routing
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... IP
connectivity is realized via Internet-wide distributed routing, which
involves multiple providers, and thus implies certain degree of
cooperation and coordination. Therefore, there is a need to balance
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... Routing Requirements ...
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Conceptually routing requirements can be classified into the
following three categories: source preferences, destination ...
... destinations.
In view of a potentially wide variety of routing requirements, we
need to get a better understanding on the relative practical
...
... need to get a better understanding on the relative practical
importance of various routing requirements. In practice organizations
usually don't formulate their routing ...
... routing requirements. In practice organizations
usually don't formulate their routing requirements in a vacuum. For
example, since the primary role ...
... to a set of subscribers, the provider usually formulates its routing
requirements based on the set of the routing ...
... provider is expected to serve.
Support for various routing requirements should take into account the
overhead ...
... requirements. A situation where an organization can unilaterally
impose routing information overhead on other organization (e.g., by
requiring the other organization to maintain an additional routing
information ...
... requiring the other organization to maintain an additional routing
information) should be viewed as undesirable. The cost of supporting
a particular routing requirement should not be borne by organizations
that do not benefit from supporting that requirement ...
... that do not benefit from supporting that requirement. Ideally the
routing system should allow to shift the overhead associated with a
particular routing ...
... routing system should allow to shift the overhead associated with a
particular routing requirement towards the entity that instigates the
...
... header compression vs carrying explicit forwarding information on a
per packet basis). Organizations with simple routing requirements
shouldn't bear the same routing information ...
... routing requirements
shouldn't bear the same routing information overhead as organizations
with complex routing ...
... A situation where the overhead associated with supporting a
particular routing requirement has to be carried by every entity
...
... the requirement could be viewed as undesirable. An organization
should be able to instantiate its routing requirements in a more or
less central fashion, for example by utilizing just some of the
...
... routers.
Even if the scope of the routing information overhead is purely
local, there is a need to perform a careful analysis of the tradeoff
...
... local, there is a need to perform a careful analysis of the tradeoff
between the potential benefits and the cost associated with
supporting various routing requirements.
...
... existing IP infrastructure. This has certain
implications for the Internet routing system.
In the presence of encapsulation ...
... created via encapsulation on the semantics of routing
requirements, as well as the interaction among the routing ...
... routing
requirements, as well as the interaction among the routing
requirements by the entities that form the overlay and the entities
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... Price Structure and its Impact on Routing ...
...
Routing among providers, as well as between providers and subscribers
may be influenced by the price structure employed by the providers,
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... subscribers. A provider can view
routing as a mechanism that allows the provider to exert control over
who can use the provider ...
... provider's services. A subscriber can view routing as
a mechanism that allows the subscriber to exert control over the
...
...
The need to exert control has to be carefully balanced against the
cost of the routing mechanisms needed to provide such control. In a
competitive market one could question the viability of a mechanism
whose incremental cost would be greater than the saving recovered by
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... One of the key requirements imposed on the Internet routing is its
ability to scale. In addition to conventional metrics for scalability
...
...
Scaling implies that the Internet routing system needs to have
powerful mechanisms to provide routing information
...
... Internet routing system needs to have
powerful mechanisms to provide routing information
aggregation/abstraction.
...
... should allow a provider to control the amount of its local resources
needed to deal with the routing overhead based on considerations that
are purely local to the provider ...
... provider.
One of the side effects of the routing information
aggregation/abstraction is that some of the routing information ...
... routing information
aggregation/abstraction is that some of the routing information is
going to be lost. This may impact route optimality and even the
...
... route optimality and even the
ability to find an existing route. The need for routing information
aggregation/abstraction also implies certain homogeneity of the
...
... information to be aggregated/abstracted. This needs to be counter-
balanced against the potential diversity of routing requirements.
...
... requirements.
As a way to deal with the routing information loss due to
aggregation/abstraction, we need to explore mechanisms that allow
...
... aggregation/abstraction, we need to explore mechanisms that allow
routing that is based on the on-demand acquisition of subsets of
unaggregated information.
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...
The overhead associated with supporting specific routing requirements
has a direct impact on the overall scalability ...
... scalability of the Internet
routing system. We need to get a better understanding of how various
routing requirements ...
... routing system. We need to get a better understanding of how various
routing requirements impact scalability. When the impact is
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... Hierarchical Routing ...
... 1519(-> 4632)) that is used
today for scalable Internet-wide routing is based on the technique of
hierarchical routing. Essential to this technique is the assumption
...
... Internet-wide routing is based on the technique of
hierarchical routing. Essential to this technique is the assumption
that Network layer ...
... addresses.
One of the fundamental consequences of using hierarchical routing is
that in order to preserve topological significance of network
...
...
Multi-level hierarchical routing allows for recapturing additional
routing information (routing ...
... Multi-level hierarchical routing allows for recapturing additional
routing information (routing entropy) due to the mismatch between
...
... hierarchical routing allows for recapturing additional
routing information (routing entropy) due to the mismatch between
addresses ...
... addresses and topology at a particular level in the routing hierarchy
at some higher level in the hierarchy (e.g., at an exchange point
among providers). This enables the routing system ...
... routing hierarchy
at some higher level in the hierarchy (e.g., at an exchange point
among providers). This enables the routing system to contain the
scope of entities impacted by the mismatch. Containing the scope of
entities could be an important factor to facilitate graceful
...
... indiscriminately to all the organizations connected to the Internet
-- hierarchical routing requires that most, but not all addresses be
topologically significant. For a large organization it could be
...
... destinations within the organization can be
represented within the Internet routing system as a small number of
address prefixes, even if these address prefixes ...
... ("provider-independent" addresses). The volume of routing information
that a large organization would inject into the Internet routing
system ...
... routing information
that a large organization would inject into the Internet routing
system would be comparable to the (aggregated) routing information
associated with a large number of small organizations.
...
... that a large organization would inject into the Internet routing
system would be comparable to the (aggregated) routing information
associated with a large number of small organizations.
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... Routing Information Sharing ...
... consistency of the Internet-wide routing could significantly benefit
if the information about routing requirements ...
... Internet-wide routing could significantly benefit
if the information about routing requirements of various
organizations could be shared across organizational boundaries. Such
...
... organizations could be shared across organizational boundaries. Such
information could be used in a wide variety of situations ranging
from troubleshooting to detecting and eliminating conflicting routing
requirements. The scale of the Internet ...
... Internet implies that the information
should be distributed. Work is currently underway to establish
depositories of this information (Routing Registries), as well as to
develop tools that analyze, as well as utilize this information.
...
... renumbering
- further work is needed to investigate feasibility of routing
information aggregation above the direct (immediate) provider
...
... - further work is needed to get a better understanding on the
relative practical importance of various routing requirements
...
... requirements
- further work is needed to understand of how various routing
requirements impact scalability ...
... requirements impact scalability of the routing system
- further work is needed to investigate alternatives to
...
...
- further work is needed to investigate alternatives to
hierarchical routing
Finally, the following tasks are viewed as long term:
...
...
- further work is needed to understand and utilize the benefits of
routing information sharing
- further work is needed to understand the implications of virtual
...
...
- further work is needed to understand how different price
structures influence routing requirements
...
... multi-provider Internet. There are no doubt routing-related areas
that are not covered in this document. For instance, such areas as
multicast routing ...
... routing-related areas
that are not covered in this document. For instance, such areas as
multicast routing, or routing in the presence of mobile hosts, or
...
... that are not covered in this document. For instance, such areas as
multicast routing, or routing in the presence of mobile hosts, or
routing ...
... routing in the presence of mobile hosts, or
routing in the presence of a large shared media (e.g., ATM) aren't
discussed here. Further work is needed to understand the implications
...
... The impact of multi-provider Internet goes well beyond just routing,
and percolates into such areas as network management,
...