On Thu, Jul 24, 2008 at 8:23 AM, Jari Arkko <[EMAIL PROTECTED]> wrote: > Second, even if you believe that we DO need a cache, there's really no > reason why the cache design has to be cast into the rest of the > architecture. Even if your forwarding ASIC can't employ enough memory for > all the entries, I have a hard time convincing myself that we can't have a > general purpose computer sitting next to it that holds the full table. I'm > writing this on a laptop that has a 160G disk. That would be enough for > several mapping tables containing EVERY IPV4 ADDRESS.
Jari, You make an assumption here: that the ID->Locator map can be made to remain static over a reasonable period of time. In other words, the map would only change when someone contracts a new ISP to provide one of the loctators that reaches them. Ephemeral changes to routing due to link failures and the like would impact the topology RIB but not the map. Were this not the case, the amount of static storage would be irrelevant because you'd have to be able to push updates to the map to reflect current ID reachability via each registered locator. Unfortunately, this assumption is trivially demonstrated to be false. Disconnection between a node and one or more of it's locator-trees will be a routine event. A local T1 drops. Boom, disconnected. For the map to remain static, something up the locator tree would need to be able to -reliably- return a negative acknowledgment to the ITR indicating that the node is not currently reachable via that locator. But we already know negative acknowledgments can't be made to generate and return reliably during an outage event. In any operational system, we get unexpected routing loops or a firewall blocks the way or a router malfunctions or the network is congested or something else happens so that the packet is silently dropped without a NAK. That's why we detect outages through the absence of positive acknowledgment instead. Regards, Bill Herrin -- William D. Herrin ................ [EMAIL PROTECTED] [EMAIL PROTECTED] 3005 Crane Dr. ...................... Web: <http://bill.herrin.us/> Falls Church, VA 22042-3004 -- to unsubscribe send a message to [EMAIL PROTECTED] with the word 'unsubscribe' in a single line as the message text body. archive: <http://psg.com/lists/rrg/> & ftp://psg.com/pub/lists/rrg
