Chapter 2: About the HSIM-W6
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HSIM-W6 Installation Guide
In half-duplex operation, the authenticator device challenges the peer device by generating a
CHAP challenge, and the challenge contains an MD5 algorithm with a random number that has
the encrypted password and system name. The peer device then applies a one-way hash algorithm
to the random number and returns this encrypted information along with the system name in the
CHAP response. The authenticator then runs the same algorithm and compares the result with the
expected value. This authentication method depends upon a password or secret, known only to
both ends locally.
Full-duplex operation places an additional step to the half-duplex operation that mirrors the
operation discussed above for a peer to validate the authenticator. The peer device challenges the
authenticator by generating a CHAP challenge, and the authenticator returns a CHAP response.
The peer device challenges the authenticator device by generating a CHAP challenge, and the
challenge contains an MD5 algorithm with a random number that has the encrypted password and
system name. The authenticator device then applies a one-way hash algorithm to the random
number and returns this encrypted information along with the system name in the CHAP response.
The peer device then runs the same algorithm and compares the result with the expected value.
This authentication method depends upon a password or secret, known only to both ends locally.
LQM
Link Quality Monitoring (LQM) is a link control mechanism used with PPP to determine when
and how often a link is dropping data in units of packets and octets. Link Quality Monitoring
accomplishes this by providing Link-Quality-Reports to determine if the quality of the link is
adequate for operation. Link Quality Monitoring provides separate measurements for both
incoming and outgoing packets that are communicated to both ends of the link. The PPP LQM
mechanism carefully defines the Link-Quality-Report packet formats, and specifies reference
points for all data transmission and reception measurements. The LQM implementation maintains
successfully received packet and octet counts, and periodically transmits this information to its
peer using Link-Quality-Report packets.
Multilink Protocol
Multilink Protocol (MP) is an extension of PPP that controls the way frames are transferred across
several links whenever a single link cannot handle the present traffic load. Multilink Protocol
establishes several simultaneous links between two end points over switched circuits (dial-up
lines) in an ISDN network, and dynamically adjusts the bandwidth demands between available
links to maintain an effective data transfer.
