Table Of Contents

IBCF Processing Support

Contents

Restrictions for Implementing IBCF Support

Information About IBCF Support

Adding to Path Header on REGISTER

Modifying Service-Route Header on REGISTER

Routing based on SIP Route headers

Topology Hiding

Screening of SIP Signaling

Passthrough of From, To, and Contact Headers

Passthrough of Request URI on REGISTER

Interworking with P-CSCF, I-CSCF, and S-CSCF

Handling Messages from Untrusted Domains

Implementing IBCF Support

Configuring the Domain Names to Use for IBCF Adjacencies

Additional References

Related Documents

Standards

MIBs

Technical Assistance

IBCF Processing Support

---

Users can configure the SBC to perform the role of an Interconnection Border Control Function (IBCF) SIP border gateway, both managing requests across a network border between IMS core networks and interworking with non-IMS core networks, such as H.323 networks.

When functioning as an IBCF, the SBC supports the following IBCF functions:

•Adding to Path header on REGISTER

•Modifying Service Route header

•Routing based on SIP Route headers

•Topology hiding

•Screening of SIP signaling

•Passthrough of From, To, and Contact headers

•Passthrough of request URI on REGISTER

•Interworking with P-CSCF, I-CSCF, and S-CSCF

•Handling messages from untrusted domains

Feature History for IBCF Support

Release	Modification
Release 3.5.1	This feature was introduced on Cisco XR 12000 Series Router.
Release 3.6.0	No modification.

Contents

This module contains the following sections:

•Restrictions for Implementing IBCF Support

•Information About IBCF Support

•Implementing IBCF Support

•Additional References

Restrictions for Implementing IBCF Support

The following features are not included in the SBC IBCF support:

•Blacklist or whitelist header-values-content-type, content-disposition, and content-language headers

•Blacklist or whitelist MIME bodies

•Session timer

•Co-location with I-CSCF

•SBC does not reject long message bodies.

•SBC does not check the length of SIP bodies.

•SBC does not provide a default implementation of the Encryption User Exit.

•SBC does not hide network devices that are identified by IP addresses.

•SBC does not support the full IBCF handling of failed REGISTERs.

•SBC does not provide interoperability between IMS and other SIP domains.

•The IBCF selection of a new entry point for forwarding REGISTER requests is limited to SIP Server Location procedures (per RFC 3263) and is applicable only if the initial server selected does not respond.

Information About IBCF Support

Adding to Path Header on REGISTER

When the SBC is configured to perform the role of an IBCF gateway, the IBCF adds itself to the Path header to ensure that all INVITE requests to the subscriber are routed via the IBCF.

Modifying Service-Route Header on REGISTER

The Service-Route header is analogous to the Path header, but it is used to specify the list of devices a call should traverse for calls originating from a subscriber. By default, the IBCF does not modify the Service-Route header sent on REGISTER responses. However, if topology hiding is required, then the IBCF encrypts the header elements that match its configured HomeNetworkId.

Routing based on SIP Route headers

You can configure the SBC to route Dialog-creating requests, such as INVITE, to the next hop-IP address based on the Route header, which ensures that the SIP messages go through the specified border gateways between networks and the S-CSCF that handled the UA's REGISTER.

Topology Hiding

The SBC hides those parts of the routing-related headers which reveal the internal topology of the SBC network. But this feature also ensures that the headers are usable for INVITE requests and other methods.

Screening of SIP Signaling

When configured to perform the role of an IBCF gateway, the SBC does not screen certain SIP headers using profile whitelists and blacklists.

Passthrough of From, To, and Contact Headers

For Dialog-creating and Out-of-dialog requests, the SBC allows the From, To, and Contact header URIs to pass through without modifying them. For dialog headers, the SBC uses the values corresponding to those on the Out-of-dialog requests.

Passthrough of Request URI on REGISTER

The SBC allows the Request URI on a REGISTER message to pass through with modifying it.

Interworking with P-CSCF, I-CSCF, and S-CSCF

When performing the role of an IBCF gateway, the SBC allows the CSCF-specific headers on SIP messages to pass through.

Handling Messages from Untrusted Domains

When the SBC is acting as an IBCF entry point, it handles out-of-dialog requests from untrusted domains as follows:

•The SBC rejects all REGISTER requests with a 403 response.

•The SBC removes all P-Asserted-Identity headers, P-Access-Network-Info headers, P-Charging-Vector headers, and P-Charging-Function-Address headers from other requests.

•The SBC rejects requests if the router contains the Orig parameter.

Implementing IBCF Support

Configuring the Domain Names to Use for IBCF Adjacencies

SUMMARY STEPS

1. configure

2. sbc service-name

3. sbe

4. sip home network identifier domain-name

5. sip encryption key string

6. adjacency sip adjacency-name

7. home network identifier domain-name

8. encryption key string

9. commit

10. exit

DETAILED STEPS

	Command or Action	Purpose
Step 1	configure Example: RP/0/0/CPU0:router# configure	Enables global configuration mode.
Step 2	sbc service-name Example: RP/0/0/CPU0:router(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: RP/0/0/CPU0:router(config-sbc)# sbe	Enters the mode of a SBE entity within an SBC service.
Step 4	sip home network identifier domain name Example: RP/0/0/CPU0:router(config-sbc-sbe)# sip home network identifier mydomain.com	Configures the specified domain name as the global home network identifier for use in all SIP IBCF adjacencies. Use the domain-name argument to specify the domain name of the SIP adjacency.
Step 5	sip encryption key string Example: RP/0/0/CPU0:router(config-sbc-sbe)# encryption key code1	Configures a global encryption key for all SIP IBCF adjacencies. •Use the string value to specify the encryption key to use for all SIP IBCF adjacencies.
Step 6	adjacency sip adjacency name Example: RP/0/0/CPU0:router(config-sbc-sbe)# sip adjacency sip sipadj	Enters the mode of an SBE SIP adjacency. •Use the adjacency-name argument to define the name of the SIP adjacency.
Step 7	home network identifier network name Example: RP/0/0/CPU0:router(config-sbc-sbe-adj-sip)# home network identifier Cisco.com	Configures a home network identifier on an IBCF adjacency. Use the network-name argument to specify the name of the home network identifier.
Step 8	encryption key string Example: RP/0/0/CPU0:router(config-sbc-sbe-adj-sip)# encryption key code2	Configures an encryption key on the SIP IBCF adjacency. •Use the string value to specify the encryption key for the SIP IBCF adjacency.
Step 9	commit Example: RP/0/0/CPU0:router(config-sbc-sbe-adj-sip)# commit	Saves configuration changes. Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.
Step 10	exit Example: RP/0/0/CPU0:router(config-sbc-sbe-adj-sip)# exit	Exits the SIP adjacency mode to the SBE mode.

Additional References

The following sections provide references related to IBCF support on the SBC.

Related Documents

Related Topic	Document Title
Cisco IOS XR master command reference	Cisco IOS XR Master Commands List
Cisco IOS XR SBC interface configuration commands	Cisco IOS XR Session Border Controller Command Reference
Initial system bootup and configuration information for a router using the Cisco IOS XR Software	Cisco IOS XR Getting Started Guide
Cisco IOS XR command modes	Cisco IOS XR Command Mode Reference

Standards

Standards	Title
No new or modified standards are supported by this feature, and support from existing standards has not been modified by this feature.	—

MIBs

MIBs	MIBs Link
—	To locate and download MIBs using Cisco IOS XR software, use the Cisco MIB Locator found at the following URL and choose a platform under the Cisco Access Products menu: http://cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml

Technical Assistance

Description	Link
The Cisco Technical Support website contains thousands of pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content.	http://www.cisco.com/techsupport