Symptom

ASR920 udp-jitter showing incorrect values for RTT calculation when using BDI interfaces Regular ping from source to destination shows round-trip min/avg/max = 96/96/112 ms, however RTT from operation min (1) /avg (5) which are not the expected values. When we checked the debugs, we found that the T4 timestamp is same for all packets and due to which at one point T1 is greater than T4, which makes IPSLA to think that the clock was adjusted by NTP and the RTT is set to 1ms. Aug 5 17:26:37.042: IPSLA-OPER_TRACE:OPER:1 udp-jitter sourceSeq: 1, destSeq: 1 Aug 5 17:26:37.042: IPSLA-OPER_TRACE:OPER:1 udp-jitter STS: 73596938, RTD: 73596987, STD: 73596987, RTS: 73597001 Aug 5 17:26:37.042: IPSLA-OPER_TRACE:OPER:1 udp-jitter seq=1, rtt=63 . . . Aug 5 17:26:37.061: IPSLA-OPER_TRACE:OPER:1 udp-jitter sourceSeq: 2, destSeq: 2 Aug 5 17:26:37.061: IPSLA-OPER_TRACE:OPER:1 udp-jitter STS: 73596958, RTD: 73597006, STD: 73597006, RTS: 73597001 Aug 5 17:26:37.061: IPSLA-OPER_TRACE:OPER:1 udp-jitter seq=2, rtt=43 . . . . Aug 5 17:26:37.081: IPSLA-OPER_TRACE:OPER:1 udp-jitter sourceSeq: 3, destSeq: 3 Aug 5 17:26:37.081: IPSLA-OPER_TRACE:OPER:1 udp-jitter STS: 73596978, RTD: 73597027, STD: 73597027, RTS: 73597001 Aug 5 17:26:37.082: IPSLA-OPER_TRACE:OPER:1 udp-jitter seq=3, rtt=23 . . . . Aug 5 17:26:37.100: IPSLA-OPER_TRACE:OPER:1 udp-jitter sourceSeq: 4, destSeq: 4 Aug 5 17:26:37.100: IPSLA-OPER_TRACE:OPER:1 udp-jitter STS: 73596997, RTD: 73597046, STD: 73597046, RTS: 73597001 Aug 5 17:26:37.101: IPSLA-OPER_TRACE:OPER:1 udp-jitter seq=4, rtt=4 . . . . Aug 5 17:26:37.122: IPSLA-OPER_TRACE:OPER:1 udp-jitter sourceSeq: 5, destSeq: 5 Aug 5 17:26:37.122: IPSLA-OPER_TRACE:OPER:1 udp-jitter STS: 73597018, RTD: 73597066, STD: 73597067, RTS: 73597001 Aug 5 17:26:37.122: IPSLA-OPER_TRACE:OPER:1 udp-jitter rtt calculated greater than 86000000,probably clock adjusted by NTP Aug 5 17:26:37.122: IPSLA-OPER_TRACE:OPER:1 udp-jitter seq=5, rtt=1

Conditions

ASR920 different 16.9.X versions Sender interface BDI300 ip address 197.0.0.1 255.255.255.0 ip sla 300 udp-jitter 197.0.0.2 10000 source-ip 197.0.0.1 num-packets 500 Responder interface BDI300 ip address 197.0.0.2 255.255.255.0 ip sla responder

Workaround

None

Further Problem Description