[Babel-users] [babel] source sub-tlv

[Matthieu Boutier]

> I still do find (1) wasteful.

I really would like to feel your intuition.  From my point of view:

  - either you'll have very few some-specific routes, in which case the
    waste is negligible (isn't it the case of multihomed networks ?),

  - or you'll have so much some-specific routes that non-specific routers
    will be almost useless (and so you'll have to update them).

> (3) isn't that simple to define.

> How about Proposal 5, which I define as:
> 

> By default, a vanilla wildcard request triggers a dump of all
> regular routes (by regular I mean from the original spec so
> not source-specific). We define a new non-mandatory sub-TLV
> on Route Requests called "Requested Route Types" that
> contains an array of all the types of routes this request is requesting.

You need to say that routes resulting in a combination of extensions are
sent if each type of the extension is understood.  (and if the node
understand such combination, but this is straightforward).

> 0 = Regular
> 1 = Source-Specific
> 2 = TOS-specific
> etc.
> 
> For example, if you send:
> [Type = TBD, Length=2, 0, 1]
> it means that you'd like all regular and source-specific routes.

and if you send [type = RRT, length=2, 1, 2], it means that you'd like
source-specific routes, ToS-routes and source-tos-routes.  Of course,
if the requesting node doesn't understand the combination, it might
receive a some wasteful routes...

And, even if state is evil, this request can be encoded as the following
by requesting that wildcard requests are combined in the whole message.

    [Wildcard Route Request + source-specific sub-TLV]
    [Wildcard Route Request + ToS-specific sub-TLV]

In the babeld code, I would just put an int to handle that...  Does this
make a 6th proposition ?

> Thoughts?

Summary:

  1. Put one Wildcard Route Request (WRR).  May waste routes.  No parser
     state.

  3. Put one WRR per extension and per combinations.  No wasted routes.
     No parser state.

  5. Define a new sub-TLV with one field per extension.  Send understood
     combinations.  Might waste routes.  No parser state.

  6. Put one WRR per extension.  Send understood combinations.  Might
     waste routes.  Have a parser state (an int is clearly sufficient).

I think I prefer 6 over 5.  (My preferences are: 1 < 6 < 5 < 3).

Matthieu