor sends to the decompressor is only partially compressed, as there is not a previous stored state to compress against. As the goal is to reduce the session setup time as much as possible, it seems sensible to investigate a mechanism to boost the compression rate from the first message.
In this memo we introduce the static dictionary for SIP and SDP. The dictionary is to be used in conjunction with SIP, SDP and SigComp. The static SIP/SDP dictionary constitutes a SigComp state that can be referenced in the first SIP message that the compressor sends out.
Design considerations
The static SIP/SDP dictionary is a collection of well-known strings that appear in most of the SIP and SDP messages. The dictionary is not a comprehensive list of reserved words, but it includes many of the strings that appear in SIP and SDP signaling.
The static dictionary is unique and MUST be available in all SigComp implementations for SIP/SDP. The dictionary is not intended to evolve as SIP or SDP evolve. It is defined once, and stays as is forever. This solves the problems of updating, upgrading and finding out the dictionary that is supported at the remote end when several versions of the same dictionary coexist.
Appendix A contains the collection of strings that SIP contributed to the static dictionary. The appendix includes references to the documents that define those strings.
Appendix B contains the collection of strings that SDP contributed to the static dictionary. Again, the appendix includes references to the documents that define those strings.
While these appendices are of an informative nature, Section 3 gives the normative binary form of the SIP/SDP dictionary. This is the dictionary that is included in the SigComp implementation. This dictionary has been formed from the collection of individual dictionaries given in appendices A and B.
The two input collections are collections of UTF-8 encoded character strings. In order to facilitate the readability, the appendices describe them in one table for each collection. In these tables, each row represents an entry. Each entry contains the string that actually occurs in the dictionary, its priority (see below), its offset from the first octet and its length (both in hexadecimal), and one or more references that elucidate why this string is expected to occur in SIP/SDP messages. Note: Length in this document always refers to octets.
The columns in the tables are described as follows:
String: represents the UTF-8 string that is inserted into the dictionary. Note that the quotes (") are not part of the string itself. Note also that the notation [CRLF] represents a Carriage Return character (ASCII code 0x0D) followed by a Line Feed character (ASCII code 0x0A).
Pr: indicates the priority of this string within the dictionary. Some compression algorithms, such as DEFLATE, offer an increased efficiency when the most commonly used strings are located at the bottom of the dictionary. To facilitate generating a dictionary that has the most frequently occurring strings further down at the bottom, we have decided to allocate a priority to each string in the dictionary. Priorities range from 1 until 5. A low number in the priority column (e.g., 1) indicates that we believe in a high probability of finding the string in SIP or SDP messages. A high number in the priority column (e.g., 5) indicates lower probability of finding the string in a SIP or SDP message. This is typically the case for less frequent error codes or optional infrequent tags.
Off: indicates the hexadecimal offset of the entry with respect to the first octet in the dictionary. Note that several strings in the collections can share space in the dictionary if they exhibit suitable common substrings.
Len: the length of the string (in octets, in hexadecimal).
References: contains one or more references to the specification and the section within the specification where the string is defined.
Note that the strings stored in the dictionary are case sensitive. (Again, the strings do not comprise the quotes ("), they are just shown here to increase the readability.) Where the string is a header field, we also included the colon ":" and the amount of white space expected to occur. Note that this means that not all messages that conform to the SIP Augmented BNF, which allows other combinations (e.g., a white space or horizontal tabulator before the colon (":") sign), will benefit as much from the dictionary -- the best increase in compression performance is to be expected for messages that use the recommended formatting guidelines for SIP.
Some strings appear followed by an equal sign and some others do not. This depends on whether the string is part of a parameter name or a parameter value.
In a SIP message, all the SIP headers terminate with a CRLF pair of characters. As these characters are appended to the end of each SIP header line, right after the header values, and because the header values are typically not part of the static SIP dictionary, we cannot include the terminating CRLF as part of the SIP static dictionary. Instead, the approach we have taken is to include in each header field entry the CRLF from the previous line that prefixes every header field. We have represented CRLF by the notation [CRLF]. Therefore, in generating the actual binary dictionary, an entry in the dictionary represented as: "[CRLF]From: " has been interpreted as
an entry whose value is CR, LF, the word From, a colon and a whitespace.
Note that most SIP header field names are included with the full string from CRLF to the colon-blank pair. However, in certain situations, when the likelihood of occurrence is not considered high (as indicated by a priority value of 3 to 5), and when there are common substrings shared by a number of headers, we have added one entry with the common substring and several entries with the non- common substrings remaining. An example is the "Proxy-Authenticate" and "Proxy-Authorization" headers. There are three entries in the dictionary: the common substring "[CRLF]Proxy-", and the non-common substrings "Authenticate: " and "Authorization: ". This allows the re-use of the non-common substrings by other entries and may save a number of bytes in the binary form of the dictionary. Note that this splitting mechanism does not apply with strings that are likely to occur very often (those whose priority is set to 1 or 2).
SIP responses start with a status code (e.g., "302") and a reason phrase (e.g., "Moved Temporarily"). The status code is a normative part, whereas the reason phrase is not normative, it is just a suggested text. For instance, both "302 Moved Temporarily" and "302 Redirect" are valid beginnings of SIP responses.
In the SIP dictionary we have included two entries per response code, one including only the status code and a space (e.g., "302 ") and another one including both the status code and the suggested reason phrase (e.g., "302 Moved Temporarily"). The former can be used when the SIP response changed the suggested reason phrase to another one. The latter can be used when the suggested reason phrase is part of the response. In this way, we accommodate both alternatives. (Note that in the actual dictionary, both strings occupy the same space in the string subset, but have two separate entries in the table subset.)
Binary representation of the SIP/SDP dictionary
This section contains the result of combining the SIP and the SDP dictionaries described in appendices A and B in order to create a single dictionary that is loaded into SigComp as a state.
The binary SigComp dictionary is comprised of two parts, the concatenation of which serves as the state value of the state item: A string subset, which contains all strings in the contributing collections as a substring (roughly ordered such that strings with low priority numbers occur at the end), and a table subset, which contains pairs of length and offset values for all the strings in the contributing collections. In each of these pairs, the length is
stored as a one-byte value, and the offset is stored as a two-byte value that has had 1024 added to the offset (this allows direct referencing from the stored value if the dictionary state has been loaded at address 1024).
The intention is that all compression algorithms will be able to use the (or part of the) string subset, and some compression methods, notably those that are related to the LZ78 family, will also use the table in order to form an initial set of tokens for that compression method. The text below therefore gives examples for referencing both the table subset and the string subset of the dictionary state item.
As defined in section 3.3.3 in the Signaling Compression specification [1], a SigComp state is characterized by a certain set of information. For the static SIP/SDP dictionary, the information in the following Table 1 fully characterizes the state item.
Note that the string subset of the dictionary can be accessed using:
STATE-ACCESS (%ps, 6, 0, 0x0D8C, %sa, 0),
and the table subset can be accessed using:
STATE-ACCESS (%ps, 6, 0x0D8C, 0x0558, %sa, 0),
where %ps points to UDVM memory containing
0xfbe507dfe5e6
and %sa is the desired destination address in UDVM memory (with UDVM byte copying rules applied).
If only a subset of the dictionary up to a specific priority is desired (e.g., to save UDVM space), the values for the third and forth operand in these STATE-ACCESS instructions can be changed to:
Priorities String String Table Table desired offset length offset length
==== ====== ====== ======
1 only 0x0CB2 0x00DA 0x0D8C 0x003F 1..2 0x0920 0x046C 0x0D8C 0x0147 1..3 0x07B8 0x05D4 0x0D8C 0x01A7 1..4 0x0085 0x0D07 0x0D8C 0x044A 1..5 0x0000 0x0D8C 0x0D8C 0x0558
The state item consists of the following elements:
Name: Value:
=============== ==================
state_identifier 0xfbe507dfe5e6aa5af2abb914ceaa05f99ce61ba5 state_length 0x12E4 state_address 0 (not relevant for the dictionary) state_instruction 0 (not relevant for the dictionary) minimum_access_length 6 state_value Representation of the table below.
0000 0d0a 5265 6a65 6374 2d43 6f6e 7461 6374 ..Reject-Contact 0010 3a20 0d0a 4572 726f 722d 496e 666f 3a20 : ..Error-Info: 0020 0d0a 5469 6d65 7374 616d 703a 200d 0a43 ..Timestamp: ..C 0030 616c 6c2d 496e 666f 3a20 0d0a 5265 706c all-Info: ..Repl 0040 792d 546f 3a20 0d0a 5761 726e 696e 673a y-To: ..Warning: 0050 200d 0a53 7562 6a65 6374 3a20 3b68 616e ..Subject: ;han 0060 646c 696e 673d 696d 6167 653b 7075 7270 dling=image;purp 0070 6f73 653d 3b63 6175 7365 3d3b 7465 7874 ose=;cause=;text 0080 3d63 6172 6433 3030 204d 756c 7469 706c =card300 Multipl 0090 6520 4368 6f69 6365 736d 696d 6573 7361 e Choicesmimessa 00A0 6765 2f73 6970 6672 6167 3430 3720 5072 ge/sipfrag407 Pr 00B0 6f78 7920 4175 7468 656e 7469 6361 7469 oxy Authenticati 00C0 6f6e 2052 6571 7569 7265 6469 6765 7374 on Requiredigest 00D0 2d69 6e74 6567 7269 7479 3438 3420 4164 -integrity484 Ad 00E0 6472 6573 7320 496e 636f 6d70 6c65 7465 dress Incomplete 00F0 6c65 7068 6f6e 652d 6576 656e 7473 3439 lephone-events49 0100 3420 5365 6375 7269 7479 2041 6772 6565 4 Security Agree 0110 6d65 6e74 2052 6571 7569 7265 6465 6163 ment Requiredeac 0120 7469 7661 7465 6434 3831 2043 616c 6c2f tivated481 Call/ 0130 5472 616e 7361 6374 696f 6e20 446f 6573 Transaction Does 0140 204e 6f74 2045 7869 7374 616c 653d 3530 Not Existale=50 0150 3020 5365 7276 6572 2049 6e74 6572 6e61 0 Server Interna 0160 6c20 4572 726f 726f 6275 7374 2d73 6f72 l Errorobust-sor 0170 7469 6e67 3d34 3136 2055 6e73 7570 706f ting=416 Unsuppo 0180 7274 6564 2055 5249 2053 6368 656d 6572 rted URI Schemer 0190 6765 6e63 7934 3135 2055 6e73 7570 706f gency415 Unsuppo 01A0 7274 6564 204d 6564 6961 2054 7970 656e rted Media Typen 01B0 6469 6e67 3438 3820 4e6f 7420 4163 6365 ding488 Not Acce 01C0 7074 6162 6c65 2048 6572 656a 6563 7465 ptable Herejecte 01D0 6434 3233 2049 6e74 6572 7661 6c20 546f d423 Interval To 01E0 6f20 4272 6965 6672 6f6d 2d74 6167 512e o Briefrom-tagQ. 01F0 3835 3035 2056 6572 7369 6f6e 204e 6f74 8505 Version Not 0200 2053 7570 706f 7274 6564 3430 3320 466f Supported403 Fo 0210 7262 6964 6465 6e6f 6e2d 7572 6765 6e74 rbiddenon-urgent 0220 3432 3920 5072 6f76 6964 6520 5265 6665 429 Provide Refe 0230 7272 6f72 2049 6465 6e74 6974 7934 3230 rror Identity420 0240 2042 6164 2045 7874 656e 7369 6f6e 6f72 Bad Extensionor
0250 6573 6f75 7263 650d 0a61 3d6b 6579 2d6d esource..a=key-m 0260 676d 743a 6d69 6b65 794f 5054 494f 4e53 gmt:mikeyOPTIONS 0270 204c 616e 6775 6167 653a 2035 3034 2053 Language: 504 S 0280 6572 7665 7220 5469 6d65 2d6f 7574 6f2d erver Time-outo- 0290 7461 670d 0a41 7574 6865 6e74 6963 6174 tag..Authenticat 02A0 696f 6e2d 496e 666f 3a20 4465 6320 3338 ion-Info: Dec 38 02B0 3020 416c 7465 726e 6174 6976 6520 5365 0 Alternative Se 02C0 7276 6963 6535 3033 2053 6572 7669 6365 rvice503 Service 02D0 2055 6e61 7661 696c 6162 6c65 3432 3120 Unavailable421 02E0 4578 7465 6e73 696f 6e20 5265 7175 6972 Extension Requir 02F0 6564 3430 3520 4d65 7468 6f64 204e 6f74 ed405 Method Not 0300 2041 6c6c 6f77 6564 3438 3720 5265 7175 Allowed487 Requ 0310 6573 7420 5465 726d 696e 6174 6564 6175 est Terminatedau 0320 7468 2d69 6e74 6572 6c65 6176 696e 673d th-interleaving= 0330 0d0a 6d3d 6170 706c 6963 6174 696f 6e20 ..m=application 0340 4175 6720 3531 3320 4d65 7373 6167 6520 Aug 513 Message 0350 546f 6f20 4c61 7267 6536 3837 2044 6961 Too Large687 Dia 0360 6c6f 6720 5465 726d 696e 6174 6564 3330 log Terminated30 0370 3220 4d6f 7665 6420 5465 6d70 6f72 6172 2 Moved Temporar 0380 696c 7933 3031 204d 6f76 6564 2050 6572 ily301 Moved Per 0390 6d61 6e65 6e74 6c79 6d75 6c74 6970 6172 manentlymultipar 03A0 742f 7369 676e 6564 0d0a 5265 7472 792d t/signed..Retry- 03B0 4166 7465 723a 2047 4d54 6875 2c20 3430 After: GMThu, 40 03C0 3220 5061 796d 656e 7420 5265 7175 6972 2 Payment Requir 03D0 6564 0d0a 613d 6f72 6965 6e74 3a6c 616e ed..a=orient:lan 03E0 6473 6361 7065 3430 3020 4261 6420 5265 dscape400 Bad Re 03F0 7175 6573 7472 7565 3439 3120 5265 7175 questrue491 Requ 0400 6573 7420 5065 6e64 696e 6735 3031 204e est Pending501 N 0410 6f74 2049 6d70 6c65 6d65 6e74 6564 3430 ot Implemented40 0420 3620 4e6f 7420 4163 6365 7074 6162 6c65 6 Not Acceptable 0430 3630 3620 4e6f 7420 4163 6365 7074 6162 606 Not Acceptab 0440 6c65 0d0a 613d 7479 7065 3a62 726f 6164 le..a=type:broad 0450 6361 7374 6f6e 6534 3933 2055 6e64 6563 castone493 Undec 0460 6970 6865 7261 626c 650d 0a4d 494d 452d ipherable..MIME- 0470 5665 7273 696f 6e3a 204d 6179 2034 3832 Version: May 482 0480 204c 6f6f 7020 4465 7465 6374 6564 0d0a Loop Detected.. 0490 4f72 6761 6e69 7a61 7469 6f6e 3a20 4a75 Organization: Ju 04A0 6e20 6d6f 6465 2d63 6861 6e67 652d 6e65 n mode-change-ne 04B0 6967 6862 6f72 3d63 7269 7469 6361 6c65 ighbor=criticale 04C0 7274 6370 2d66 6234 3839 2042 6164 2045 rtcp-fb489 Bad E 04D0 7665 6e74 6c73 0d0a 556e 7375 7070 6f72 ventls..Unsuppor 04E0 7465 643a 204a 616e 2035 3032 2042 6164 ted: Jan 502 Bad 04F0 2047 6174 6577 6179 6d6f 6465 2d63 6861 Gatewaymode-cha 0500 6e67 652d 7065 7269 6f64 3d0d 0a61 3d6f nge-period=..a=o 0510 7269 656e 743a 7365 6173 6361 7065 0d0a rient:seascape.. 0520 613d 7479 7065 3a6d 6f64 6572 6174 6564 a=type:moderated 0530 3430 3420 4e6f 7420 466f 756e 6433 3035 404 Not Found305 0540 2055 7365 2050 726f 7879 0d0a 613d 7479 Use Proxy..a=ty
0550 7065 3a72 6563 766f 6e6c 790d 0a61 3d74 pe:recvonly..a=t 0560 7970 653a 6d65 6574 696e 670d 0a6b 3d70 ype:meeting..k=p 0570 726f 6d70 743a 0d0a 5265 6665 7272 6564 rompt:..Referred 0580 2d42 793a 200d 0a49 6e2d 5265 706c 792d -By: ..In-Reply- 0590 546f 3a20 5452 5545 6e63 6f64 696e 673a To: TRUEncoding: 05A0 2031 3832 2051 7565 7565 6441 7574 6865 182 QueuedAuthe 05B0 6e74 6963 6174 653a 200d 0a55 7365 722d nticate: ..User- 05C0 4167 656e 743a 200d 0a61 3d66 7261 6d65 Agent: ..a=frame 05D0 7261 7465 3a0d 0a41 6c65 7274 2d49 6e66 rate:..Alert-Inf 05E0 6f3a 2043 414e 4345 4c20 0d0a 613d 6d61 o: CANCEL ..a=ma 05F0 7870 7469 6d65 3a3b 7265 7472 792d 6166 xptime:;retry-af 0600 7465 723d 7561 6368 616e 6e65 6c73 3d34 ter=uachannels=4 0610 3130 2047 6f6e 650d 0a52 6566 6572 2d54 10 Gone..Refer-T 0620 6f3a 200d 0a50 7269 6f72 6974 793a 200d o: ..Priority: . 0630 0a6d 3d63 6f6e 7472 6f6c 200d 0a61 3d71 .m=control ..a=q 0640 7561 6c69 7479 3a0d 0a61 3d73 6470 6c61 uality:..a=sdpla 0650 6e67 3a0d 0a61 3d63 6861 7273 6574 3a0d ng:..a=charset:. 0660 0a52 6570 6c61 6365 733a 2052 4546 4552 .Replaces: REFER 0670 2069 7073 6563 2d69 6b65 3b74 7261 6e73 ipsec-ike;trans 0680 706f 7274 3d0d 0a61 3d6b 6579 7764 733a port=..a=keywds: 0690 0d0a 6b3d 6261 7365 3634 3a3b 7265 6672 ..k=base64:;refr 06A0 6573 6865 723d 0d0a 613d 7074 696d 653a esher=..a=ptime: 06B0 0d0a 6b3d 636c 6561 723a 3b72 6563 6569 ..k=clear:;recei 06C0 7665 643d 3b64 7572 6174 696f 6e3d 0d0a ved=;duration=.. 06D0 4163 6365 7074 3a20 0d0a 613d 6772 6f75 Accept: ..a=grou 06E0 703a 4641 4c53 453a 2049 4e46 4f20 0d0a p:FALSE: INFO .. 06F0 4163 6365 7074 2d0d 0a61 3d6c 616e 673a Accept-..a=lang: 0700 0d0a 6d3d 6461 7461 206d 6f64 652d 7365 ..m=data mode-se 0710 743d 0d0a 613d 746f 6f6c 3a54 4c53 756e t=..a=tool:TLSun 0720 2c20 0d0a 4461 7465 3a20 0d0a 613d 6361 , ..Date: ..a=ca 0730 743a 0d0a 6b3d 7572 693a 0d0a 5072 6f78 t:..k=uri:..Prox 0740 792d 3b72 6561 736f 6e3d 3b6d 6574 686f y-;reason=;metho 0750 643d 0d0a 613d 6d69 643a 3b6d 6164 6472 d=..a=mid:;maddr 0760 3d6f 7061 7175 653d 0d0a 4d69 6e2d 3b61 =opaque=..Min-;a 0770 6c67 3d4d 6f6e 2c20 5475 652c 2057 6564 lg=Mon, Tue, Wed 0780 2c20 4672 692c 2053 6174 2c20 3b74 746c , Fri, Sat, ;ttl 0790 3d61 7574 733d 0d0a 723d 0d0a 7a3d 0d0a =auts=..r=..z=.. 07A0 653d 3b69 643d 0d0a 693d 6372 633d 0d0a e=;id=..i=crc=.. 07B0 753d 3b71 3d75 6173 3431 3420 5265 7175 u=;q=uas414 Requ 07C0 6573 742d 5552 4920 546f 6f20 4c6f 6e67 est-URI Too Long 07D0 6976 6575 7072 6976 6163 7975 6470 7265 iveuprivacyudpre 07E0 6665 7236 3030 2042 7573 7920 4576 6572 fer600 Busy Ever 07F0 7977 6865 7265 7175 6972 6564 3438 3020 ywherequired480 0800 5465 6d70 6f72 6172 696c 7920 556e 6176 Temporarily Unav 0810 6169 6c61 626c 650d 0a61 3d74 7970 653a ailable..a=type: 0820 482e 3333 3230 3220 4163 6365 7074 6564 H.33202 Accepted 0830 0d0a 5365 7373 696f 6e2d 4578 7069 7265 ..Session-Expire 0840 733a 200d 0a53 7562 7363 7269 7074 696f s: ..Subscriptio
0850 6e2d 5374 6174 653a 204e 6f76 200d 0a53 n-State: Nov ..S 0860 6572 7669 6365 2d52 6f75 7465 3a20 5365 ervice-Route: Se 0870 7020 0d0a 416c 6c6f 772d 4576 656e 7473 p ..Allow-Events 0880 3a20 4665 6220 0d0a 613d 696e 6163 7469 : Feb ..a=inacti 0890 7665 5254 502f 5341 5650 2052 5450 2f41 veRTP/SAVP RTP/A 08A0 5650 4620 416e 6f6e 796d 6f75 7369 7073 VPF Anonymousips 08B0 3a0d 0a61 3d74 7970 653a 7465 7374 656c :..a=type:testel 08C0 3a4d 4553 5341 4745 200d 0a61 3d72 6563 :MESSAGE ..a=rec 08D0 766f 6e6c 790d 0a61 3d73 656e 646f 6e6c vonly..a=sendonl 08E0 790d 0a63 3d49 4e20 4950 3420 0d0a 5265 y..c=IN IP4 ..Re 08F0 6173 6f6e 3a20 0d0a 416c 6c6f 773a 200d ason: ..Allow: . 0900 0a45 7665 6e74 3a20 0d0a 5061 7468 3a20 .Event: ..Path: 0910 3b75 7365 723d 0d0a 623d 4153 2043 5420 ;user=..b=AS CT 0920 0d0a 5757 572d 4175 7468 656e 7469 6361 ..WWW-Authentica 0930 7465 3a20 4469 6765 7374 200d 0a61 3d73 te: Digest ..a=s 0940 656e 6472 6563 7669 6465 6f63 7465 742d endrecvideoctet- 0950 616c 6967 6e3d 6170 706c 6963 6174 696f align=applicatio 0960 6e2f 7364 7061 7468 6561 6465 7273 7061 n/sdpatheaderspa 0970 7574 683d 0d0a 613d 6f72 6965 6e74 3a70 uth=..a=orient:p 0980 6f72 7472 6169 7469 6d65 6f75 7474 722d ortraitimeouttr- 0990 696e 7469 636f 6e63 3d34 3833 2054 6f6f inticonc=483 Too 09A0 204d 616e 7920 486f 7073 6c69 6e66 6f70 Many Hopslinfop 09B0 7469 6f6e 616c 676f 7269 7468 6d3d 3630 tionalgorithm=60 09C0 3420 446f 6573 204e 6f74 2045 7869 7374 4 Does Not Exist 09D0 2041 6e79 7768 6572 6573 706f 6e73 653d Anywheresponse=
09F0 6f73 6974 696f 6e3a 204d 4435 3830 2050 osition: MD580 P 0A00 7265 636f 6e64 6974 696f 6e20 4661 696c recondition Fail 0A10 7572 6570 6c61 6365 7334 3232 2053 6573 ureplaces422 Ses 0A20 7369 6f6e 2049 6e74 6572 7661 6c20 546f sion Interval To 0A30 6f20 536d 616c 6c6f 6361 6c31 3831 2043 o Smallocal181 C 0A40 616c 6c20 4973 2042 6569 6e67 2046 6f72 all Is Being For 0A50 7761 7264 6564 6f6d 6169 6e3d 6661 696c wardedomain=fail 0A60 7572 656e 6465 7265 616c 6d3d 5355 4253 urenderealm=SUBS 0A70 4352 4942 4520 7072 6563 6f6e 6469 7469 CRIBE preconditi 0A80 6f6e 6f72 6d61 6c69 7073 6563 2d6d 616e onormalipsec-man 0A90 6461 746f 7279 3431 3320 5265 7175 6573 datory413 Reques 0AA0 7420 456e 7469 7479 2054 6f6f 204c 6172 t Entity Too Lar 0AB0 6765 3265 3138 3320 5365 7373 696f 6e20 ge2e183 Session 0AC0 5072 6f67 7265 7373 6374 7034 3836 2042 Progressctp486 B 0AD0 7573 7920 4865 7265 6d6f 7465 726d 696e usy Heremotermin 0AE0 6174 6564 414b 4176 312d 4d44 352d 7365 atedAKAv1-MD5-se 0AF0 7373 696f 6e6f 6e65 0d0a 4175 7468 6f72 ssionone..Author 0B00 697a 6174 696f 6e3a 2036 3033 2044 6563 ization: 603 Dec 0B10 6c69 6e65 7874 6e6f 6e63 653d 3438 3520 linextnonce=485 0B20 416d 6269 6775 6f75 7365 726e 616d 653d Ambiguousername= 0B30 6175 6469 6f0d 0a43 6f6e 7465 6e74 2d54 audio..Content-T 0B40 7970 653a 204d 6172 200d 0a52 6563 6f72 ype: Mar ..Recor
0B50 642d 526f 7574 653a 204a 756c 2034 3031 d-Route: Jul 401 0B60 2055 6e61 7574 686f 7269 7a65 640d 0a52 Unauthorized..R 0B70 6571 7569 7265 3a20 0d0a 743d 3020 302e equire: ..t=0 0. 0B80 302e 302e 300d 0a53 6572 7665 723a 2052 0.0.0..Server: R 0B90 4547 4953 5445 5220 0d0a 633d 494e 2049 EGISTER ..c=IN I 0BA0 5036 2031 3830 2052 696e 6769 6e67 3130 P6 180 Ringing10 0BB0 3020 5472 7969 6e67 763d 300d 0a6f 3d55 0 Tryingv=0..o=U 0BC0 5044 4154 4520 4e4f 5449 4659 200d 0a53 PDATE NOTIFY ..S 0BD0 7570 706f 7274 6564 3a20 756e 6b6e 6f77 upported: unknow 0BE0 6e41 4d52 5450 2f41 5650 200d 0a50 7269 nAMRTP/AVP ..Pri 0BF0 7661 6379 3a20 0d0a 5365 6375 7269 7479 vacy: ..Security 0C00 2d0d 0a45 7870 6972 6573 3a20 0d0a 613d -..Expires: ..a= 0C10 7274 706d 6170 3a0d 0a6d 3d76 6964 656f rtpmap:..m=video 0C20 200d 0a6d 3d61 7564 696f 200d 0a73 3d20 ..m=audio ..s= 0C30 6661 6c73 650d 0a61 3d63 6f6e 663a 3b65 false..a=conf:;e 0C40 7870 6972 6573 3d0d 0a52 6f75 7465 3a20 xpires=..Route: 0C50 0d0a 613d 666d 7470 3a0d 0a61 3d63 7572 ..a=fmtp:..a=cur 0C60 723a 436c 6965 6e74 3a20 5665 7269 6679 r:Client: Verify 0C70 3a20 0d0a 613d 6465 733a 0d0a 5241 636b : ..a=des:..RAck 0C80 3a20 0d0a 5253 6571 3a20 4259 4520 636e : ..RSeq: BYE cn 0C90 6f6e 6365 3d31 3030 7265 6c75 7269 3d71 once=100reluri=q 0CA0 6f70 3d54 4350 5544 5071 6f73 786d 6c3b op=TCPUDPqosxml; 0CB0 6c72 0d0a 5669 613a 2053 4950 2f32 2e30 lr..Via: SIP/2.0 0CC0 2f54 4350 2034 3038 2052 6571 7565 7374 /TCP 408 Request 0CD0 2054 696d 656f 7574 696d 6572 7073 6970 Timeoutimerpsip 0CE0 3a0d 0a43 6f6e 7465 6e74 2d4c 656e 6774 :..Content-Lengt 0CF0 683a 204f 6374 200d 0a56 6961 3a20 5349 h: Oct ..Via: SI 0D00 502f 322e 302f 5544 5020 3b63 6f6d 703d P/2.0/UDP ;comp= 0D10 7369 6763 6f6d 7072 6f62 6174 696f 6e61 sigcomprobationa 0D20 636b 3b62 7261 6e63 683d 7a39 6847 3462 ck;branch=z9hG4b 0D30 4b0d 0a4d 6178 2d46 6f72 7761 7264 733a K..Max-Forwards: 0D40 2041 7072 2053 4354 5052 4143 4b20 494e Apr SCTPRACK IN 0D50 5649 5445 200d 0a43 616c 6c2d 4944 3a20 VITE ..Call-ID: 0D60 0d0a 436f 6e74 6163 743a 2032 3030 204f ..Contact: 200 O 0D70 4b0d 0a46 726f 6d3a 200d 0a43 5365 713a K..From: ..CSeq: 0D80 200d 0a54 6f3a 203b 7461 673d 0410 dd10 ..To: ;tag=....
12E0 4604 0ce1 F...
Table 1: binary representation of the static SIP/SDP
dictionary for SigComp
Security Considerations
The security considerations of [1] apply. This memo does not introduce any known additional security risk.
IANA Considerations
None.
Acknowledgements
The authors would like to thank Lars-Erik Jonsson, Zhigang C. Liu and Jonathan Rosenberg for their valuable comments.
References
Normative References
[1] Price, R., Bormann, C., Christoffersson, J., Hannu, H., Liu, Z.
and J. Rosenberg, "Signaling Compression (SigComp)", RFC 3320, January 2003.
[2] Bradner, S., "Key words for use in RFCs to indicate requirement
levels", BCP 14, RFC 2119, March 1997.
Informative References
[3] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
Peterson, J., Sparks, R., Handley, M. and E. Schooler, "SIP:
Session Initiation Protocol", RFC 3261, June 2002.
[4] Garcia-Martin, M., "3rd-Generation Partnership Project (3GPP)
Release 5 requirements on the Session Initiation Protocol
(SIP)", Work in Progress.
[5] Yergeau, F., "UTF-8, a transformation format of ISO 10646", RFC
2279, January 1998.
[6] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S.,
Leach, P., Luotonen, A. and L. Stewart, "HTTP Authentication:
Basic and Digest Access Authentication", RFC 2617, June 1999.
[7] Vaha-Sipila, A., "URLs for telephone calls", RFC 2806, April
2000.
[8] Donovan, S., "The SIP INFO Method", RFC 2976, October 2000.
[9] Roach, A. B., "Session Initiation Protocol (SIP)-Specific Event
Notification", RFC 3265, June 2002.
[10] Rosenberg, J. and H. Schulzrinne, "Reliability of Provisional
Responses in Session Initiation Protocol (SIP)", RFC 3262, June 2002.
[11] Rosenberg, J., "The Session Initiation Protocol UPDATE Method",
RFC 3311, October 2002.
[12] Camarillo, G., Ed., Marshall, W., Ed. and J. Rosenberg,
"Integration of Resource Management and Session Initiation
Protocol (SIP)", RFC 3312, October 2002.
[13] Sparks, R., "The SIP Refer Method", Work in Progress.
[14] Mahy, R., Biggs, B. and R. Dean, "The Session Initiation
Protocol (SIP) "Replaces" Header", Work in Progress.
[15] Sparks, R., "Internet Media Type message/sipfrag", RFC 3420,
November 2002.
[16] Willis, D. and B. Hoeneisen, "Session Initiation Protocol (SIP)
Extension Header Field for Registering Non-Adjacent Contacts",
RFC 3327, December 2002.
[17] Schulzrinne, H., Oran, D. and G. Camarillo, "The Reason Header
Field for the Session Initiation Protocol (SIP)", RFC 3326, December 2002.
[18] Donovan, S., and J. Rosenberg, "Session Timers in the Session
Initiation Protocol (SIP)", Work in Progress.
[19] Niemi, A., Arkko, J. and V. Torvinen , "Hypertext Transfer
Protocol (HTTP) Digest Authentication Using Authentication and
Key Agreement (AKA)", RFC 3310, September 2002.
[20] Arkko, J., Torvinen, V., Camarillo, G., Niemi A. and T. Haukka,
"Security Mechanism Agreement for the Session Initiation
Protocol (SIP)", RFC 3329, January 2003.
[21] Campbell, B., Rosenberg, J., Schulzrinne, H., Huitema, C. and
D. Gurle, "Session Initiation Protocol (SIP) Extension for
Instant Messaging", RFC 3428, December 2002.
[22] Schulzrinne, H. and J. Rosenberg, "Session Initiation Protocol
(SIP) Caller Preferences and Callee Capabilities", Work in
Progress.
[23] Camarillo, G., "Compressing the Session Initiation Protocol
(SIP)", RFC 3486, February 2003.
[24] Handley, M., Jacobson, V. and C. Perkins, "SDP: Session
Description Protocol", Work in Progress.
[25] Sjoberg, J., Westerlund, M., Lakaniemi, A. and Q. Xie, "Real-
Time Transport Protocol payload format and file storage format
for the Adaptive Multi-Rate (AMR) and Adaptive Multi-Rate
Wideband (AMR-WB) audio codecs", RFC 3267, June 2002.
[26] Camarillo, G., Eriksson, G., Holler, J. and H. Schulzrinne,
"Grouping of Media Lines in the Session Description Protocol
(SDP)", RFC 3388, December 2002.
[27] Schulzrinne, H. and S. Petrack, "RTP Payload for DTMF Digits,
Telephony Tones and Telephony Signals", RFC 2833, May 2000.
[28] Arkko, J., Carrara, E., Lindholm, F., Naslund, M. and K.
Norrman, "Key Management Extensions for SDP and RTSP", Work in
Progress.
[29] Arkko, J., Carrara, E., Lindholm, F., Naslund, M. and K.
Norrman, "MIKEY: Multimedia Internet KEYing", Work in
Progress.
[30] Baugher, M., Blom, R., Carrara, E., McGrew, D., Naslund, M.,
Norrman, K. and D. Oran, "The Secure Real Time Transport
Protocol", Work in Progress.
[31] Ott, J., Wenger, S., Fukunaga, S., Sato, N., Burmeister, C.,
and Rey, J., "Extended RTP Profile for RTCP-based feedback
(RTP/AVPF)", Work in Progress.
[32] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with
Session Description Protocol (SDP)", RFC 3264, June 2002.
[33] Peterson, J., "A Privacy Mechanism for the Session Initiation
Protocol (SIP)", RFC 3323, November 2002.
[34] Sparks, R., "The Referred-By mechanism", Work in Progress.
[35] Willis, D. and B. Hoeneisen, "Session Initiation Protocol
Extension Header Field for Service Route Discovery During
Registration", Work in Progress.
Appendix A. SIP input strings to the SIP/SDP static dictionary
For reference, this section lists the SIP input strings that were used in generating the dictionary, as well as a priority value, the offset of the string in the generated dictionary, the length of the string, and one or more references into the referenced documents that motivate the presence of this string. Note that the notation "[CRLF]" stands for a sequence of two bytes with the values 0x0d and 0x0a, respectively.
The priority value is used for determining the position of the string in the dictionary. Lower priority values (higher priorities) cause the string to occur at a later position in the dictionary, making it more efficient to reference the string in certain compression algorithms. Hence, lower priority values were assigned to strings more likely to occur.
String Pr Off Len References
=============================== == ==== ==== ====
"sip:" 1 0CDD 0004 [3] 19.1.1 "sips:" 3 08AC 0005 [3] 19.1.1 "tel:" 3 08BD 0004 [7] 2.2 "SIP/2.0" 1 0CB9 0007 [3] 25.1 "SIP/2.0/UDP " 1 0CFE 000C [3] 25.1 "SIP/2.0/TCP " 2 0CB9 000C [3] 25.1 "INVITE" 1 0D4E 0006 [3] 25.1 "INVITE " 1 0D4E 0007 [3] 25.1 "ACK" 1 0D4A 0003 [3] 25.1 "ACK " 1 0D4A 0004 [3] 25.1 "OPTIONS" 4 0269 0007 [3] 25.1 "OPTIONS " 4 0269 0008 [3] 25.1 "BYE" 2 0C8A 0003 [3] 25.1 "BYE " 2 0C8A 0004 [3] 25.1 "CANCEL" 4 05E3 0006 [3] 25.1 "CANCEL " 4 05E3 0007 [3] 25.1 "REGISTER" 2 0B8F 0008 [3] 25.1 "REGISTER " 2 0B8F 0009 [3] 25.1 "INFO" 4 06E9 0004 [8] 2 "INFO " 4 06E9 0005 [8] 2 "SUBSCRIBE" 2 0A6C 0009 [9] 8.1.1 "SUBSCRIBE " 2 0A6C 000A [9] 8.1.1 "NOTIFY" 2 0BC6 0006 [9] 8.1.2 "NOTIFY " 2 0BC6 0007 [9] 8.1.2 "PRACK" 2 0D48 0005 [10] 6 "PRACK " 2 0D48 0006 [10] 6 "UPDATE" 2 0BBF 0006 [11] 7, 10 "UPDATE " 2 0BBF 0007 [11] 7, 10 "REFER" 4 066B 0005 [13] 2.1, 7
"REFER " 4 066B 0006 [13] 2.1, 7 "MESSAGE" 3 08C1 0007 [21] 9 "MESSAGE " 3 08C1 0008 [21] 9 "[CRLF]Accept: " 4 06CE 000A [3] 20.1 "[CRLF]Accept-" 4 06EE 0009 [22] 5,
[3] 20.2, 20.3
"Contact: " 5 0009 0009 [22] 5 "Encoding: " 4 0597 000A [3] 20.2,
[3] 20.12
"Language: " 4 0271 000A [3] 20.3,
[3] 20.13
"[CRLF]Alert-Info: " 4 05D5 000E [3] 20.4 "[CRLF]Allow: " 3 08F6 0009 [3] 20.5 "[CRLF]Allow-Events: " 3 0872 0010 [9] 8.2.1 "[CRLF]Authentication-Info: " 4 0293 0017 [3] 20.6 "[CRLF]Authorization: " 2 0AF8 0011 [3] 20.7 "[CRLF]Call-ID: " 1 0D55 000B [3] 20.8 "[CRLF]Call-Info: " 5 002D 000D [3] 20.9 "[CRLF]Contact: " 1 0D60 000B [3] 20.10 "[CRLF]Content-" 4 0B35 000A [3] 20.11,
20.12, 20.13, [3] 20.14,
20.15
"Disposition: " 4 09EC 000D [3] 20.11 "Encoding: " 4 0597 000A [3] 20.2,
[3] 20.12
"Language: " 4 0271 000A [3] 20.3,
[3] 20.13
"[CRLF]Content-Length: " 1 0CE1 0012 [3] 20.14 "[CRLF]Content-Type: " 2 0B35 0010 [3] 20.15 "[CRLF]CSeq: " 1 0D79 0008 [3] 20.16 "[CRLF]Date: " 4 0722 0008 [3] 20.17 "[CRLF]Error-Info: " 5 0012 000E [3] 20.18 "[CRLF]Event: " 3 08FF 0009 [9] 8.2.1 "[CRLF]Expires: " 2 0C01 000B [3] 20.19 "[CRLF]From: " 1 0D71 0008 [3] 20.20 "[CRLF]In-Reply-To: " 4 0585 000F [3] 20.21 "[CRLF]Max-Forwards: " 1 0D31 0010 [3] 20.22 "[CRLF]Min-" 4 0768 0006 [3] 20.23,
[18] 5
"Expires: " 4 083A 0009 [3] 20.23 "SE: " 4 06E5 0004 [18] 5 "[CRLF]MIME-Version: " 5 0469 0010 [3] 20.24 "[CRLF]Organization: " 5 048E 0010 [3] 20.25 "[CRLF]Path: " 3 0908 0008 [16] 3 "[CRLF]Priority: " 4 0623 000C [3] 20.26 "[CRLF]Privacy: " 2 0BEB 000B [33] 4.2 "[CRLF]Proxy-" 4 073A 0008 [3] 20.27,
20.28, 20.29
"Authenticate: " 4 05AB 000E [3] 20.27 "Authorization: " 4 0AFA 000F [3] 20.28 "Require: " 4 0B6F 0009 [3] 20.29 "[CRLF]RAck: " 2 0C7A 0008 [10] 7.2 "[CRLF]Reason: " 3 08EC 000A [17] 2 "[CRLF]Record-Route: " 2 0B49 0010 [3] 20.30 "[CRLF]Refer-To: " 4 0617 000C [13] 2.1, 7 "[CRLF]Referred-By: " 4 0576 000F [34] 9 "[CRLF]Reject-Contact: " 5 0000 0012 [22] 5 "[CRLF]Replaces: " 4 065F 000C [14] 3.1 "[CRLF]Reply-To: " 5 003A 000C [3] 20.31 "[CRLF]Request-Disposition: " 4 09E2 0017 [22] 5 "[CRLF]Require: " 2 0B6D 000B [3] 20.32 "[CRLF]Retry-After: " 4 03A8 000F [3] 20.33 "[CRLF]Route: " 2 0C47 0009 [3] 20.34 "[CRLF]RSeq: " 2 0C82 0008 [10] 7.1 "[CRLF]Security-" 2 0BF6 000B [20] 3.3 "Client: " 2 0C62 0008 [20] 3.3 "Server: " 2 0B87 0008 [20] 3.3 "Verify: " 2 0C6A 0008 [20] 3.3 "[CRLF]Server: " 4 0B85 000A [3] 20.35 "[CRLF]Service-Route: " 3 085D 0011 [35] "[CRLF]Session-Expires: " 3 0830 0013 [18] 4 "[CRLF]Subject: " 5 0051 000B [3] 20.36 "[CRLF]Subscription-State: " 3 0843 0016 [9] 8.2.3 "[CRLF]Supported: " 2 0BCD 000D [3] 20.37 "[CRLF]Timestamp: " 5 0020 000D [3] 20.38 "[CRLF]To: " 1 0D81 0006 [3] 20.39 "[CRLF]Unsupported: " 4 04D6 000F [3] 20.40 "[CRLF]User-Agent: " 4 05B9 000E [3] 20.41 "[CRLF]Via: " 1 0CB2 0007 [3] 20.42 "[CRLF]Via: SIP/2.0/UDP " 1 0CF7 0013 [3] 20.42 "[CRLF]Via: SIP/2.0/TCP " 1 0CB2 0013 [3] 20.42 "[CRLF]Warning: " 5 0046 000B [3] 20.43 "[CRLF]WWW-Authenticate: " 2 0920 0014 [3] 20.44 "[CRLF]WWW-Authenticate: Digest " 2 0920 001B [3] 20.44 "[CRLF][CRLF]" 2 09E0 0004 [3] 7 ";transport=" 4 067A 000B [3] 25.1 "udp" 4 07DB 0003 [3] 25.1,
[24] A, [3] 25.1, [24] A
"tcp" 4 04C1 0003 [3] 25.1 "sctp" 4 0AC7 0004 [3] 25.1 "tls" 4 04D3 0003 [3] 25.1,
[20] 3.3
";user=" 3 0910 0006 [3] 25.1 "phone" 3 00F2 0005 [3] 25.1 "ip" 4 008D 0002 [3] 25.1 ";method=" 4 074A 0008 [3] 25.1
";ttl=" 4 078C 0005 [3] 25.1 ";lr" 2 0CAF 0003 [3] 25.1 "Digest " 2 0934 0007 [6] 3.2.1,
3.2.2
"username=" 2 0B27 0009 [6] 3.2.2 "uri=" 2 0C9B 0004 [6] 3.2.2 "qop=" 2 0C9F 0004 [6] 3.2.1,
3.2.2
"cnonce=" 2 0C8E 0007 [6] 3.2.2 "nc=" 2 0996 0003 [6] 3.2.2 "response=" 2 09D7 0009 [6] 3.2.2 "nextnonce=" 2 0B12 000A [6] 3.2.3 "rspauth=" 2 096C 0008 [6] 3.2.3 "realm=" 2 0A66 0006 [6] 3.2.1 "domain=" 2 0A55 0007 [6] 3.2.1 "nonce=" 2 0B16 0006 [6] 3.2.1 "opaque=" 4 0761 0007 [6] 3.2.1 "stale=" 4 0148 0006 [6] 3.2.1 "true" 4 03F4 0004 [6] 3.2.1 "false" 4 0C30 0005 [6] 3.2.1 "algorithm=" 2 09B4 000A [6] 3.2.1,
[19] 3.1
"MD5" 2 09F9 0003 [6] 3.2.1,
[19] 3.1
"MD5-sess" 2 0AEA 0008 [6] 3.2.1,
[19] 3.1
"auth" 4 031E 0004 [6] 3.2.1 "auth-int" 4 031E 0008 [6] 3.2.1 "AKAv" 2 0AE4 0004 [19] 3.1, 6 "AKAv1-MD5" 2 0AE4 0009 [19] 3.1, 6 "auts=" 4 0791 0005 [19] 3.4 "digest-integrity" 4 00CA 0010 [20] 3.3 "ipsec-ike" 4 0671 0009 [20] 3.3 "ipsec-man" 4 0A87 0009 [20] 3.3 "smime" 4 0098 0005 [20] 3.3 ";alg=" 4 076E 0005 [20] 3.3 ";purpose=" 5 006B 0009 [3] 20.9 "icon" 5 0993 0004 [3] 20.9, 20.11 "info" 5 09AB 0004 [3] 20.9 "card" 5 0081 0004 [3] 20.9 ";expires=" 2 0C3E 0009 [3] 25.1,
[9] 8.4
"render" 5 0A61 0006 [3] 20.11 "session" 5 0AEE 0007 [3] 20.11,
[33] 4.2
"alert" 5 04BD 0005 [3] 20.11 ";handling=" 5 005C 000A [3] 20.11 "optional" 2 09AE 0008 [3] 20.11,
[12] 4, [3] 20.11, [12] 4
"required" 5 07F4 0008 [3] 20.11 "text" 5 007C 0004 [3] 25.1 "image" 5 0066 0005 [3] 25.1 "audio" 5 0B30 0005 [3] 25.1 "video" 5 0946 0005 [3] 25.1 "application" 2 0334 000B [3] 25.1 "application/sdp" 2 0956 000F [3] 25.1 "message/sip" 4 009B 000B [3] 27.5 "message/sipfrag" 4 009B 000F [15] 2 "message" 4 009B 0007 [3] 27.5,
[15] 2
"sip" 4 00A3 0003 [3] 27.5 "sipfrag" 4 00A3 0007 [15] 2 "multipart/signed" 4 0398 0010 [3] 23.3 "multipart" 4 0398 0009 [3] 25.1, 7.4.1 "sdp" 2 064B 0003 "xml" 2 0CAC 0003 "Mon, " 4 0773 0005 [3] 25.1 "Tue, " 4 0778 0005 [3] 25.1 "Wed, " 4 077D 0005 [3] 25.1 "Thu, " 4 03B9 0005 [3] 25.1 "Fri, " 4 0782 0005 [3] 25.1 "Sat, " 4 0787 0005 [3] 25.1 "Sun, " 4 071D 0005 [3] 25.1 " Jan " 4 04E4 0005 [3] 25.1 " Feb " 4 0881 0005 [3] 25.1 " Mar " 4 0B44 0005 [3] 25.1 " Apr " 4 0D40 0005 [3] 25.1 " May " 4 0478 0005 [3] 25.1 " Jun " 4 049D 0005 [3] 25.1 " Jul " 4 0B58 0005 [3] 25.1 " Aug " 4 033F 0005 [3] 25.1 " Sep " 4 086D 0005 [3] 25.1 " Oct " 4 0CF2 0005 [3] 25.1 " Nov " 4 0858 0005 [3] 25.1 " Dec " 4 02A9 0005 [3] 25.1 " GMT" 4 03B6 0004 [3] 25.1 ";tag=" 1 0D87 0005 [3] 25.1 "emergency" 4 018C 0009 [3] 20.26 "urgent" 4 021A 0006 [3] 20.26 "normal" 4 0A81 0006 [3] 20.26 "non-urgent" 4 0216 000A [3] 20.26 ";duration=" 4 06C4 000A [3] 20.33 ";maddr=" 4 075A 0007 [3] 20.42 ";received=" 4 06BA 000A [3] 20.42 ";branch=" 5 0D22 0008 [3] 20.42 ";branch=z9hG4bK" 1 0D22 000F [3] 8.1.1.7
"SIP" 5 0CB9 0003 [3] 25.1,
[17] 2
"UDP" 2 0CA6 0003 [3] 20.42 "TCP" 2 0CA3 0003 [3] 20.42 "TLS" 4 071B 0003 [3] 20.42 "SCTP" 4 0D45 0004 [3] 20.42 "active" 4 088C 0006 [9] 8.4 "pending" 4 01AD 0007 [9] 8.4 "terminated" 4 0ADA 000A [9] 8.4 ";reason=" 4 0742 0008 [9] 8.4 ";retry-after=" 4 05F7 000D [9] 8.4 "deactivated" 4 011C 000B [9] 8.4 "probation" 4 0D16 0009 [9] 8.4 "rejected" 4 01C9 0008 [9] 8.4 "timeout" 4 0986 0007 [9] 8.4 "giveup" 4 07CF 0006 [9] 8.4 "noresource" 4 024D 000A [9] 8.4 ";id=" 4 07A2 0004 [9] 8.4 "100rel" 2 0C95 0006 [10] 8.1 "precondition" 2 0A76 000C [12] 8 "refer" 3 07DE 0005 [13] 3.1, 7 "to-tag" 4 028D 0006 [14] 3.2 "from-tag" 4 01E6 0008 [14] 3.2 "replaces" 4 0A11 0008 [14] 3.4 "Q.850" 5 01EE 0005 [17] 2 ";cause=" 5 0074 0007 [17] 2 ";text=" 5 007B 0006 [17] 2 "path" 3 0964 0004 [16] 3 ";refresher=" 4 069B 000B [18] 4 "uac" 4 0604 0003 [18] 4 "uas" 4 07B5 0003 [18] 4 "timer" 4 0CD7 0005 [18] 7.1 "pref" 5 07DD 0004 [22] 4.1 "TRUE" 4 0594 0004 [22] 6.2 "FALSE" 4 06E2 0005 [22] 6.2 ";q=" 4 07B2 0003 [3] 25.1,
[22] 6.2, [20] 3.3
";comp=sigcomp" 1 0D0A 000D [23] 6 "privacy" 3 07D4 0007 [33] 4.2 "header" 4 0967 0006 [33] 4.2 "user" 4 0911 0004 [33] 4.2 "none" 2 0AF4 0004 [33] 4.2,
[12] 4
"critical" 4 04B7 0008 [33] 4.2 "100 " 5 0BAE 0004 [3] 21.1.1 "100 Trying" 2 0BAE 000A [3] 21.1.1 "180 " 5 0BA3 0004 [3] 21.1.2 "180 Ringing" 2 0BA3 000B [3] 21.1.2
"181 " 5 0A3B 0004 [3] 21.1.3 "181 Call Is Being Forwarded" 4 0A3B 001B [3] 21.1.3 "182 " 5 05A1 0004 [3] 21.1.4 "182 Queued" 4 05A1 000A [3] 21.1.4 "183 " 5 0AB4 0004 [3] 21.1.5 "183 Session Progress" 2 0AB4 0014 [3] 21.1.5 "200 " 5 0D6B 0004 [3] 21.2.1 "200 OK" 1 0D6B 0006 [3] 21.2.1 "202 " 5 0824 0004 [9] 8.3.1 "202 Accepted" 3 0824 000C [9] 8.3.1 "300 " 5 0085 0004 [3] 21.3.1 "300 Multiple Choices" 4 0085 0014 [3] 21.3.1 "301 " 5 0383 0004 [3] 21.3.2 "301 Moved Permanently" 4 0383 0015 [3] 21.3.2 "302 " 5 036E 0004 [3] 21.3.3 "302 Moved Temporarily" 4 036E 0015 [3] 21.3.3 "305 " 5 053D 0004 [3] 21.3.4 "305 Use Proxy" 4 053D 000D [3] 21.3.4 "380 " 5 02AE 0004 [3] 21.3.5 "380 Alternative Service" 4 02AE 0017 [3] 21.3.5 "400 " 5 03E6 0004 [3] 21.4.1 "400 Bad Request" 4 03E6 000F [3] 21.4.1 "401 " 5 0B5D 0004 [3] 21.4.2 "401 Unauthorized" 2 0B5D 0010 [3] 21.4.2 "402 " 5 03BE 0004 [3] 21.4.3 "402 Payment Required" 4 03BE 0014 [3] 21.4.3 "403 " 5 020A 0004 [3] 21.4.4 "403 Forbidden" 4 020A 000D [3] 21.4.4 "404 " 5 0530 0004 [3] 21.4.5 "404 Not Found" 4 0530 000D [3] 21.4.5 "405 " 5 02F2 0004 [3] 21.4.6 "405 Method Not Allowed" 4 02F2 0016 [3] 21.4.6 "406 " 5 041E 0004 [3] 21.4.7 "406 Not Acceptable" 4 041E 0012 [3] 21.4.7 "407 " 5 00AA 0004 [3] 21.4.8 "407 Proxy Authentication Required" 4 00AA 0021 [3] 21.4.8 "408 " 5 0CC5 0004 [3] 21.4.9 "408 Request Timeout" 4 0CC5 0013 [3] 21.4.9 "410 " 5 060F 0004 [3] 21.4.10 "410 Gone" 4 060F 0008 [3] 21.4.10 "413 " 5 0A96 0004 [3] 21.4.11 "413 Request Entity Too Large" 4 0A96 001C [3] 21.4.11 "414 " 5 07B8 0004 [3] 21.4.12 "414 Request-URI Too Long" 4 07B8 0018 [3] 21.4.12 "415 " 5 0195 0004 [3] 21.4.13 "415 Unsupported Media Type" 4 0195 001A [3] 21.4.13 "416 " 5 0175 0004 [3] 21.4.14 "416 Unsupported URI Scheme" 4 0175 001A [3] 21.4.14
"420 " 5 023D 0004 [3] 21.4.15 "420 Bad Extension" 4 023D 0011 [3] 21.4.15 "421 " 5 02DC 0004 [3] 21.4.16 "421 Extension Required" 4 02DC 0016 [3] 21.4.16 "422 " 5 0A19 0004 [18] 6, 12.1 "422 Session Interval Too Small" 4 0A19 001E [18] 6, 12.2 "423 " 5 01D1 0004 [3] 21.4.17 "423 Interval Too Brief" 4 01D1 0016 [3] 21.4.17 "429 " 5 0220 0004 [34] 9 "429 Provide Referror Identity" 4 0220 001D [34] 9 "480 " 5 07FC 0004 [3] 21.4.18 "480 Temporarily Unavailable" 3 07FC 001B [3] 21.4.18 "481 " 5 0127 0004 [3] 21.4.19 "481 Call/Transaction Does Not Exist" 4 0127 0023 [3] 21.4.19 "482 " 5 047D 0004 [3] 21.4.20 "482 Loop Detected" 4 047D 0011 [3] 21.4.20 "483 " 5 0999 0004 [3] 21.4.21 "483 Too Many Hops" 4 0999 0011 [3] 21.4.21 "484 " 5 00DA 0004 [3] 21.4.22 "484 Address Incomplete" 4 00DA 0016 [3] 21.4.22 "485 " 5 0B1C 0004 [3] 21.4.23 "485 Ambiguous" 4 0B1C 000D [3] 21.4.23 "486 " 5 0ACB 0004 [3] 21.4.24 "486 Busy Here" 3 0ACB 000D [3] 21.4.24 "487 " 5 0308 0004 [3] 21.4.25 "487 Request Terminated" 4 0308 0016 [3] 21.4.25 "488 " 5 01B4 0004 [3] 21.4.26 "488 Not Acceptable Here" 4 01B4 0017 [3] 21.4.26 "489 " 5 04C7 0004 [9] 8.3.2 "489 Bad Event" 4 04C7 000D [9] 8.3.2 "491 " 5 03F8 0004 [3] 21.4.27 "491 Request Pending" 4 03F8 0013 [3] 21.4.27 "493 " 5 0457 0004 [3] 21.4.28 "493 Undecipherable" 4 0457 0012 [3] 21.4.28 "494 " 5 00FE 0004 [20] 3.3.1 "494 Security Agreement Required" 4 00FE 001F [20] 3.3.1 "500 " 5 014E 0004 [3] 21.5.1 "500 Server Internal Error" 4 014E 0019 [3] 21.5.1 "501 " 5 040B 0004 [3] 21.5.2 "501 Not Implemented" 4 040B 0013 [3] 21.5.2 "502 " 5 04E9 0004 [3] 21.5.3 "502 Bad Gateway" 4 04E9 000F [3] 21.5.3 "503 " 5 02C5 0004 [3] 21.5.4 "503 Service Unavailable" 4 02C5 0017 [3] 21.5.4 "504 " 5 027B 0004 [3] 21.5.5 "504 Server Time-out" 4 027B 0013 [3] 21.5.5 "505 " 5 01F1 0004 [3] 21.5.6 "505 Version Not Supported" 4 01F1 0019 [3] 21.5.6
"513 " 5 0344 0004 [3] 21.5.7 "513 Message Too Large" 4 0344 0015 [3] 21.5.7 "580 " 5 09FB 0004 [12] 8 "580 Precondition Failure" 4 09FB 0018 [12] 8 "600 " 5 07E3 0004 [3] 21.6.1 "600 Busy Everywhere" 3 07E3 0013 [3] 21.6.1 "603 " 5 0B09 0004 [3] 21.6.2 "603 Decline" 4 0B09 000B [3] 21.6.2 "604 " 5 09BE 0004 [3] 21.6.3 "604 Does Not Exist Anywhere" 4 09BE 001B [3] 21.6.3 "606 " 5 0430 0004 [3] 21.6.4 "606 Not Acceptable" 4 0430 0012 [3] 21.6.4 "687 " 5 0359 0004 [14] 3.5 "687 Dialog Terminated" 4 0359 0015 [14] 3.5 "Anonymous" 3 08A4 0009 [3] 8.1.1.3
Table A.1: SIP input strings for the SIP/SDP dictionary
Appendix B. SDP input strings to the SIP/SDP static dictionary
For reference, this section lists the SDP input strings that were used in generating the dictionary, as well as a priority value, the offset of the string in the generated dictionary, the length of the string, and one or more references into the referenced documents that motivate the presence of this string. Note that the notation "[CRLF]" stands for a sequence of two bytes with the values 0x0d and 0x0a, respectively.
The priority value is used for determining the position of the string in the dictionary. Lower priority values (higher priorities) cause the string to occur at a later position in the dictionary, making it more efficient to reference the string in certain compression algorithms. Hence, lower priority values were assigned to strings more likely to occur.
String Pr Off Len References
=============================== == ==== ==== ====
"v=0[CRLF]o=" 2 0BB8 0007 [24] 6 "[CRLF]s=" 2 0C2B 0004 [24] 6 "[CRLF]s= " 2 0C2B 0005 [32] 5 "[CRLF]i=" 4 07A6 0004 [24] 6 "[CRLF]u=" 4 07AE 0004 [24] 6 "[CRLF]e=" 4 079E 0004 [24] 6 "[CRLF]c=IN IP4 " 3 08E1 000B [24] 6 "[CRLF]c=IN IP6 " 2 0B98 000B [24] 6 "[CRLF]c=" 5 08E1 0004 [24] 6 "[CRLF]b=" 3 0916 0004 [24] 6 "[CRLF]t=" 2 0B78 0004 [24] 6 "[CRLF]t=0 0" 2 0B78 0007 [32] 5 "[CRLF]r=" 4 0796 0004 [24] 6 "[CRLF]z=" 4 079A 0004 [24] 6 "[CRLF]k=clear:" 4 06B0 000A [24] 6 "[CRLF]k=base64:" 4 0690 000B [24] 6 "[CRLF]k=uri:" 4 0732 0008 [24] 6 "[CRLF]k=prompt:" 4 056B 000B [24] 6 "[CRLF]k=" 5 056B 0004 [24] 6 "[CRLF]a=cat:" 4 072A 0008 [24] 6 "[CRLF]a=keywds:" 4 0685 000B [24] 6 "[CRLF]a=tool:" 4 0712 0009 [24] 6 "[CRLF]a=ptime:" 4 06A6 000A [24] 6 "[CRLF]a=maxptime:" 4 05EA 000D [24] 6 "[CRLF]a=rtpmap:" 2 0C0C 000B [24] 6, [32] 5 "[CRLF]a=recvonly" 3 08C9 000C [24] 6 "[CRLF]a=sendrecv" 3 093B 000C [24] 6 "[CRLF]a=sendonly" 3 08D5 000C [24] 6 "[CRLF]a=inactive" 3 0886 000C [24] 6
"[CRLF]a=orient:portrait" 4 0974 0013 [24] 6 "[CRLF]a=orient:landscape" 4 03D2 0014 [24] 6 "[CRLF]a=orient:seascape" 4 050B 0013 [24] 6 "[CRLF]a=type:broadcast" 4 0442 0012 [24] 6 "[CRLF]a=type:meeting" 4 055B 0010 [24] 6 "[CRLF]a=type:moderated" 4 051E 0012 [24] 6 "[CRLF]a=type:test" 4 08B1 000D [24] 6 "[CRLF]a=type:H.332" 4 0817 000E [24] 6 "[CRLF]a=type:recvonly" 4 054A 0011 [24] 6 "[CRLF]a=charset:" 4 0653 000C [24] 6 "[CRLF]a=sdplang:" 4 0647 000C [24] 6 "[CRLF]a=lang:" 4 06F7 0009 [24] 6 "[CRLF]a=framerate:" 4 05C7 000E [24] 6 "[CRLF]a=quality:" 4 063B 000C [24] 6 "[CRLF]a=fmtp:" 2 0C50 0009 [24] 6 "[CRLF]a=curr:" 2 0C59 0009 [12] 4 "[CRLF]a=des:" 2 0C72 0008 [12] 4 "[CRLF]a=conf:" 2 0C35 0009 [12] 4 "[CRLF]a=mid:" 4 0752 0008 [26] 3 "[CRLF]a=group:" 4 06D8 000A [26] 3 "[CRLF]a=key-mgmt:mikey" 4 0257 0012 [28] 2.1,
[29] 6
"[CRLF]a=key-mgmt:" 4 0257 000D [28] 2.1 "[CRLF]a=" 5 0257 0004 [24] 6 "[CRLF]m=audio " 2 0C21 000A [24] 6 "[CRLF]m=video " 2 0C17 000A [24] 6 "[CRLF]m=application " 4 0330 0010 [24] 6 "[CRLF]m=data " 4 0700 0009 [24] 6 "[CRLF]m=control " 4 062F 000C [24] 6 "[CRLF]m=" 5 0330 0004 [24] 6 "AS " 3 091A 0003 [24] 6 "CT " 3 091D 0003 [24] 6 "RTP/AVP " 2 0BE3 0008 [24] A "RTP/SAVP " 3 0892 0009 [30] 12 "RTP/AVPF " 3 089B 0009 [31] 4.1 "udp" 4 07DB 0003 [3] 25.1,
[24] A, [3] 25.1, [24] A
"0.0.0.0" 4 0B7E 0007 [24] A "qos" 2 0CA9 0003 [12] 4 "mandatory" 2 0A8D 0009 [12] 4 "optional" 2 09AE 0008 [3] 20.11,
[12] 4, [3] 20.11, [12] 4
"none" 2 0AF4 0004 [33] 4.2,
[12] 4
"failure" 4 0A5C 0007 [12] 4 "unknown" 4 0BDA 0007 [12] 4 "e2e" 2 0AB1 0003 [12] 4 "local" 2 0A36 0005 [12] 4
"remote" 2 0AD6 0006 [12] 4 "send" 2 08D9 0004 [12] 4 "recv" 2 0553 0004 [12] 4 "sendrecv" 2 093F 0008 [12] 4 "AMR" 2 0BE1 0003 [25] 8 "octet-align=" 4 094A 000C [25] 8 "mode-set=" 4 0709 0009 [25] 8 "mode-change-period=" 4 04F8 0013 [25] 8 "mode-change-neighbor=" 4 04A2 0015 [25] 8 "crc=" 4 07AA 0004 [25] 8 "robust-sorting=" 4 0166 000F [25] 8 "interleaving=" 4 0323 000D [25] 8 "channels=" 4 0606 0009 [25] 8 "octet-align" 4 094A 000B [25] 8 "telephone-event" 4 00EE 000F [27] 3.3, 6.1 "events" 4 00F8 0006 [27] 6.1 "rate" 4 052B 0004 [27] 6.1, 6.2 "tone" 4 0453 0004 [27] 6.2 "rtcp-fb" 4 04C0 0007 [31] 4 "ack" 4 0D1F 0003 [31] 4 "nack" 4 0D1E 0004 [31] 4 "ttr-int" 4 098C 0007 [31] 4 "app" 4 0334 0003 [31] 4 "rpsi" 4 0CDB 0004 [31] 4 "pli" 4 0336 0003 [31] 4 "sli" 4 09A9 0003 [31] 4
Table B.1: SDP input strings for the SIP/SDP dictionary
Authors' Addresses
Miguel A. Garcia-Martin Ericsson Hirsalantie 11 FIN-02420, Jorvas, Finland
Phone: +358 9299 3553 EMail: [email protected]
Carsten Bormann Universitaet Bremen TZI Postfach 330440 D-28334 Bremen, Germany
Phone: +49 421 218 7024 EMail: [email protected]
Joerg Ott Universitaet Bremen TZI Postfach 330440 D-28334 Bremen, Germany
Phone: +49.421.201-7028 EMail: [email protected]
Richard Price Roke Manor Research Ltd Romsey, Hants, SO51 0ZN, United Kingdom
Phone: +44 1794 833681 EMail: [email protected]
Adam Roach dynamicsoft 5100 Tennyson Parkway, Suite 1200 Plano, TX 75024, USA
EMail: [email protected]
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