On Mon, May 24, 2010 at 10:48 AM, Joel M. Halpern <[email protected]> wrote: > I understood you were using Node Address only within the AS. > (We won't explore the question of how you put the destination AS number and > destination address into the packet, as that is minor compared to the other > issues.)
The DST address will be put in the usual DST IP address field. Where to put the AS numbers (both SRC and DST) will be an implementation issue. I'd prefer to put in the IP option field, but there were opinion that most current routers simply ignore any IP options. Or put it in the net mask field > > You ddi not comment on the fact that AS granularity is just the wrong > granluarity. Wrong in what sense? In regards to traffic engineering(TE)? In the IDR level, although only AS# will be used for routing, the whole packet header is still visible. So, if you'd want to apply any TE at as deep as node address, you can still do that since (src addr, src as; dst add, dst as) are all visible to inter-domain routers. > > You also seem to have misunderstood my large comment. I will presume that > the AS is to include the last serving ISP and all of their customers. Here, I might not be precise what I mean by AS. Should I call it a domain: o AS is an entity which will have its independent authority to assign addresses to the nodes inside the AS. o Also, each AS will choose whatever intra-domain routing as it serves its purpose. > If instead you intend that every site have its own AS, then Tony's comment > about the large number of AS numbers you get is, if anything, understated. Perhaps. But, is the size of the table the real threat? - With 16-bit AS, the table entry will be < 2**16(16K) - With 32-bit AS, it will be < 2**32(64M) Assuming 1KB for each entry vector, the memory will be - 16MB or 64GB I'd assume these are affordable sizes for IDR routers which should usually be heavy machines. The remaining problem is to look-up speed, for which there's be a whole lot of tricks. The real problem, from my perspective, might be that we now use intra-domain node addresses in finding paths in inter-domains. You scan the table at the granularity of node address. Although you're using net prefixes, they are derived from node addresses. I'd say using address which belongs to the inter-domain, that is AS or domain address, should be the granularity in IDR. > So, assuming that the AS includes its end-site customers, then in order for > the AS to route on node-IDs, which are not derived topologically from points > of connectivity to the topology, that implies that the AS as a whole is > flat-routing on the ID space of ALL the nodes in ALL the sites served by > that AS. Sorry, that simply will not work. Here, we're talking about intra-domain routing, aren't we? If you'd mean 'operate' by 'work', I'd say it should work, why not. If you'd mean 'the address space to be handled by an AS is too big', then I'd partly agree. But, for example, even for a 'conventional' A-class AS, the node address space will be limited by 2**24. For most AS's, a size of 2**16 or a few multiples of it might suffice. The burden on the intra-domain routers is to keep managing table of this size. So, TOO big, you mean? > > Yours, > Joel M. Halpern > > Dae Young KIM wrote: >> >> Joel, >> >> You're misunderstanding my description. I admit my slides are short of >> wordings. >> >> - Node addresses are local to each AS, so each AS manages only their >> own member list. ASs don't keep full list of all hosts in all >> customers. >> >> - As soon as a packets exits an AS to the inter-domain region, the >> node address loses its meaning(or is not relevant), and the IDR >> routers would only look at the dst AS# imbedded in the packet to >> execute IDR. >> >> On Sun, May 23, 2010 at 11:53 PM, Joel M. Halpern <[email protected]> >> wrote: >>> >>> You are treating the AS Number as your locator. >>> As has been discussed on this list, that has the wrong granularity for >>> operators needs. >>> >>> More importantly, you are requiring that each AS keep of full list of all >>> hosts in all customers. Not only do enterprises not want to provide this >>> ifnormation to their operators, but that is potentially a VERY large >>> amount >>> of information. Which operators do not want to have to distribute across >>> the entire AS. (Even residential operators would not want to have to >>> distribute the IDs of every host at every home across their entire AS.) >>> >>> Yours, >>> Joel >>> >>> Dae Young KIM wrote: >>> ... >>>> >>>> - All this can be done without padding locators (or addr of subnet >>>> router) to each packets. Packets carry only node address and AS numbers >>>> instead, the latter not being used within an AS but only to be used for >>>> IDR. >>>> >>> .... >>> >> >> >> > -- DY _______________________________________________ rrg mailing list [email protected] http://www.irtf.org/mailman/listinfo/rrg
