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An understanding of the following key
points should have been achieved:
- Routed or routable protocol
characteristics
- The steps of data encapsulation in
an internetwork as data is routed to one or more Layer 3 devices
- Connectionless and
connection-oriented delivery
- The IP packet fields
- Routers operate at the network
layer. Initially, the router receives a Layer 2 frame with a Layer 3
packet encapsulated within it. The router must strip off the Layer 2
frame and examine the Layer 3 packet. When the router is ready to
transmit the packet, the router then must encapsulate the Layer 3
packet in a new Layer 2 frame.
- Routed protocols define the format
and use of the fields within a packet. Packets generally are
conveyed from end system to end system.
- LAN switching occurs at Layer 2 of
the OSI reference model, and routing occurs at Layer 3.
- Routing protocols are used between
routers to determine paths and maintain routing tables. Routed
protocols are used to direct user traffic.
- Routing involves two basic
activities: determining the best routing paths and transporting
packets through an internetwork.
- Routing algorithms process routing
updates and populate the routing table with the best routes.
- Routing tables contain the best
routes to all known networks. These routes can be either static
routes, which are entered manually, or dynamic routes, which are
learned through routing protocols.
- Convergence describes the speed at
which all routers agree on a change in the network.
- Interior routing protocols route
data within autonomous systems, while exterior routing protocols
route data between autonomous systems.
- Routers using distance-vector
routing protocols periodically send routing updates consisting of
all or part of its routing table. Routers using link-state routing
protocols use link-state advertisements (LSAs) to send updates only
when topological changes occur in the network, and send complete
routing tables much less frequently.
- The uses for subnetting
- How to determine the appropriate
subnet mask for a given situation
- How to subnet Class A, B, and C
networks
- How to use a subnet mask to
determine the subnet ID
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