User`s guide

How Your Cayman 3220-H Works Cayman 3220-H User’s Guide
C-10 December 2000
Network Configuration
After a PPP link has been established and authentication has been
satisfied, PPP sends Network Control Protocol (NCP) packets to
configure one or more network layer protocols, such as TCP/IP.
Link Up
Once a network-layer protocol is configured, the PPP link is
considered up (open), and datagrams for that protocol are
exchanged over the link. Either peer can close a network-layer
connection without interfering with other network-layer
connections or the LCP connection.
A PPP peer discards any packets received when the corresponding
NCP is not open.
Link Termination
A link can be terminated during initialization because a configuration
or authentication failure occurs. Once a PPP link is established, it
remains configured for communication unless explicit LCP or NCP
packets close the link or until some external event, such as the
expiration of an activity time or intervention by a network
administrator, occurs.
When a peer no longer needs a link, it sends a Terminate-Request
packet to the remote peer and closes any open NCP sessions. When
a peer sending a Terminate-Request receives a Terminate-Ack packet
(or after a specified number of unacknowledged Terminate-Request
packets are sent), it signals the physical layer to disconnect to
enforce the termination of the link.
PPP and Routing
Tables
Your 3220-H maintains a routing table for its IP routing service. The
routing table identifies the networks a router can reach, the interface
and gateway through which the router must forward a packet to
reach its destination, and the number of routers (metric or hop
count) through which a packet must travel to reach a remote