Доброго дня всем!

Два маршрутизатора 1760 и 2621.
Интерфейсы объединены по оптике. Оптика чужая.
Имею на интерфейсах secondary IP:
1760: 192.168.217.1/30
2621: 192.168.217.2/30
Пускаю пинги различного размера с 1760:
1760#ping 192.168.217.2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.217.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/5/12 ms
1760#ping 192.168.217.2 repe 30 size 300

Type escape sequence to abort.
Sending 30, 300-byte ICMP Echos to 192.168.217.2, timeout is 2 seconds:
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Success rate is 100 percent (30/30), round-trip min/avg/max = 1/3/4 ms
1760#ping 192.168.217.2 repe 30 size 1000

Type escape sequence to abort.
Sending 30, 1000-byte ICMP Echos to 192.168.217.2, timeout is 2 seconds:
......
Success rate is 0 percent (0/6)
1760#ping 192.168.217.2 repe 30 size 500

Type escape sequence to abort.
Sending 30, 500-byte ICMP Echos to 192.168.217.2, timeout is 2 seconds:
.!...!.
Success rate is 28 percent (2/7), round-trip min/avg/max = 4/4/4 ms
1760#ping 192.168.217.2 repe 30 size 300

Type escape sequence to abort.
Sending 30, 300-byte ICMP Echos to 192.168.217.2, timeout is 2 seconds:
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Success rate is 100 percent (30/30), round-trip min/avg/max = 1/3/8 ms
1760#ping 192.168.217.2 repe 30 size 400

Type escape sequence to abort.
Sending 30, 400-byte ICMP Echos to 192.168.217.2, timeout is 2 seconds:
!!!!!!!!!.!!!!!!!!!!!!!..!!.!!
Success rate is 86 percent (26/30), round-trip min/avg/max = 1/4/8 ms

Что бы это значило?