1. Configuration Guide
  2. RCS Services
  3. MSRP B2BUA Support for NG911
  4. MSRP Message Size Limiting

MSRP Message Size Limiting

To set a limit on the Message Session Relay Protocol (MSRP) size of the message that the Oracle® Enterprise Session Border Controller (ESBC) can receive from a given realm, the tcp-media-profile configuration includes the msrp-message-size, msrp-message-size-file, and msrp-message-size-enforce options. The ESBC supports this functionality only on Virtual Machines.

The maximum size of the MSRP messages that an MSRP Back to Back User Agent (B2BUA) can receive is advertised:
  • in the signaling plane - in the SDP a=max-size attribute
  • in the data plane - in the MSRP Byte-Range header.
The msrp-message-size parameter sets the size limit for interactive messages. The default is 0, which means that the ESBC does not intervene in limiting the size for the interactive message. The valid range is 0-4194304 bytes. When the msrp-message-size-file value is greater than zero, the ESBC:
  • fills in the SDP offer-answer and a=max-size attribute, if missing.
  • adjusts its value to the configured limits, if the value of the SDP a=max-size attribute exceeds the limit.
The msrp-message-size-file parameter sets the size limits for file transfer over MSRP that includes an SDP a=file-selector attribute. A file transfer over MSRP is identified by the presence of the SDP a=file-selector attribute in the MSRP media description. The default is 0, which means the ESBC does not intervene in limiting the size for the file transfer. The valid range is 0-4294967295. Note that a file is transferred in the MSRP message in message/cpim format. You can set the msrp-message-size-file to a larger value than the maximum file to be transferred to provide room for the message/cpim header. (512 to 1024 bytes fits most scenarios.) When the msrp-message-size-file value is greater than zero, the ESBC:
  • fills in the SDP offer-answer a=max-size attribute, if missing.
  • adjusts its value to the configured limit, if the value of the SDP a=max-size attribute exceeds the limit.

The msrp-message-size-enforce parameter, when enabled, performs byte counting on the MSRP messages to enforce compliance with the negotiated maximum MSRP message size. The negotiated maximum MSRP message size is the minimum between the SDP a=max-size attribute value (if one is provided by the B2BUA) and the configured value for msrp-message-size or msrp-message-size-file. If the ESBC detects that the actual size of the MSRP chunk does not match the negotiated maximum size, it immediately stops forwarding the chunk. When the MSRP session is a file transfer, the SIP session terminates by sending a BYE on both the originating and the terminating legs.

Note:

The maximum negotiated size applies to MSRP chunks rather than MSRP messages.