PM35951: UNNECESSARY FLOW TOKEN IN THE RECORD-ROUTE

Fixes are available

APAR status

Closed as program error.

Error description

The Session Initiation Protocol (SIP) Container should not
create a flow-token for an initial INVITE request sent by
non-SIP outbound client.

Local fix

Problem summary

****************************************************************
* USERS AFFECTED:  Session Initiation Protocol (SIP) users     *
*                  of IBM WebSphere Application Server V7.0    *
****************************************************************
* PROBLEM DESCRIPTION: The server applies RFC 5626             *
*                      ("outbound") processing to a request,   *
*                      although the client is not "outbound"   *
*                      enabled.                                *
****************************************************************
* RECOMMENDATION:                                              *
****************************************************************
The problem occurs when the Websphere Application Server SIP
container acts as a proxy/registrar between two elements, a
client and an edge proxy, in a call flow such as this:

   Alice   NAT   Edge Proxy   Proxy/Registrar    Bob
     |      |       |              |              |
1    |-- REGISTER ->|              |              |
2    |      |       |-- REGISTER ->|              |
3    |      |       |<-- 200 OK ---|              |
4    |<-- 200 OK ---|              |              |
5    |      |       |              |<-- INVITE ---|
6    |      |       |<-- INVITE ---|              |

In step 1, Alice, who resides behind a NAT (network address
translator), registers itself by sending a REGISTER, through
the NAT, indicating support for RFC 5626 ("outbound").
In step 2, the edge proxy creates a flow token (as specified
in RFC 5626 chapter 5) and sets the flow token in a new Path
header field that it pushes onto the forwarded REGISTER message.
In step 5, Bob attempts to call Alice through the proxy. Bob
does not indicate support for RFC 5626.
In step 6, the proxy/registrar forwards the INVITE downstream.
It pushes a Route header field value onto the outgoing INVITE
message, copying the Path URI that it received in step 2 into
the new Route. This URI contains a flow token. This is normal.
But when the underlying SIP container forwards the INVITE, it
adds a Record-Route with another flow token, which describes
the connection with Bob. This is an error, because Bob has not
indicated "outbound" support.

This is a violation of RFC 5626 (5.3) specifying that the
procedure is only applied if the proxy is the host in the
topmost Route header field value, and the Route header field
value contains a flow token.

As the top Route does not match the proxy/registrar host, the
SIP container must ignore it, and send out the INVITE without
applying "outbound" processing.

Problem conclusion

The problem is fixed in the SIP container code. With this fix,
RFC 5626 (5.3.2) processing is only applied if the top Route
matches the local host.

The fix for this APAR is currently targeted for inclusion in
fix pack 7.0.0.19.  Please refer to the Recommended Updates
page for delivery information:
http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980

Temporary fix

Comments

APAR Information

APAR number
PM35951
Reported component name
WEBSPHERE APP S
Reported component ID
5724J0800
Reported release
700
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt
Submitted date
2011-03-30
Closed date
2011-05-04
Last modified date
2011-05-04

APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:

Fix information

Fixed component name
WEBSPHERE APP S
Fixed component ID
5724J0800

Applicable component levels

R700 PSY
UP

[{"Business Unit":{"code":"BU059","label":"IBM Software w\/o TPS"},"Product":{"code":"SSEQTP","label":"WebSphere Application Server"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"7.0","Line of Business":{"code":"LOB45","label":"Automation"}}]

Document Information

Modified date:
27 October 2021

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PM35951: UNNECESSARY FLOW TOKEN IN THE RECORD-ROUTE

Fixes are available

Subscribe

APAR status

Closed as program error.

Error description

Local fix

Problem summary

Problem conclusion

Temporary fix

Comments

APAR Information

APAR number

Reported component name

Reported component ID

Reported release

Status

PE

HIPER

Special Attention

Submitted date

Closed date

Last modified date

APAR is sysrouted FROM one or more of the following:

APAR is sysrouted TO one or more of the following:

Fix information

Fixed component name

Fixed component ID

Applicable component levels

R700 PSY

Document Information

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