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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: inter-domain link recovery
On Aug 14, 2007, at 9:06 PM, Chengchen Hu wrote: 1. Why BGP-like protocol failed to recover the path sometimes? Is it mainly because the policy setting by the ISP and network operators? There are an infinitude of possible answers to these questions which have nothing to do with BGP, per se; those answers are very subjective in nature. Can you provide some specific examples (citing, say, publicly-available historical BGP tables available from route-views, RIPE, et. al.) of an instance in which you believe that the BGP protocol itself is the culprit, along with the supporting data which indicate that the prefixes in question should've remained globally (for some value of 'globally') reachable? Or are these questions more to do with the general provisioning of interconnection relationships, and not specific to the routing protocol(s) in question? Physical connectivity to a specific point in a geographical region does not equate to logical connectivity to all the various networks in that larger region; SP networks (and customer networks, for that matter) are interconnected and exchange routing information (and, by implication, traffic) based upon various economic/contractual, technical/operational, and policy considerations which vary greatly from one instance to the next. So, the assertion that there were multiple unaffected physical data links to/from Taiwan in the cited instance - leaving aside for the moment whether this was actually the case, or whether sufficient capacity existed in those links to service traffic to/from the prefixes in question - in and of itself has no bearing on whether or not the appropriate physical and logical connectivity was in place in the form of peering or transit relationships to allow continued global reachability of the prefixes in question. 2. What is the actions a network operator will take when such failures occures? Is it the case like that, 1)to find (a) alternative path(s); 2)negotiate with other ISP if need; 3)modify the policy and reroute the traffic. Which actions may be time consuming? All of the above, and all of the above. Again, it's very situationally dependent. 3. There may be more than one alternative paths and what is the criterion for the network operator to finally select one or some of them? Proximate physical connectivity; capacity; economic/contractual, technical/operational, and policy considerations. 4. what infomation is required for a network operator to find the new route? By 'find the new route', do you mean a new physical and logical interconnection to another SP? The following references should help shed some light on the general principles involved: <http://en.wikipedia.org/wiki/Peering> <http://www.nanog.org/subjects.html#peering> <http://www.aw-bc.com/catalog/academic/product/ 0,1144,0321127005,00.html> ----------------------------------------------------------------------- Roland Dobbins <[email protected]> // 408.527.6376 voice Culture eats strategy for breakfast. -- Ford Motor Company
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