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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: consistent policy != consistent announcements
2) generally speaking, BGP path length is too blunt an instrument. More fine-grained control is needed to allow peers to fine-tune balance of their interests. I'm sorry to be too naive, but i'm repeating that for years and nobody seems to agree that BGP needs real metrics. How come? Well, for several reasons. First, any such proposal should have a reasonable architecture. Not just a description of the mechanism. Motivational explanations are most welcome, preferably sprinkled with real world examples. Second, there's the issue of the consistency of the values used. As I recall your proposal, each domain in the path would propose a metric for its contribution for a prefix. A receiving domain then weighted each domain in whichever way it chose to arrive at a final, composite metric. Thus, the semantics of the metric are hardly clear. Third, there's the pragmatic issue of implementation cost. Yes, the cost of an integer per AS in an AS path is tolerable, tho not "cheap". This cost becomes painful if most domains are not using the metric. And it becomes more painful if two prefixes with otherwise identical attributes have different metrics. This results in them not landing in the same update, thereby increasing overhead. Are we willing to take a signficant step forward in overhead for this flexibility? Tony - - - - - - - - - - - - - - - - -
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