Subject: Re: [lisp] ALT and EID blocks (was: lisp Digest, Vol 13, Issue 10)

From: [email-masked] (Noel Chiappa)
Date: Fri, 4 Dec 2009 21:45:36 -0500 (EST)

> From: Charrie Sun <[email-masked]>

    > can anyone tell me how to set each ALT node responsible for mappings
    > for certain EID blocks?

ALT nodes (other than Map-Servers, which are ALT leaves) don't originate any
EID blocks into the ALT (although ALT nodes which are higher in the
'hierarchy' may aggregate several EID blocks together, replacing several
smaller ones with one larger one).

Map-Servers originate EID blocks into the ALT based on Map-Registers that
they receive from client ETRs. (Note that Map-Rehgistration is protected by
cryptographic authentication which has to be configued into each end, so it's
not a trivial DoS vector).

    > If they do it spontaneously, wouldn't it just like BGP, and each node
    > contains a full mapping table?

Well, to start with, a clarification: ALT nodes (even Map-Servers) do not
actually contain mappings. They just contain (and the ALT computes) _paths_ to
ETRs which are authoritative for mappings - i.e. the mappings are always
actually in the ETRs.

Each ALT node does contain 'routing tables' which do contain all the blocks
of the EID namespace for which some ETR somewhere has mappings. Was that
what you are asking?

	Noel

---

From: Charrie Sun <[email-masked]>
Date: Sat, 5 Dec 2009 15:54:41 +0800

Yes, that's exactly what i was asking. Apologize for the mistaken words of
"each node contains full mapping table", what i mean is that each ALT node
contains routes to ETRs of the whole EID namespace. Wouldn't that be huge?
My idea is to clearly define the structure of the ALT system, as to the
layer number and node degree, so each ALT node need only to know a few nodes
(ancestors and children) and communicate with them. Is that necessary?

2009/12/5 Noel Chiappa <[email-masked]>