I generally prefer denser encodings. does the bird implementation do any extensive ae?
On Tue, Mar 31, 2020 at 10:41 AM Juliusz Chroboczek <[email protected]> wrote: > > Dear all, > > Some of you might remember that Théo Bastian (in copy of this mail) is > working on implementing a Babel extension for IPv4 routing with IPv6 next > hops. Since the extension is meant to interoperate with other Babel > routers, we've decided to encode IPv4-over-IPv6 routes as a new AE. So an > IPv4-over-IPv6 route announcement consists of: > > 1. a normal Router-ID TLV ; > 2. an IPv4-over-IPv6 Next Hop TLV carrying an IPv6 next-hop ; > 3. an IPv4-over-IPv6 Update TLV carrying an IPv4 prefix. > > The Update is encoded in the new AE, which updates a separate set of > compression state; the normal IPv4 compression state is left undisturbed. > On the other hand, we have two natural ways of encoding the NH : > > (1) use a new NH, in the new AE ; > (2) reuse the IPv6 NH (AEs 1 and 2). > > Encoding (1) has the advantage of being easier to explain. Encoding (2) > has a number of advantages: > > (i) if a packet carries both IPv4 and IPv6 routes, the next-hop is only > encoded once; > > (ii) we can use both AEs 1 and 2, which means that we can use the more > compact encoding for link-local next-hops ; > > (iii) the code is slightly simpler. > > Initially, Théo preferred encoding (2), while I was in favour of (1). > Théo rewrote all of his code in style (1), and after looking at his code, > I'm having second thoughts. > > Does anyone have any good arguments one way or the other? Scratch this -- > does anyone have any arguments, not necessarily good? > > -- Juliusz > > _______________________________________________ > Babel-users mailing list > [email protected] > https://alioth-lists.debian.net/cgi-bin/mailman/listinfo/babel-users -- Make Music, Not War Dave Täht CTO, TekLibre, LLC http://www.teklibre.com Tel: 1-831-435-0729 _______________________________________________ Babel-users mailing list [email protected] https://alioth-lists.debian.net/cgi-bin/mailman/listinfo/babel-users
