Cisco Systems RFC 2543 and RFC 3261 Server User Manual

A P P E N D I X
A
SIP Compliance
This appendix describes Cisco SIP proxy server (Cisco SPS) compliance with the Internet Engineering
Task Force (IETF) definition of Session Initiation Protocol (SIP) as described in the following RFCs.
RFC1
Title
2543
SIP: Session Initiation Protocol (March 1999)
3261
SIP: Session Initiation Protocol (June 2002)
3263
SIP: Locating SIP Servers (June 2002)
1. Not all supported RFCs are listed.
Contents
•
RFC 2543 and RFC 3261
– SIP Functions, page A-2
– SIP Methods, page A-2
– SIP Responses, page A-2
– SIP Header Fields, page A-6
– SIP Transport Layer Protocols, page A-7
– SIP Security, page A-8
•
RFC 3263
– SIP DNS Records Usage, page A-8
Cisco SIP Proxy Server Administrator Guide
A-1
Appendix A
SIP Compliance
RFC 2543 and RFC 3261
RFC 2543 and RFC 3261
SIP Functions
Table A-1
SIP Functions
Function
Supported?
Proxy server
Yes (transaction stateful, parallel forking, and
recursive)
Redirect server
Yes
Registrar server
Yes
SIP Methods
Cisco SPS supports five of the six methods used by SIP. It handles unknown methods such as
NEWMETHOD in the same manner as known methods such as OPTIONS and REFER.
Table A-2
SIP Methods
Method
Supported?
Cisco SPS Action
ACK
Yes
Forwards ACK requests.1
BYE
Yes
Forwards BYE requests.
CANCEL
Yes
Forwards CANCEL requests.2
INFO
Yes
Forwards INFO requests.
INVITE
Yes
Forwards INVITE requests.
NOTIFY
Yes
Forwards NOTIFY requests.
OPTIONS
Yes
Responds to OPTIONS requests.
REFER
Yes
Forwards REFER requests.
REGISTER
Yes
Supports both user and device registration.
SUBSCRIBE
Yes
Forwards SUBSCRIBE requests.
UPDATE
Yes
Forwards UPDATE requests.
1. The SPS can generate a local ACK for a non-200 OK final response to an INVITE request.
2. The SPS can generate a local CANCEL for a pending branch when it receives a 200 OK or 6xx response from the branch.
SIP Responses
Cisco SPS supports the following SIP responses:
•
1xx Response—Information Responses
•
2xx Response—Successful Responses
•
3xx Response—Redirection Responses
•
4xx Response—Request Failure Responses
Cisco SIP Proxy Server Administrator Guide
A-2
Appendix A
SIP Compliance
RFC 2543 and RFC 3261
Table A-3
•
5xx Response—Server Failure Responses
•
6xx Response—Global Responses
SIP Responses
SIP Response
Meaning
Supported?
Cisco SPS Action
1xx Response—Information Responses
100
Trying
Action is being taken on behalf of the
caller, but the called party is not yet
located.
Yes
Generates and forwards this
response for an incoming
INVITE. Upon receiving this
response, waits for a 180
Ringing, 183 Session progress,
or 200 OK response.
180
Ringing
Called party is located and is being
notified of the call.
Yes
Forwards this response.
181
Call is being forwarded Call is being rerouted to another
destination.
182
Queued
Called party is not currently available or Yes
elects to queue the call rather than reject
it.
183
Session progress
System performs inband alerting for the Yes
caller.
Yes
2xx Response—Successful Responses
200
OK
Request has been successfully
Yes
processed. The action taken depends on
the request made.
Generates this response to a
REGISTER or CANCEL
request. Otherwise forwards this
response.
3xx Response—Redirection Responses
300
Multiple choices
Yes
Address resolves to more than one
location. All locations are provided and
the user or UA can select which location
to use.
Does not generate this response.
If recursive is enabled, recurses
on all contacts; otherwise
forwards this response.
301
Moved permanently
User is no longer available at the
Yes
specified location. An alternate location
is included in the header.
302
Moved temporarily
User is temporarily unavailable at the
Yes
specified location. An alternate location
is included in the header.
In redirect mode, generates this
response when it locates one or
more contacts. In proxy mode, if
recursive is enabled, recurses on
all contacts; otherwise forwards
this response.
305
Use proxy
Caller must use a proxy to contact the
called party.
Yes
380
Alternative service
Call is unsuccessful, but alternative
services are available.
Yes
Does not generate this response.
If recursive is enabled, recurses
on all contacts; otherwise
forwards this response.
Cisco SIP Proxy Server Administrator Guide
A-3
Appendix A
SIP Compliance
RFC 2543 and RFC 3261
Table A-3
SIP Responses (continued)
SIP Response
Meaning
Supported?
Cisco SPS Action
4xx Response—Request Failure Responses
400
Bad Request
Request can not be understood because Yes
of an illegal format.
Generates and forwards this
response.
401
Unauthorized
Request requires user authentication.
Yes
Forwards this response. If it is
configured as a registrar and
authentication is enabled,
generates this response.
402
Payment required
Payment is required for server to
complete the call.
See Cisco SPS
action
403
Forbidden
Server has received and understood the
request but will not provide the service.
In registrar mode and if proxied
by the proxy server, generates
this response.
404
Not found
Server has definite information that the Yes
user does not exist in the specified
domain.
Generates and forwards this
response.
405
Method not allowed
See Cisco SPS
Method specified in the request is not
allowed. The response contains a list of action
allowed methods.
Forwards this response.
406
Not acceptable
Requested resource can generate only
responses that have unacceptable
content as specified in the accept header
of the request.
407
Proxy authentication
required
Similar to the 401 Unauthorized
response, but client must first
authenticate itself with the proxy.
Yes
Forwards this response. If
authentication is enabled,
generates this response.
408
Request timeout
Server could not produce a response
before the expiration timeout.
See Cisco SPS
action
Generates and forwards this
response.
409
Conflict
Request cannot be processed because of
a conflict with the current state of the
resource.
410
Gone
A resource is no longer available at the See Cisco SPS
server and no forwarding address is
action
known.
411
Length required
User refuses to accept the request
without a defined content length.
413
See Cisco SPS
Request entity too large Server refuses to process the request
action
because it is larger than the server is
willing or able to process. If a retry after
header field is contained in this
response, the user can attempt the call
once again in the retry time provided.
414
Request-URI too long
Yes
Server refuses to process the request
Yes
because the Request-URI is too long for
the server to interpret.
Cisco SIP Proxy Server Administrator Guide
A-4
Forwards this response.
Generates and forwards this
response.
Appendix A
SIP Compliance
RFC 2543 and RFC 3261
Table A-3
SIP Responses (continued)
SIP Response
Meaning
Supported?
Cisco SPS Action
415
Unsupported media
Server refuses to process the request
because the format of the body is not
supported by the destination endpoint.
Yes
Forwards this response.
420
Bad extension
Server cannot understand the protocol
extension indicated in the Require
header.
Yes
Generates and forwards this
response.
480
Temporarily
unavailable
Called party was contacted but is
temporarily unavailable.
Yes
Forwards this response. If
preauthentication is enabled and
fails, generates this response.
481
Call leg/transaction
does not exist
Server ignores the request because it is Yes
either a BYE for which there is no
matching leg ID or a CANCEL for
which there is no matching transaction.
482
Loop detected
Server received a request that includes
itself in the path.
483
Too many hops
Server received a request that requires
more hops than allowed by the
Max-Forwards header.
484
Address incomplete
Server received a request that contains
an incomplete address.
485
Ambiguous
Server received a request that contains
an ambiguous called-party address. It
can provide possible alternative
addresses.
486
Busy here
Called party was contacted but his or
her system is unable to take additional
calls.
487
Busy here; request
cancelled
Request was terminated by a BYE or
CANCEL request.
Yes
488
Not acceptable media
An error in handling the request
occurred.
See Cisco SPS
action
See Cisco SPS
action
Generates and forwards this
response.
Forwards this response.
Cisco SIP Proxy Server Administrator Guide
A-5
Appendix A
SIP Compliance
RFC 2543 and RFC 3261
Table A-3
SIP Responses (continued)
SIP Response
Meaning
Supported?
Cisco SPS Action
Yes
Generates and forwards this
response.
5xx Response—Server Failure Responses
500
Server internal error
Server or gateway encountered an
unexpected error that prevents it from
processing the request.
501
Not implemented
Server or gateway does not support the
functions required to complete the
request.
502
Bad gateway
Server or gateway received an invalid
response from a downstream server.
See Cisco SPS
action
Forwards this response.
503
Service unavailable
Server or gateway is unable to process
the request due to an overload or
maintenance problem.
Yes
Generates and forwards this
response.
504
Gateway timeout
Server or gateway did not receive a
timely response from another server
(such as a location server).
See Cisco SPS
action
Forwards this response.
505
Version not supported
Server or gateway does not support the Yes
version of the SIP protocol used in the
request.
6xx Response—Global Responses
600
Busy everywhere
Called party was contacted but is busy
and cannot take the call at this time.
603
Decline
Called party was contacted but cannot
or does not want to participate in the
call.
604
Does not exist anywhere Server has authoritative information
that the called party does not exist in the
network.
606
Not acceptable
See Cisco SPS
action
Forwards this response.
Called party was contacted, but some
aspect of the session description was
unacceptable.
SIP Header Fields
Note
All SIP header fields that concern the Cisco SPS are correctly handled and parsed except for the Hide
and Encryption header fields. Header fields that do not directly affect the Cisco SPS or that are unknown
to it are passed unaltered in the SIP request.
Cisco SIP Proxy Server Administrator Guide
A-6
Appendix A
SIP Compliance
RFC 2543 and RFC 3261
Table A-4
SIP Header Fields
Header Field
Supported?
Header Field
Supported?
Accept
Yes
Organization
Yes
Accept-Encoding
Yes
MIME-Version
Yes
Accept-Language
Yes
Priority
Yes
Alert-Info
Yes
Proxy-Authenticate
Yes
Allow
Yes
Proxy Authorization
Yes
Also
Yes
Proxy-Require
Yes
Authorization
Yes
Record-Route
Yes
Call-ID
Yes
Require
Yes
Call-Info
Yes
Response-Key
Yes
Contact
Yes
Retry-After
Yes
Content-Disposition
Yes
Route
Yes
Content-Encoding
Yes
Server
Yes
Content-Length
Yes
Subject
Yes
Content-Type
Yes
Supported
Yes
Cseq
Yes
Timestamp
Yes
Yes
To
Yes
No
Unsupported
Yes
Error-Info
Yes
User-Agent
Yes
Expires
Yes
Via
Yes
From
Yes
Warning
Yes
In-Reply-To
Yes
WWW-Authenticate
Yes
Max-Forwards
Yes
Date
Encryption
1
1. When a SIP message is received that contains this header field, the message is processed with the field ignored.
SIP Transport Layer Protocols
Table A-5
SIP Transport Layer Protocols
Transport Layer Protocol
Supported?
Unicast UDP
Yes
Multicast UDP
No
TCP
Yes
TLS
Yes
Cisco SIP Proxy Server Administrator Guide
A-7
Appendix A
RFC 3263
SIP Security
Table A-6
SIP Security
Mode
Supported?
Encryption Mode
End-to-end
No
Hop-by-Hop
Yes
Authentication Mode
Basic1
Yes
Digest
Yes
Proxy
Yes
1. Due to its weak security, basic authentication has been deprecated. This is a
change from RFC 2543. It is not disabled or removed from Cisco SPS, but will no
longer be supported or extended to interwork with new or modified functionality.
We strongly discourage the use of basic authentication.
RFC 3263
SIP DNS Records Usage
Table A-7
SIN DNS Records Usage
DNS Resource Record Type
Supported?
A
Yes
NAPTR
Yes
SRV
Yes
Cisco SIP Proxy Server Administrator Guide
A-8
SIP Compliance
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