Junos OS

For some odd reason, when I issue ICMP ping on one of our routers w/ a payload larger than 64 byte I get these results:

ping 8.8.8.8 routing-instance internet source 149.15.146.135 size 65
PING 8.8.8.8 (8.8.8.8): 65 data bytes
72 bytes from 8.8.8.8: icmp_seq=0 ttl=45 time=4.922 ms
wrong data byte #64 should be 0x40 but was 0x0
59 1d a9 ab 0 7 2f 3b 8 9 a b c d e f 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f
20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f 30 31 32 33 34 35 36 37 38
72 bytes from 8.8.8.8: icmp_seq=1 ttl=45 time=4.880 ms
wrong data byte #64 should be 0x40 but was 0x0
59 1d a9 ac 0 7 33 b3 8 9 a b c d e f 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f
20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f 30 31 32 33 34 35 36 37 38
^C
--- 8.8.8.8 ping statistics ---
2 packets transmitted, 2 packets received, 0% packet loss
round-trip min/avg/max/stddev = 4.880/4.901/4.922/0.021 ms

With a 64 byte payload I get normal results.

Any pointers?

Hi,


The results you are observing are expected. These kind of results are noticed when the remote server/device is trying to limit the bytes returned in the ICMP response.


To confirm this, I did a quick test in my lab to ping the google external server (216.58.221.238).


Normal ping with size 64 goes fine


lab@lab> ping 216.58.221.238 size 64     
PING 216.58.221.238 (216.58.221.238): 64 data bytes
72 bytes from 216.58.221.238: icmp_seq=0 ttl=43 time=76.962 ms
72 bytes from 216.58.221.238: icmp_seq=1 ttl=43 time=77.085 ms
72 bytes from 216.58.221.238: icmp_seq=2 ttl=43 time=77.132 ms
^C
--- 216.58.221.238 ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max/stddev = 76.962/77.060/77.132/0.072 ms


Once the size is increased, I see similar results.

lab@lab> ping 216.58.221.238 size 100
PING 216.58.221.238 (216.58.221.238): 100 data bytes
72 bytes from 216.58.221.238: icmp_seq=0 ttl=43 time=77.156 ms
wrong data byte #64 should be 0x40 but was 0x0
        59 1e 53 92 0 e 6c 13 8 9 a b c d e f 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f
        20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f 30 31 32 33 34 35 36 37 38 39 3a 3b 3c 3d 3e 3f
        0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
72 bytes from 216.58.221.238: icmp_seq=1 ttl=43 time=77.859 ms
wrong data byte #64 should be 0x40 but was 0x0
        59 1e 53 93 0 e 7b cb 8 9 a b c d e f 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f
        20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f 30 31 32 33 34 35 36 37 38 39 3a 3b 3c 3d 3e 3f
        0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
^C
--- 216.58.221.238 ping statistics ---
2 packets transmitted, 2 packets received, 0% packet loss
round-trip min/avg/max/stddev = 77.156/77.507/77.859/0.352 ms

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