On Fri, Sep 16, 2011 at 2:42 PM, Steve Bohrer <skbohrer@simons-rock.edu> wrote:
Can I expect that backbone routers should never give me timeouts on a traceroute through them, so, lots of asterisks from these systems indicate a packet loss problem that needs to be fixed?
something inside the router has to make the icmp-unreachable-ttl-expired, right? perhaps that thing is rate-limited (in hardware/software) so that a line-rate flood of ttl=1 packets won't induce an outbound dos attack effect? perhaps that is a shared resource among all of the ports on the pic/card/chassis? perhaps the function that does this does more than just make ttl-expired? (other error codes or other ancillary functions)
Or, are these traceroute asterisks essentially meaningless, and should be expected on any busy link?
think router not link, but.... probably less important that you don't see ttl-expired messages, but that you do see no packet loss/mal-effects with the protocols you care about (ping? http? smtp?) it's also possible that the destination has requested gblx to filter udp toward it (depending on what sort of a day they are having and how much fun gblx wants to incur) -chris