CCNP : Notes...
The primary purpose of segmentation is to reduce congestion in the
network.
4.
Bridges and switches forwards all broadcasts, which puts extra load
on the network. In other words, though bridges divide the network
into different collision domains, the broadcast domain remain only
one. This increases the overhead on the network.
5.
The Cisco IOS features that allow reduction in bandwidth are:
-
Access
Control Lists: ACLs are used to permit or deny protocol update
traffic, data traffic, and broadcast traffic. Cisco access lists
are available for IP, IPX, and AppleTalk protocols.
-
Snapshot
routing: Snapshot routing can reduce WAN costs, by exchanging
the routing table at predefined intervals. The routing tables
for the distance vector protocols are kept frozen until the next
update occurs. Snapshot routing is used only on distance vector
protocols such as IP RIP. Snapshot routing is widely used on
ISDN lines.
-
Compression
over WANs: Cisco IOS supports TCP/IP packet header, as well as
data compression. Link compression is also supported, that
compresses both header and data information in packets across
point to point connections.
-
DDR (Dial on
Demand Routing): DDR are useful when the traffic flow is not
continuous in nature. In DDR, channel is created only after
intended traffic is detected by the router, by dialing the
destination.
-
Switched
network access: Switched networks, such as Frame Relay, X.25 can
share the bandwidth by establishing virtual circuits.
-
Optimization
of routing table size: Routing table entries consume bandwidth
and processing power. These entries can be reduced by techniques
such as route summarization, and incremental updates.
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