Ppp And Routing Tables - Cayman Systems 2E-H User Manual

PPP and Routing
Tables
How Your Cayman 2E-H Works
C-10
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.
Your Cayman 2E-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
network. When the router receives a packet, it consults its routing
table to decide where to send the packet.
Static and Dynamic Routes
Routes to other networks can be entered and maintained manually
(static routes) or acquired from other routers interactively (dynamic
routes):
Static routes identify pathways to destination networks that are
stable over time or to networks that must always be available,
even if a link is not currently open. These static routes let each
router recognize how to reach the other, even if one router
hasn't heard from the other recently. Static routes are usually
required for a PPP link to be established "on demand," since,
without it, the router does not know which interface to route a
packet over to reach the remote network.
Dynamic routes identify pathways to destination networks that
may change over time. Dynamic routes are created and
configured when routers broadcast RIP (Routing Information
Protocol) packets advertising the networks they can reach and
the distance (number of routers) to each network.
Selecting the Most Efficient Route
The efficiency of a route is expressed in terms of the route's metric,
or hop count, which measures the number of routers a packet must
pass through to reach its destination. A route to a network connected
Cayman 2E-H User's Guide
November 2000