Sometimes this is usually due to high CPU time on the target device. If the device is under heavy load, the ICMP Echo process gets lowest priority. With a well-known name server like 4.2.2.2, this seems unlikely. It could be an intermediate hop or a routing loop, Do a traceroute to get more detailed per-hop statistics.
-mel ________________________________ From: NANOG <nanog-bounces+mel=beckman....@nanog.org> on behalf of Jason Iannone <jason.iann...@gmail.com> Sent: Wednesday, December 21, 2022 9:10 AM To: North American Network Operators' Group <nanog@nanog.org> Subject: Large RTT or Why doesn't my ping traffic get discarded? Here's a question I haven't bothered to ask until now. Can someone please help me understand why I receive a ping reply after almost 5 seconds? As I understand it, buffers in SP gear are generally 100ms. According to my math this round trip should have been discarded around the 1 second mark, even in a long path. Maybe I should buy a lottery ticket. I don't get it. What is happening here? Jason 64 bytes from 4.2.2.2<http://4.2.2.2>: icmp_seq=392 ttl=54 time=4834.737 ms 64 bytes from 4.2.2.2<http://4.2.2.2>: icmp_seq=393 ttl=54 time=4301.243 ms 64 bytes from 4.2.2.2<http://4.2.2.2>: icmp_seq=394 ttl=54 time=3300.328 ms 64 bytes from 4.2.2.2<http://4.2.2.2>: icmp_seq=396 ttl=54 time=1289.723 ms Request timeout for icmp_seq 400 Request timeout for icmp_seq 401 64 bytes from 4.2.2.2<http://4.2.2.2>: icmp_seq=398 ttl=54 time=4915.096 ms 64 bytes from 4.2.2.2<http://4.2.2.2>: icmp_seq=399 ttl=54 time=4310.575 ms 64 bytes from 4.2.2.2<http://4.2.2.2>: icmp_seq=400 ttl=54 time=4196.075 ms 64 bytes from 4.2.2.2<http://4.2.2.2>: icmp_seq=401 ttl=54 time=4287.048 ms 64 bytes from 4.2.2.2<http://4.2.2.2>: icmp_seq=403 ttl=54 time=2280.466 ms 64 bytes from 4.2.2.2<http://4.2.2.2>: icmp_seq=404 ttl=54 time=1279.348 ms 64 bytes from 4.2.2.2<http://4.2.2.2>: icmp_seq=405 ttl=54 time=276.669 ms
