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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: Refusing Pings on Core Routers??? A new trend?
IIRC, this is not news. - ferg -- "Rubens Kuhl Jr." <[email protected]> wrote: > template response -- I hear is "Well, you can't rely on traceroute > because of ICMP prioritisation". When you start to explain how > traceroute actually works (both ICMP-based and UDP-based (which > still relies on ICMP responses, of course!)), and that ICMP prio > should only affect the IP of which the router listens on (and not > hops beyond or at the dest), most NOCs fire back with another If I recall well, Cisco GSRs impose low priority and/or limits for all ICMP traffic flowing thru the box, not just packets to/from router itself, and there's not a knob to adjust that. Also of notice is that packets that expire TTL needs some kind of low-path processing, and will be subject to increased latency or loss compared to normal ones, and this affects every tool to trace packets thru the network I've seen. -- "Fergie", a.k.a. Paul Ferguson Engineering Architecture for the Internet fergdawg(at)netzero.net ferg's tech blog: http://fergdawg.blogspot.com/ |