Connected: An Internet Encyclopedia
E.3.2 The Variant Router Requirements Algorithm
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APPENDIX E Additional Next-Hop Selection Algorithms
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E.3 Some Route Lookup Algorithms
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E.3.2 The Variant Router Requirements Algorithm
E.3.2 The Variant Router Requirements Algorithm
Some Router Requirements Working Group members have proposed a
slight variant of the algorithm described in the Section
[5.2.4.3]. In this variant, matching the type of service
requested is considered to be more important, rather than less
important, than matching as much of the destination address as
possible. For example, this algorithm would prefer a default
route that had the correct type of service over a network route
that had the default type of service, whereas the algorithm in
[5.2.4.3] would make the opposite choice.
The steps of the algorithm are:
- Basic match
- Weak TOS
- Longest match
- Best metric
- Policy
Debate between the proponents of this algorithm and the regular
Router Requirements Algorithm suggests that each side can show
cases where its algorithm leads to simpler, more intuitive routing
than the other's algorithm does. This variant has the same set of
advantages and disadvantages that the algorithm specified in
[5.2.4.3] does, except that pruning on Weak TOS before pruning on
Longest Match makes this algorithm less compatible with OSPF and
Integrated IS-IS than the standard Router Requirements Algorithm.
Next: E.3.3 The OSPF Algorithm
Connected: An Internet Encyclopedia
E.3.2 The Variant Router Requirements Algorithm