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Page 88 - Part 1 IP Connectivity How Do I?
QoS over WAN between IPNC & 3rd Party Router
IPNC QoS is fully compliant with 3rd party router manufacturers that support Link
fragmentation using PPP Multilink and IP Header compression (IPHC) (RFC
2507 and RFC 2508). This interoperation applies to both point to point and Frame
Relay links using PPP encapsulation (see page 83).
All vendors that support a QoS mechanism on their routers will present their own
method of voice traffic prioritisation to slow speed WAN links. The operation of
such QoS mechanisms is “local” to a system but require that the enabling PPP
protocols be negotiated on the link. IPNC will interoperate with any vendors QoS
as long as the “enabling protocols” are agreed on the established link.
The “enabling protocols” for low speed WAN links are the PPP options for IP
Header Compression (RFC 2508) and PPP Multilink (RFC1990). As long as
these options are agreed on the PPP link (see The PPP Tab on page 52) then
each router will “locally” apply QoS to their respective end of the link.
3rd party router interoperation relies on the successful negotiation of PPP
protocol options (IPHC and Multilink). Once the PPP protocol options are agreed
on the link both routers are then able to apply QoS polices to their respective
ends of the link using fragmentation interleave and IP Header compression.
Extns 1A & 1B Extns 2A & 2B
192.168.123.101/24
192.168.123.1/24
PPP Link (128k)
192.168.42.1/24
FTP Server
IP Phone_1C
IP Phone_2C
INDeX 1
V
PN
Router#1
To configure QoS on an IPNC there are four mandatory parameters as shown
below:
1. IP Header Compression set on the Service.
2. Multilink set on the service.
3. The WAN link configured for the WAN port speed.
4. An appropriate DSCP value system/gatekeeper tab
The IPNC 3.2 software has the following operating characteristics with respects
to VoIP.
Description
Value
Voice UDP port numbers range OxC000 to 0xCFFF
Signalling TCP port number 1720
DSCP (TOS/Diffserv) value 0xA0
The Configuration of the IPNC is dependant on the 3
rd
party router functionality.
Use the quick WAN example as the basis for the configuration of interoperation
and use the IPNC Monitor application to debug the PPP protocol exchange.
Page 88 - How Do I? INDeX IPNC Cassette Administration Manual
Part 1 IP Connectivity 38DHB0002UKDD – Issue 7 (22/11/02)