North American Network Operators Group

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Re: New router feature - icmp error source-interface [was: icmp rpf]

  • From: Richard A Steenbergen
  • Date: Mon Sep 25 23:56:13 2006

On Tue, Sep 26, 2006 at 02:51:21AM +0000, Fergie wrote:
> So, I'm wondering: What happens when you have a traceroute tool
> that shows you MPLS-lableled hops, too? :-)
> The best (?) of both worls, but I digress...

That doesn't show any more or less data about the path, just some extra 
info about the label that is effectively useless to end users. If TTL 
decrement is not enabled, all of the IP hops are hidden by the tunnel, 
which is the point Chris was making.

But that said, I personally think Cisco MPLS with TTL decrement enabled 
but returning the the same rtt as the penultimate hop for every IP hop 
inside the LSP has caused far more harm to every NOC ticket queue on the 
planet than just hiding the damn things. While we're asking for silly 
features, I can name a LOT of people who would pay good money for a 
dedicated ICMP generating processor on Cisco that doesn't spike every time 
BGP scanner runs. Silencing end users who have figured out how to work 
traceroute (or worse MTR) is worth its weight in gold.

Richard A Steenbergen <[email protected]>
GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC)