Nortel Networks 8000 - Manual (Page 144)

6 PPP and MP configuration
Nortel Secure Router 8000 Series
Configuration -WAN Access
6.5 Configuring PPP optional parameters
6.5.1 Establishing the configuration task
Applicable environment
• Call back
When the router works as the client port of the call back and the server allows calling
back to the user-specified number, you can configure dialing number needed to call the
router, and then the reverse charging is complemented.
• Packet header compression
The IP Header Compression (IPHC) Protocol is a host to host protocol and bears
real-time multimedia services such as video and audio. To reduce the consumption of
elective bandwidth, you can compress the TCP/IP packet header on the link.
• Interval between the negotiation timeout
During PPP negotiation, if the response from the peer is not received within this time
interval, PPP resends the former message.
• Polling interval
The link layer protocols such as PPP, FR and HDLC check whether the link works
normally using the polling timer.
If the network delay is too long or the congestion is severe, you can increase the polling
time interval properly to reduce network oscillation. When configuring the polling
interval, ensure that the configurations at both ends are the same.
• DNS server address negotiation
When other devices are connected to a router (usually, the router is connected to the PC
through dial-up) based on PPP, the peer devices directly access the network according to
the domain name. In this case, you need to configure the router to assign the DNS server
addresses for the peer device.
If a PC is connected to the router, you can use the winipcfg (windows98) or the ipconfig
/all (windows2000/windows XP) command to view the DNS server addresses that are
provided by the router.
The Nortel router can provide both the primary DNS server and subordinate DNS server
addresses for the peer device.
• Link quality parameter
The PPP link monitor is to test the PPP link quality in real time, including the PPP link
bound on the MP.
When the link quality is lower than the percent of the forbidden link quality, the link is
prohibited. When the link quality restores to the link quality percent, the link is enabled
automatically. To avoid the repeated oscillation between prohibition and restoration, a
holdoff time is needed before restarting the link.
Preconfiguration tasks
Before configuring PPP optional parameters, complete the following tasks:
• Configuring physical attributes of the interface.
• Encapsulating the interface with PPP.
• Configuring PAP or CHAP on the interface (only needed during the configuration of the
negotiation timeout interval).
6-18 Nortel Networks Inc. Issue 5.3 (30 March 2009)