User`s guide

XSR User’s Guide 107
Chapter 6 PPP Features
Configuring PPP
It also defines a new packet called Change Password Packet, which enables a
client to send a response packet based on a new password. An 8-octet
challenge string is generated using a random number generator. A change
password packet is sent in response to a failure packet from the peer that
contains the failure code for change password.
Currently, MS-CHAP authenticators do not send the name value field in the
challenge packet but construct the response packet with the first MS-CHAP
name/secret pair retrieved from the secret list. When MS-CHAP secrets are
not configured, a configure NAK will be sent with either CHAP (MD5) or
PAP protocol in response to a MS-CHAP Authentication protocol option in
the LCP request from the Windows system.
Link Quality Monitoring (LQM)
As referenced in RFC-1989, LQM defines a protocol for generating Link-
Quality-Reports. These Report packets provide a mechanism to determine
link quality, but it is up to each implementation to decide when the link is
usable. LQM carefully defines the Link-Quality-Report packet format and
specifies reference points to measure all data transmission and reception.
LQM’s functionality includes:
 Maintaining LQM statistics and sending them to the peer periodically
 Determining link quality based on statistics received from the peer
 Suspending traffic over the link, if that link quality is bad
 Monitoring suspended link quality by swapping LQM packets with peer
 Restoring the link after quality reaches a desired level (set by
configuration)
Multilink PPP (MLPPP)
Multilink PPP (MLPPP), as referenced in RFC-1990, aggregates multiple
point-to-point links to form a group with higher bandwidth. Multilink is
based on an LCP option negotiation that permits the XSR to indicate to its
peer that it is capable of combining multiple physical links into a bundle.
LCP negotiation indicates the following:
 The XSR can combine multiple physical links into one logical link