Robin,
In "Re: [RRG] Re: Aggregation Implies Provider Dependence (LISP-ALT) & Ivip dependencies too", Brian Carpenter wrote:However, user expectations are of a noticeable delay between dialling a phone number and hearing the ringing tone. So e2e lookup solutions to both number portability and roaming are tolerable. If we're prepared to tolerate such a delay in initial identifier-to-locator lookup, why are we having this conversation? (And note that Mobile IP effectively *does* use such a solution.)A scheme such as ALT will also delay some of the DNS (identifier to locator) lookups, since some DNS servers will be on EID space which the ITR has no mapping for. I think there at at least two reasons we should be concerned about the delay problems inherent in a map-encap scheme which depends on any kind of global query server network (LISP-CONS, LISP-ALT or Bill Herrin's TRRP): 1 - Great reluctance to introduce or impose any new architecture which further delays the establishment of communications.
I completely disagree for two reasons. First, applications are used to have a small delay before the first packet flows, this delay has been introduced by the DNS a long time ago. I guess that some people were worried by the added delay at that time, but the benefits of the DNS are clearly more important than this additional second. Second, the delay is only encountered for the *first packet* that needs a mapping. With a router based solution such as LISP, many flows will benefit from the mapping learned from previous flows on the routers.
2 - Concern that if the new kind of address space involves
extra delays of any measurable kind - especially when they
are perceptible by end-users - that this will be a serious
and perhaps fatal barrier to the widespread adoption of the
new kind of address space.
A new architecture will bring new benefits and some costs in terms of delays for a minor fraction of the packets (0.01% or fewer ?) and somme added overhead due to encapsulation. This added costs must be compared to the benefits of the new architecture.
Olivier -- http://inl.info.ucl.ac.be , Universite catholique de Louvain, Belgium -- to unsubscribe send a message to rrg-request@psg.com 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