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Cisco 1751 Voice-over-IP Quick Start Guide
78-11259-05
Configuring Voice-over-IP
Configuring Multilink PPP Interleaving
To configure multilink PPP and interleaving on a dialer, ISDN PRI or ISDN BRI interface, or a virtual
template, you must first configure multilink PPP and interleaving on the interface or template by entering
the following commands in interface configuration mode:
Router(config-if)#
encapsulation
ppp
Router(config-if)#
ppp multilink
Router(config-if)#
ppp multilink interleave
Optionally, configure a maximum fragment delay:
Router(config-if)#
ppp multilink fragment-delay
milliseconds
You can also reserve a special queue for real-time packet flows to specified destination User Datagram
Protocol (UDP) ports, allowing real-time traffic to have higher priority than other flows. You need the
following command only if you have not configured RSVP:
Router(config-if)#
ip rtp reserve
lowest-UDP-port range-of-ports
For virtual templates only, apply the virtual template to the multilink bundle:
Router(config-if)#
multilink virtual-template 1
To create a virtual template interface, enter the following
interface virtual-template
global
configuration command:
Router(config)#
interface
virtual-template 1
RTP Header Compression
RTP header compression on a PPP, HDLC, or similar serial interface compresses the packet header to
reduce network overhead.
You should configure RTP header compression on a serial interface if you have either of the following:
•
Links slower than 2 Mbps
•
Need to save bandwidth
Note
Do not use RTP header compression on links faster than 2 Mbps.
Configuring RTP Header Compression
Enable RTP header compression at both ends of the serial link by entering the following
ip rtp
header-compression
interface configuration command:
Router(config-if)#
ip rtp header-compression
Note
When you enter the
show running-config
command, the format of the
ip rtp header-compression
command will change to
ip rtp header-compression iphc-format
.
