Pekka Savola wrote:
On Fri, 31 Aug 2001, Gert Doering wrote:
On Fri, Aug 31, 2001 at 03:58:04PM +0300, Pekka Savola wrote:
Care to explain how traceroute through these IX's is supposed to work, if the node performing traceroute, ping, or whatever, is not a small-scale customer (ie. default route) of the IX participants?
For a traceroute *through* the IX you don't need the route to that /64. It might get filtered if you do RPF filtering (but multihomed customers usually don't, because it doesn't work), but reachability of the hosts *behind* the IX is not a problem.
RPF is an additional issue, granted, but not the point here.
Traceroute will skip a hop or two, ie. those p-t-p links where these internal addresses are used; these might be crucial when debugging or tracing where the traffic goes.
This might make (depending on the topology) a 15 second wait for the magic '* * *' combination.
After and before these, it will continue in a normal fashion. But boy, would this be annoying..
That depends on how your particular traceroute works. The common approach is to send packets (typically UDP to high-numbered ports) to the _destination_ address with increasing TTLs and look for the ICMP TTL Exceeded message to come back from each intermediate hop -- no traceroute packets are addressed _to_ the intermediate routers. So, unless you're explicitly filtering packets sourced from unrouted address space (e.g. RPF), you'll still get a useful(?) traceroute output. James