SIP IP-FQDN URI Translation
Cisco Unified Border Element (SP Edition) supports translation between IP addresses and fully-qualified domain names (FQDNs) in the Request-URI, To header, and From header in Session Initiation Protocol (SIP) messages, permitting SBC to interconnect SIP devices, expecting specific SIP URI formats.
Note
This feature is supported in the unified model for Cisco IOS XE Release 2.5 and later.
Cisco Unified Border Element (SP Edition) was formerly known as Integrated Session Border Controller and may be commonly referred to in this document as the session border controller (SBC).
Feature History for IP to FQDN URI Translation Support
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Contents
Restrictions for SIP IP-FQDN URI Translation
The following restrictions apply when you configure the SIP IP-FQDN URI translation on the Cisco Unified Border Element (SP Edition):
- Each IP address and FQDN required for translation must be explicitly configured on Cisco Unified Border Element (SP Edition).
- Cisco Unified Border Element (SP Edition) configures only one mapping for each IP address and FQDN.
- The FQDN must be unique when a bidirection mapping is configured. SBC can configure multiple IP addresses that map to a single FQDN (IP1 -> FQDN1; IP2 -> FQDN1), but it can not configure a single FQDN to map to multiple IP addresses.
Information About SIP IP-FQDN URI Translation
URI Translation
The URIs in the Request-URI, To header, and From header are translated based on the configuration of the ingress and egress adjacency.
The domain part of the SIP or SIPs URI is converted after the translation is configured and a mapping is found in the IP-to-FQDN mapping table. If no mapping is found, the SIP request is forwarded without any modification in the domain part.
For example, the following INVITE (with only the relevant parts shown):
The reverse conversion is also possible.
The To and From headers are established at initial call setup and are not changed later. Hence, any change in the mapping table does not affect existing calls.
For outbound requests on an adjacency, translation can be configured in one direction only, such as from IP address to FQDN. The domain part of the URI is converted only if it is an IP address. If it is already an FQDN, no conversion is required. Similarly, for inbound requests on an adjacency, translation can be configured in one direction only; this would typically be the other direction from inbound requests.
To prevent DNS lookups for outgoing Request-URI, IP->FQDN translations configure “force-signaling-peer”, which enforces strict routing.
An exact case-insensitive match is required to translate an FQDN. For example, the mapping "aaa.com <-> 1.1.1.1" would not match the domain "web.aaa.com", but it would match the domain “AAA.com”.
Note If SIP to Tel URI conversion is also configured for the adjacency, this takes precedence over translation between IP address and FQDN. If the egress adjacency is configured to rewrite the To header or From header, this also takes precedence over translation between IP address and FQDN.
Configuring SIP IP-FQDN URI Translation
Cisco Unified Border Element (SP Edition) provides a configurable mapping between IP addresses and FQDNs to convert an IP address to a FQDN and a FQDN to an IP address in the Request-URI, To header, and From header. This behavior is configurable on a SIP adjacency, which can be either or both of the ingress and egress adjacency. When configured on the ingress adjacency, the translated URI is used as an input to routing, screening, data modification, CAC policy, and CDRs.
This section contains the steps to configure the SIP IP-FQDN URI Translation feature.
SUMMARY STEPS
4. adjacency sip adjacency-name
5. translate {request-uri | to | from} {inbound | outbound} {ip-fqdn | fqdn-ip}
7. sip ip-fqdn-mapping index ipv4 ip-address fqdn {both-ways | ip-to-fqdn}
DETAILED STEPS
Configuration Example for SIP IP-FQDN URI Translation
The following example shows how to configure the SIP IP-FQDN URI Translation for Cisco Unified Border Element (SP Edition):
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