WAN Basics
- Snapshot Routing
By default, routing protocols such as RIP
exchange routing tables every 30 seconds. If placed as calls,
these routine updates will drive up WAN costs unnecessarily,
and Snapshot Routing limits these calls to the remote site.
A remote router with this feature only requests a routing
update when the WAN link is already up for the purpose of
transferring user application data.
Without Snapshot Routing, your ISDN connection would be dialed
every 30 seconds; this feature ensures that the remote router
always has the most up-to-date routing information but only
when needed.
- IPX Protocol Spoofing
Protocol spoofing allows the user to improve
performance while providing the ability to use lower line
speeds over the WAN.
- Compression
Compression reduces the space required to
store data, thus reducing the bandwidth required to transmit.
The benefit of these compression algorithms is that users
can utilize lower line speeds if needed to save costs. Compression
also provides the ability to move more data over a link than
it would normally bear.
- Three types
Header
Link
Payload
- Van Jacobson header compression
RFC 1144
Reduces header from 40 to ~5
bytes
- Dial Backup
Dial backup addresses a customer’s need for reliability
and guaranteed uptime. Dial backup capability offers users protection against
WAN downtime by allowing them to configure a backup serial line via a circuit-switched
connection such as ISDN. When the software detects the loss of a signal from the
primary line device or finds that the line protocol is down, it activates the
secondary line to establish a new session and continue the job of transmitting
traffic over the backup line.
Related Topics
- Summary -
- The network operates beyond the local
LAN’s geographic scope. It uses the services of carriers
like regional bell operating companies (RBOCs),
Sprint, and MCI.
- WANs use serial connections of various types to access
bandwidth over wide-area geographies.
- An enterprise pays the carrier or service provider for connections used
in the WAN; the enterprise can choose which services it uses;
carriers are usually regulated by tariffs.
- WANs rarely shut down, but since the enterprise must
pay for services used, it might restrict access to connected
workstations. All WAN services are not available in all locations.
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