User Guide

Chapter 1. Advanced Topics 11
Chapter 1. Advanced Topics
This chapter provides information on advanced topics useful to network administrators.
Interoperability
The router uses industry-wide standards to ensure compatibility with routers and equipment from other vendors.
To interoperate, the router supports standard protocols on the physical level, data link level for frame type or
encapsulation method, and network level. For two systems to communicate directly, they must use the same
protocol at each level. Most protocols do not support negotiable options, except for PPP.
The physical protocol level includes hardware and electrical signaling characteristics. This support is provided by
the router Ethernet and modem hardware interfaces.
The data-link protocol level defines the transmission of data packets between two systems over the LAN or WAN
physical link.
The frame type or encapsulation method defines a way to run multiple network-level protocols over a single LAN
or WAN link. The router supports the following WAN encapsulations:
• PPP (VC multiplexing)
• PPP (LLC multiplexing)
• RFC 1483 (for ATM)
• RFC 1483 with MAC encapsulated routing (for ATM)
• FRF8 (for ATM)
• RFC 1490 (for Frame Relay)
• RFC 1490 with MAC encapsulated routing (for Frame Relay)
Routing
The network protocol provides a way to route user data from source to destination over different LAN and WAN
links. Routing relies on routing address tables to determine the best path for each packet to take.
The routing tables can be seeded; i.e., addresses for remote destinations are placed in the table along with path
details and the associated costs (path latency).
The routing tables are also built dynamically; i.e., the location of remote stations, hosts, and networks are updated
from broadcast packet information.
Routing helps to increase network capacity by localizing traffic on LAN segments. It also provides security by
isolating traffic on segmented LANs. Routing extends the reach of networks beyond the limits of each LAN
segment.
Numerous network protocols have evolved, and within each protocol are associated protocols for routing, error
handling, network management, etc. The following chart displays the networking and associated protocols
supported by the router.