Applications; Separate Routing Of Voice And Data Traffic - Avaya G250 Administration

Configuring policy-based routing
Policy-based routing only operates on routed packets. Packets traveling within the same subnet
are not routed, and are therefore not affected by policy-based routing.
The Loopback interface is a logical interface which handles traffic that is sent to and from the
G250/G350 itself. This includes ping packets to or from the G250/G350, as well as telnet, FTP,
DHCP Relay, TFTP, HTTP, NTP, SNMP, H.248, and other types of traffic. The Loopback
interface is also used for traffic to and from analog and DCP phones connected to the device via
IP phone entities.
The Loopback interface is always up. You should attach a PBR list to the Loopback interface if
you want to route specific packets generated by the G250/G350 to a specific next-hop.
Unlike the case with other interfaces, PBR lists on the Loopback interface are applied to
packets when they leave the G250/G350, rather than when they enter.
Certain types of packets are not considered router packets (on the Loopback interface only),
and are therefore not affected by policy-based routing. These include RIP, OSPF, VRRP, GRE,
and keepalive packets. On the other hand, packets using SNMP, Telnet, Bootp, ICMP, FTP,
SCP, TFTP, HTTP, NTP, and H.248 protocols are considered routed packets, and are therefore
affected by policy-based routing on the Loopback interface.

Applications

The most common application for policy-based routing is to provide for separate routing of voice
and data traffic. It can also be used as a means to provide backup routes for defined traffic
types.

Separate routing of voice and data traffic

Although there are many possible applications for policy-based routing, the most common
application is to create separate routing for voice and data traffic.
For example, the application shown in
By DSCP on page 467 uses the DSCP field to identify VoIP control packets (DSCP=34, 41),
VoIP Bearer RESV packets (DSCP = 43, 44), and VoIP Bearer packets (DSCP = 46).
Policy-based routing sends these packets over the T1 WAN line, and sends other packets over
the Internet. This saves bandwidth on the more expensive serial interface.
466 Administration for the Avaya G250 and Avaya G350 Media Gateways
Figure 49: Policy-based routing — Voice/Data Division