Cisco Cisco IOS Software Release 12.4(15)T

Typically, service providers use a VRF between PE and CE routers to provide VPN support for 
customers. VRF is also used to segment data and voice traffic for improved traffic management, and VRF 
can be configured on an interface to process incoming packets according to the assigned VRF. 

By configuring VRF-awareness on voice gateways you can specify a VRF for the voice traffic that is 
generated from within the gateway. The voice VRF is added to the VoIP service provider interface (SPI) 
of the gateway to send and receive signaling and media packets in the configured VRF. The SPI can send 
signaling and media packets only in the configured VRF, and receive signaling and media packets only 
from the configured VRF. 

To configure a voice VRF, you must shut down voice services on the gateway, assign a previously defined 
VPN VRF to the VoIP SPI, and then restart voice services.

This section describes the tasks required to configure VRF-aware H.323 and SIP for voice gateways.

If a voice VRF is not configured, signaling and media packets are sent using the default routing table.

Be sure to check the following prerequisites before configuring a voice VRF:

To ensure there are no active calls on the voice gateway during a VRF change, you must shut down 
the voice gateway before you configure or make changes to a voice VRF.

If your configuration uses address binding, use the h323-gateway voip bind srcaddr ip-address 
command to bind the gateway to an interface that belongs to the voice VRF.

If the voice gateway configuration has H.323 RAS enabled, use the h323-gateway voip interface 
command to configure RAS on the interface that belongs to the voice VRF.

Restrictions for configuring VRF-aware H.323 and SIP are as follows:

If the voice gateway configuration has H.323 RAS enabled, the gatekeeper must be accessible to the 
gateway in the configured voice VRF.

When voice VRF is configured, the H.323 gateway and gatekeeper cannot communicate with each 
other if they are running on same router.

Voice VRF supports only the following call types:

A single VRF for SIP-to-SIP calls

A single VRF for H323-to-SIP calls

A single VRF for H323-to-H323 calls

A single VRF in IP-to-IP gateway call with a gatekeeper involved, but the gatekeeper is not on the 
same router.

A SIP SRST call