nanog mailing list archives
Re: packet loss question
From: jmkeller <jmkeller () houseofzen org>
Date: Fri, 08 Jul 2016 11:42:00 -0400
On 2016-07-07 11:53 PM, William Herrin wrote:
On Thu, Jul 7, 2016 at 3:52 PM, Ken Chase <math () sizone org> wrote:ICMP is allowed to be dropped by intervening routers. Someone will quote an RFCat us shortly.Hi Ken, That's not correct. Routers might not generate an ICMP time-exceeded packet for every packet whose TTL reaches zero, but that's not the same thing. Routers dropping ICMP packets in transit would be bad. Protocols like TCP depend on path MTU discovery and path MTU discovery critically depends on ICMP. Regards, Bill Herrin
All we are seeing here is control plane filtering by intermediate routers. Unless packet loss numbers start at a router and hops past it show the same or higher losses it's not an actual issue with the transport path at that hop. Outside of your own domain of administrative control, you can't rely on intermediate routers responding to ICMP (either filtered completely or rate limited responses).
-- James
Current thread:
- packet loss question Phillip Lynn (Jul 07)
- Re: packet loss question Job Snijders (Jul 07)
- Re: packet loss question Ken Chase (Jul 07)
- Re: packet loss question William Herrin (Jul 07)
- Re: packet loss question Ken Chase (Jul 08)
- Re: packet loss question William Herrin (Jul 08)
- Re: packet loss question jmkeller (Jul 08)
- Re: packet loss question William Herrin (Jul 07)
- Re: packet loss question Phillip Lynn (Jul 08)
- Re: packet loss question Mel Beckman (Jul 08)
- Re: packet loss question Mark Andrews (Jul 10)
- Re: packet loss question cpolish (Jul 11)
- Re: packet loss question Sean Donelan (Jul 12)
- Re: packet loss question cpolish (Jul 12)
- Re: packet loss question James R Cutler (Jul 07)
- Re: packet loss question Mel Beckman (Jul 07)