Dave,So in order to preserve the behavior you are describing, the packet needs to be routed over the RLOC space as early as possible. This corresponds to placing the ITRs deeper in the site (closer to the source hosts). Since the ITR will encapsulate the packet (and the outer header destination address will be a locator), it will find the best exit just as it does today.What would be the benefit and driver for such large corporate sites to install ITRs ?Finer-grained control over exit policy without having to propagate global state inside your enterprise.But what you and Tony replied are not the mirror replacement of today's optimal routing to dst prefix ... this is optimal closest exit strategy or in other words ability to find closest ITR. I am not aware about an ITR to ITR relays for optimal routing towards destination in any of the current proposals :).
Robert, I think you didn't get Dave's point. Let me restate a bit:o If you put the ITRs at the edges of a source site, then you route on the EID from the source host to the edge LISP router. In this case you get to exit
based on the default route, which is through the closest LISP router.o When you want to get shortest path to the destination EID based on the locators the destination site has provide to the source site, you put the ITRs, say in the middle of the source site. When you do that, the packet is routed based on EID to the ITRs. But from that point on you route based on the locator. So the exit router the packet travels through is based on the shortest path
to the destination locator.o If you put the ITRs directly connected to the sources, one or more on each source subnet, you get destination based shortest paths just like you do today.
But getting what you do today is at the cost of carrying full routes in the source site. So if you place your ITRs at the core of the source site, you can get good paths to each external destination without carrying full routes *throughout* your source site.
So it will actually be less cost to do what you are doing today. You don't need full routes everywhere, and you probably won't need iBGP everywhere as well.
I wonder why so many networks today still run full BGP inside rather then just injecting whole bunch of even anycast defaults into their IGP to ASBRs. It would be nice to have such public data :).
They want shortest paths to reduce latency and packet delay. Especially the big content providers where competition is fierce for low latency and giving the user the best user experience.
Perhaps engineers of such networks should speak up on their reasons as I can not disclose neither the names nor their internal network architecture fundamentals ...
Yes, many would welcome that. Dino -- 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