RFC 2105 (rfc2105) - Page 2 of 13
Cisco Systems' Tag Switching Architecture Overview
Alternative Format: Original Text Document
RFC 2105 Cisco's Tag Switching Architecture February 1997
4.4 Flexible routing (explicit routes) ..................... 9
5 Tag switching with ATM ................................. 9
6 Quality of service ..................................... 11
7 Tag switching migration strategies ..................... 11
8 Summary ................................................ 12
9 Security Considerations ................................ 12
10 Intellectual Property Considerations ................... 12
11 Acknowledgments ........................................ 12
12 Authors' Addresses ..................................... 13
1. Introduction
Continuous growth of the Internet demands higher bandwidth within the
Internet Service Providers (ISPs). However, growth of the Internet is
not the only driving factor for higher bandwidth - demand for higher
bandwidth also comes from emerging multimedia applications. Demand
for higher bandwidth, in turn, requires higher forwarding performance
(packets per second) by routers, for both multicast and unicast
traffic.
The growth of the Internet also demands improved scaling properties
of the Internet routing system. The ability to contain the volume of
routing information maintained by individual routers and the ability
to build a hierarchy of routing knowledge are essential to support a
high quality, scalable routing system.
We see the need to improve forwarding performance while at the same
time adding routing functionality to support multicast, allowing more
flexible control over how traffic is routed, and providing the
ability to build a hierarchy of routing knowledge. Moreover, it
becomes more and more crucial to have a routing system that can
support graceful evolution to accommodate new and emerging
requirements.
Tag switching is a technology that provides an efficient solution to
these challenges. Tag switching blends the flexibility and rich
functionality provided by Network Layer routing with the simplicity
provided by the label swapping forwarding paradigm. The simplicity
of the tag switching forwarding paradigm (label swapping) enables
improved forwarding performance, while maintaining competitive
price/performance. By associating a wide range of forwarding
granularities with a tag, the same forwarding paradigm can be used to
support a wide variety of routing functions, such as destination-
based routing, multicast, hierarchy of routing knowledge, and
flexible routing control. Finally, a combination of simple
forwarding, a wide range of forwarding granularities, and the ability
to evolve routing functionality while preserving the same forwarding
paradigm enables a routing system that can gracefully evolve to
Rekhter, et. al. Informational