requirement
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... internet grows, both in size and in the diversity of
routing requirements, providing inter-domain routing that can
accommodate both of these factors becomes more and more crucial. The
...
... accommodate both of these factors becomes more and more crucial. The
number and diversity of routing requirements is increasing due to:
(a) transit restrictions imposed by source, destination, and transit
...
... networks, it does not provide support for specialized
routing requirements as flexibly and efficiently as IDPR-style
routing ...
... time providing efficient support for specialized routing
requirements.
...
... architecture does assume that routing
requirements will be diverse and that special routes will be needed.
On the other hand, the architecture does not depend on assumptions
...
... routing architecture
can support unconstrained proliferation of user requirements and
network services. At the same time, this is not necessarily a
...
... problem. The capabilities of the architecture may in fact exceed the
requirements of the users. Moreover, some of the requirements that
we regard as infeasible from the inter-domain routing ...
... architecture may in fact exceed the
requirements of the users. Moreover, some of the requirements that
we regard as infeasible from the inter-domain routing point of view,
...
...
The remainder of this report is organized as follows. Section 2
outlines the requirements and priorities that guide the design of the
NR ...
... NR and SDR components. Sections 3 and 4 describe the NR and SDR
design choices, respectively, in light of these requirements.
Section 5 describes protocol support for the unified architecture and
...
... Architectural Requirements and Priorities ...
... priorities. This section defines complexity, abstraction, policy,
and type of service requirements.
...
... of domains in an internet. To satisfy this requirement with respect
to the RIB, the architecture ...
... routing and forwarding information, or
retrieval of a subset of this information on demand. To satisfy this
requirement with respect to the FIB, the architecture must provide
...
... The SDR component will use on-demand computation and caching.
Therefore the complexity of this computation can be somewhat higher.
Another reason for relaxed complexity requirements for SDR is that
SDR is expected to compute routes to a smaller number of destinations
...
... At the same time, since preserving each domain's independence and
autonomy is one of the crucial requirements of inter-domain routing,
the architecture ...
... routes must be comparable with that of NR routes, and should
always be bound by the complexity requirements outlined earlier
[Foonote: As discussed earlier, theoretically the state overhead ...
... types of traffic uniformly. To support diverse traffic requirements
in a heterogeneous environment, various resource management
...
...
Beyond this requirement, most of the proposals for extending the IP
address space, for example, can be used in conjunction with our
...
... addresses the design choices made for the NR component
in light of the above architectural requirements and priorities. All
of our discussion ...
... scalability (with respect to
the size of the internet) is one of the fundamental requirements for
the NR component, it must provide multiple mechanisms with various
...
... NR component is optimized to satisfy the common case
routing requirements for an extremely large population of users, this
does not imply that routes produced by the NR component would not be
...
... all
domains to have exactly the same information; this clearly
contradicts the notion of selective information hiding. That is, the
requirement to perform selective information hiding is unsatisfiable
with LS hop-by-hop routing ...
...
In addition, consistency requirements (essential for NR) are
unnecessary for the SDR component. Therefore LS information for
...
... algorithms does not preclude common handling of packet
forwarding. Even if LS were used for NR, the requirement would
be the same, i.e., that the forwarding agent can determine
...
... intermediate nodes with the task of looking for and selecting a route
with the specialized requirements. In addition, if the demand for
the route is unpredictable, and thus can be determined only by the
...
... routing is to compute a route that satisfies a set of specialized
requirements, and these requirements take precedence over optimality.
In other words, even if a routing ...
... route that satisfies a set of specialized
requirements, and these requirements take precedence over optimality.
In other words, even if a routing domain ...
... NR has sufficient information to compute a route, given a particular
set of requirements, the architecture does not guarantee that the
computed route ...
...
Note that the above requirement does not imply that only a few
domains can participate in SDR, or that routes installed by the SDR
...
... domains can participate in SDR, or that routes installed by the SDR
component must have short life times. What the requirement does
imply, is that the product of the number of routes specified by
domains ...
... important) to the SDR component. Instead, the primary focus of the
SDR component is shifted towards the ability to compute routes that
satisfy specialized requirements, where we assume that the total
number of domains requiring special routes simultaneously through the
...
... Little, M., "Goals and Functional Requirements for Inter-Autonomous System Routing", RFC 1126 ...