Table Of Contents

Configuring SIP SDP Attribute Passthrough

Restrictions for Configuring SIP SDP Attribute Passthrough

Information about SIP SDP Attribute Passthrough

Configuring SIP SDP Attribute Passthrough

Example of SIP SDP Attribute Passthrough

Configuring SIP SDP Attribute Passthrough

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Before ACE SBC release 3.1.00, the SBC handled SDP attribute passthrough by passing through all attribute lines (a=) on an Offer (sometimes changing or adding certain kinds of attribute lines).

For attribute lines on an Answer, the SBC passed through certain select lines (while ignoring the rest) and reflecting back the offerer's lines instead.

For ACE SBC release 3.1.00, the Session Border Controller (SBC) by default passes through all a= lines in SIP messages containing SDP offers and answers that it forwards. You can also configure the SBC to block certain a= lines, either by specifying a whitelist (a finite set of a=lines that are passed through, with all others blocked), or alternatively a blacklist (a finite set of a=lines that are blocked, with all others passed through).

Feature History for SIP Attribute Passthrough

Release	Modification
ACE SBC Release 3.1.00	SDP Attribute Passthrough was introduced on the Cisco7600 series router .

Restrictions for Configuring SIP SDP Attribute Passthrough

Review the following restrictions forSIP SDP Attribute Passthrough:

•The existing reflect behavior is not supported.

•Wildcard or prefix matching of attribute lines is not supported.

•Distinguishing media-level from session-level a-lines for the purposes of matching is not supported.

•Sophisticated matching conditions (for example, apply only to video streams or apply only to offers) are not supported.

•Attribute blocking in media bypass calls is not supported.

•Blocking function is restricted to unknown attributes.

•The following attributes are ignored by unknown attribute policy because this may interfere with the correct operation of the SBC.

–a=rtpmap

–a=fmtp

–a=sendonly

–a=recvonly

–a=inactive

–a=sendrecv

–a=ptime

–a=mid

–a=group

–a=curr

–a=des

–a=conf

–a=crypto.

At the point where the policy is applied, a (rate-limited) warning log is issued if the policy attempts to delete one of these lines.

Information about SIP SDP Attribute Passthrough

Additional per-call storage is needed to store the SDP policy that is being applied. This is expected to be ~160 bytes per call.

Configuring SIP SDP Attribute Passthrough

This section contains the steps for implementing SIP SDP attribute passthrough.

SUMMARY STEPS

1. configure

2. sbc service-name

3. sbe

4. sdp-match-table table-name

5. action whitelist/blacklist

6. match-string name

7. match-string name

8. exit

9. sdp-match-table table-name

10. action whitelist/blacklist

11. match-string name

12. match-string name

13. exit

14. sdp-policy-table table-name

15. match-table table-name

16. exit

17. sdp-policy-table table-name

18. match-table table-name

19. exit

20. cac-policy-set number

21. first-cac-table table-name

22. first-cac-scope scope

23. cac-table table-name

24. match-type type

25. entry number

26. match-value value

27. action action-name

28. caller-inbound-policy policytab-name

29. caller-outbound-policy policytab-name

30. callee-inbound-policy policytab-name

31. callee-outbound-policy policytab-name

32. exit

33. exit

34. complete

35. exit

36. active-cac-policy-set number

37. show services sbc service-name sbe cac-policy-set number table number entry number

DETAILED STEPS

	Command or Action	Purpose
Step 1	configure Example: host1/Admin# configure	Enables global configuration mode.
Step 2	sbc service-name Example: host1/Admin(config)# sbc mysbc	Enters the mode of an SBC service. •Use the service-name argument to define the name of the service.
Step 3	sbe Example: host1/Admin(config-sbc)# sbe	Enters the mode of the signaling border element (SBE) function of the SBC.
Step 4	sdp-match-table table-name Example: host1/Admin(config-sbc-sbe)# sdp-match-table 1	Adds an existing sdp-match-table into policy.
Step 5	action whitelist/blacklist Example: host1/Admin(config-sbc-sbe-sdp-match-tbl)# ac- tion blacklist	Specifies an SDP policy table action.
Step 6	match-string name Example: host1/Admin(config-sbc-sbe-sdp-match-tbl)# match-string attribute-name1	Configures an SDP attribute matching string.
Step 7	match-string name Example: host1/Admin(config-sbc-sbe-sdp-match-tbl)# match-string attribute-name2	Configures an SDP attribute matching string.
Step 8	exit Example: host1/Admin(config-sbc-sbe-sdp-match-tbl)# exit	Returns to the previous submode.
Step 9	sdp-match-table table-name Example: host1/Admin(config-sbc-sbe)# sdp-match-table-name 2	Adds an existing sdp-match-table into policy.
Step 10	action whitelist/blacklist Example: host1/Admin(config-sbc-sbe-sdp-match-tbl)# ac- tion blacklist	Adds an action allowing a defined set of attributes and blocking the remaining attributes.
Step 11	match-string name Example: host1/Admin(config-sbc-sbe-sdp-match-tbl)# match-string attribute-name1	Configures an SDP attribute matching string.
Step 12	match-string name Example: host1/Admin(config-sbc-sbe-sdp-match-tbl)# match-string attribute-name3	Configures an SDP attribute matching string.
Step 13	exit Example: host1/Admin(config-sbc-sbe-sdp-match-tbl)# exit	Returns to the previous submode.
Step 14	sdp-policy-table table-name Example: host1/Admin(config-sbc-sbe)# sdp-policy-table ta- ble-name1	Configures an SDP policy table.
Step 15	match-table table-name Example: host1/Admin(config-sbc-sbe-sdp-policy-tbl)# match-table table-name1	Configure an SDP match table used in a policy.
Step 16	exit Example: host1/Admin(config-sbc-sbe-sip-adj)# exit	Returns to the previous submode.
Step 17	sdp-policy-table table-name Example: host1/Admin(config-sbc-sbe)# sdp-policy-table ta- ble-name2	Configures an SDP policy table.
Step 18	match-table table-name Example: host1/Admin(config-sbc-sbe-sdp-policy-tbl)# match-table table-name2	Configure an SDP match table used in a policy.
Step 19	exit Example: host1/Admin(config-sbc-sbe-sip-adj)# exit	Returns to the previous submode.
Step 20	cac-policy-set number Example: host1/Admin(config-sbc-sbe)# cac-policy-set 1	Enters the submode of CAC policy set configuration.
Step 21	first-cac-table table-name Example: host1/Admin(config-sbc-sbe-cacpolicy)# first-cac-table RootCacTable	Configures the name of the first policy table to process when performing the admission control stage of policy.
Step 22	first-cac-scope scope Example: host1/Admin(config-sbc-sbe-cacpolicy)# first-cac-scope src-adjacency	Configures the scope at which to begin defining limits when performing the admission control stage of policy.
Step 23	cac-table table-name Example: host1/Admin(config-sbc-sbe-cacpolicy)# cac-table RootCacTable	Creates or configures an admission control table.
Step 24	match-type type Example: host1/Admin(config-sbc-sbe-cacpolicy-cactable)# match-type call-priority	Configures a new CAC table type that enables the priority of the call to be used as a criterion in CAC policy.
Step 25	entry number Example: host1/Admin(config-sbc-sbe-cacpolicy-cactable)# entry 1	Creates or modifies an entry in a table.
Step 26	match-value value Example: host1/Admin(config-sbc-sbe-cacpolicy-cactable-en- try)# match-value sipp1	Configures the match type of an admission control table.
Step 27	action action-name Example: host1/Admin(config-sbc-sbe-cacpolicy-cactable-en- try)# action cac-complete	Specifies the action to take if this entry is chosen.
Step 28	caller-inbound-policy policytab-name Example: host1/Admin(config-sbc-sbe-cacpolicy-cactable-en- try)# caller-inbound-policy foo	Configures a caller inbound SDP policy table.
Step 29	caller-outbound-policy policytab-name Example: host1/Admin(config-sbc-sbe-cacpolicy-cactable-en- try)# caller-outbound-policy foo	Configures a caller outbound SDP policy table.
Step 30	callee-inbound-policy policytab-name Example: host1/Admin(config-sbc-sbe-cacpolicy-cactable-en- try)# callee-inbound-policy foo2	Configures a callee inbound SDP policy table.
Step 31	callee-outbound-policy policytab-name Example: host1/Admin(config-sbc-sbe-cacpolicy-cactable-en- try)# callee-outbound-policy foo2	Configures a callee outbound SDP policy table.
Step 32	exit Example: host1/Admin(config-sbc-sbe-cacpolicy-cactable-en- try)# exit	Returns to the previous submode.
Step 33	exit Example: host1/Admin(config-sbc-sbe-cacpolicy-cactable)# exit	Returns to the previous submode.
Step 34	complete Example: host1/Admin(config-sbc-sbe-cacpolicy)# complete	Performs a consistency check on the CAC policy set.
Step 35	exit Example: host1/Admin(config-sbc-sbe-cacpolicy)# exit	Returns to the previous submode.
Step 36	active-cac-policy-set number Example: host1/Admin(config-sbc-sbe)# active-cac-poli- cy-set 1	Enters the active CAC policy set.
Step 37	show services sbc service-name sbe cac-poli- cy-set number table number entry number Example: host1/Admin(config-sbc-sbe)# show services sbc mysbc sbe cac-policy-set 1 table RootCacTable en- try 1	Displays detailed information for a given entry in a CAC policy table.

Example of SIP SDP Attribute Passthrough

This section provides a sample configuration and output for SIP SDP Attribute Passthrough.

host1/Admin# config t

Enter configuration commands, one per line.  End with CNTL/Z.

host1/Admin(config)# sbc interwork

host1/Admin(config-sbc)# sbe

host1/Admin(config-sbc-sbe)# sdp-match-table matchtab1

host1/Admin(config-sbc-sbe-sdp-match-tbl)# action blacklist

host1/Admin(config-sbc-sbe-sdp-match-tbl)# match-string X-sqn

host1/Admin(config-sbc-sbe-sdp-match-tbl)# match-string X-cap

host1/Admin(config-sbc-sbe-sdp-match-tbl)# exit

host1/Admin(config-sbc-sbe)# sdp-match-table matchtab2

host1/Admin(config-sbc-sbe-sdp-match-tbl)# action blacklist

host1/Admin(config-sbc-sbe-sdp-match-tbl)# match-string X-sqn

host1/Admin(config-sbc-sbe-sdp-match-tbl)# match-string X-pc-csuites-rtp

host1/Admin(config-sbc-sbe-sdp-match-tbl)# exit

host1/Admin(config-sbc-sbe)# sdp-policy-table policytab1

host1/Admin(config-sbc-sbe-sdp-policy-tbl)# match-table matchtab1

host1/Admin(config-sbc-sbe-sdp-policy-tbl)# exit

host1/Admin(config-sbc-sbe)# sdp-policy-table policytab2

host1/Admin(config-sbc-sbe-sdp-policy-tbl)# match-table matchtab2

host1/Admin(config-sbc-sbe-sdp-policy-tbl)# exit

host1/Admin(config-sbc-sbe)# cac-policy-set 1

host1/Admin(config-sbc-sbe-cacpolicy)# first-cac-table 1

host1/Admin(config-sbc-sbe-cacpolicy)# first-cac-scope global

host1/Admin(config-sbc-sbe-cacpolicy)# cac-table 1

host1/Admin(config-sbc-sbe-cacpolicy-cactable)# match-type src-adjacency 

host1/Admin(config-sbc-sbe-cacpolicy-cactable)# entry 1

host1/Admin(config-sbc-sbe-cacpolicy-cactable-entry)# match-value sipp1

host1/Admin(config-sbc-sbe-cacpolicy-cactable-entry)# action cac-complete  

host1/Admin(config-sbc-sbe-cacpolicy-cactable-entry)# caller-inbound-policy policytab1

host1/Admin(config-sbc-sbe-cacpolicy-cactable-entry)# caller-outbound-policy policytab1

host1/Admin(config-sbc-sbe-cacpolicy-cactable-entry)# callee-inbound-policy policytab2

host1/Admin(config-sbc-sbe-cacpolicy-cactable-entry)# callee-outbound-policy policytab2

host1/Admin(config-sbc-sbe-cacpolicy-cactable-entry)# exit

host1/Admin(config-sbc-sbe-cacpolicy-cactable)# exit

host1/Admin(config-sbc-sbe-cacpolicy)# complete 

host1/Admin(config-sbc-sbe-cacpolicy)# exit

host1/Admin(config-sbc-sbe)# active-cac-policy-set 1

This section provides a sample configuration and output for SIP SDP Attribute Passthrough.

host1/Admin(config-sbc-sbe)# do show services sbc interwork sbe cac-policy-set 1 table 1 
entry 1

SBC Service "interwork"

Policy set 1 table 1 entry 1

  Match value               sipp1

  Action                    CAC policy complete

  Max calls                 Unlimited

  Max call rate             Unlimited

  Max in-call rate          Unlimited

  Max out-call rate         Unlimited

  Max registrations         Unlimited

  Max reg. rate             Unlimited

  Max bandwidth             Unlimited

  Max channels              Unlimited

  Transcoder                Allowed

  Caller privacy setting    Never hide

  Callee privacy setting    Never hide

  Early media               Allowed

  Early media direction     Both

  Early media timeout       0

  Restrict codecs to list   default

  Restrict caller codecs to list   default

  Restrict callee codecs to list   default

  Media bypass              Allowed

  SRTP Transport            Not Set

  Callee hold setting       Standard

  Caller hold setting       Standard

  Number of calls rejected by this entry    0

  Caller inbound SDP policy                 policytab1

  Caller outbound SDP policy                policytab1

  Callee inbound SDP policy                 policytab2

  Callee outbound SDP policy                policytab2