Lesson 6: WAN Basics

WAN Basics | Transmission Options | WAN Requirements & Solutions

  - 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.

- 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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