(re)use of AS numbers in 6bone routing?

[Bill Manning]

> > the topic, but the old discussing seems to be about the ASN in
> > provider-based address, not the ASN in BGP4+.
> >       Can anyone answer my question? Thanks a lot.
> 
> You should be able to use private AS numbers to peer with your
> upstream (me) and any downstreams with whom you might also peer
> -----------------------------------------------
> 
> 
> In my opinion, I guess it is only required that the ASNs among your upstream and downstream
> are unique. Because after the aggregation, when your upstreams change BGP4+ routing information,
> there are no your ASN in the information.
> 
> But the above is only what I quess. Hope there is other opinion about this.
>                                         Chu
> 

You may use private ASNs.  However ASN re-use applies to BGP (and all its
varients). IP versions are irrelevent here.  BGP will detect duplicates
in the path. Most operators treat this as a routing loop and will 
suppress the route.  RTFM on BGP folks.

ASNs show up in some tools...:

Note that the ASN is shown and changes between administrative boundaries.
ASN 1740 only appears in a single set. If it was to show up either before 
AS 226 or after AS 701, then there is a loop.


Tracing the route to ns.ripe.net (193.0.0.193)

  1 triton.cerf.net (198.32.146.20) [AS 226] 4 msec 0 msec 0 msec
  2 atm11-0.lax-bb1.cerf.net (134.24.29.17) [AS 1740] 0 msec 0 msec 4 msec
  3 pos8-0-155M.lax-bb4.cerf.net (134.24.32.230) [AS 1740] 0 msec 4 msec 4 msec
  4 pos6-0-622M.sfo-bb3.cerf.net (134.24.29.233) [AS 1740] 12 msec 12 msec 12 msec
  5 pos4-0-0-155M.sjc-bb3.cerf.net (134.24.32.90) [AS 1740] 12 msec 16 msec 12 msec
  6 atm8-0-155M.sjc-bb1.cerf.net (134.24.29.37) [AS 1740] 16 msec 16 msec 16 msec
  7 San-Jose1.CA.US.EU.net (198.32.136.28) [AS 701] 80 msec 76 msec 76 msec
  8 Sfr-nr01.CA.US.EU.net (134.222.228.18) [AS 286] 156 msec 76 msec 76 msec
  9 Nyk-nr01.NY.US.EU.net (134.222.228.177) [AS 286] 76 msec 76 msec 80 msec
 10 Ldn-nr04.UK.EU.net (134.222.228.157) [AS 286] 144 msec 144 msec 144 msec
 11 Ldn-nr03.UK.EU.net (134.222.160.3) [AS 286] 144 msec 144 msec 144 msec
 12 Asd-nr02.NL.EU.net (134.222.228.129) [AS 286] 340 msec 260 msec 148 msec
 13 s01.overtoom.ripe.net (134.222.249.82) [AS 286] 256 msec 292 msec 224 msec
 14 s10.pampus.ripe.net (193.0.0.54) [AS 3333] 180 msec 172 msec 172 msec
 15 ns.ripe.net (193.0.0.193) [AS 3333] 172 msec 172 msec 172 msec


-- 
--bill