Re: Packet drop/loss

ndomo1414 · ‎02-22-2023

Hi Team,

Kindly help me I packet loss, on my p2p link.

#ping si 1500 re 100

Type escape sequence to abort.

Sending 100, 1500-byte ICMP Echos to , timeout is 2 seconds:

!!!!!!!!.!!!!!!!.!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!..!.!!!!!!!!!!!!!

!.!!!!!!!!.!!!!!!!!!.!!!!.!!!!

Success rate is 89 percent (89/100), round-trip min/avg/max = 36/67/96 ms

Below is the show interface results. Please help what could be the reason.

#sh int Gi0/0
GigabitEthernet0/0 is up, line protocol is up
Hardware is CN Gigabit Ethernet, address is
MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation 802.1Q Virtual LAN, Vlan ID 1., loopback not set
Keepalive set (10 sec)
Full Duplex, 1Gbps, media type is RJ45
output flow-control is unsupported, input flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:00, output 00:00:00, output hang never
Last clearing of "show interface" counters 6w0d
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 31
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 592000 bits/sec, 130 packets/sec
5 minute output rate 155000 bits/sec, 123 packets/sec
296453997 packets input, 3958218031 bytes, 0 no buffer
Received 482 broadcasts (0 IP multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 0 multicast, 0 pause input
291592942 packets output, 610570871 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 unknown protocol drops
0 babbles, 0 late collision, 0 deferred
1 lost carrier, 0 no carrier, 0 pause output
0 output buffer failures, 0 output buffers swapped out

#sh int Gi0/0.606
GigabitEthernet0/0.606 is up, line protocol is up
Hardware is CN Gigabit Ethernet, address is

Internet address is
MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation 802.1Q Virtual LAN, Vlan ID 606.
ARP type: ARPA, ARP Timeout 04:00:00
Keepalive set (10 sec)
Last clearing of "show interface" counters never

MHM Cisco World · ‎02-22-2023

you make icmp data 1500 but what about the frame/packet overhead
you need at least 40 below 1500 mtu value for ping to success

Joseph W. Doherty · ‎02-22-2023

"you make icmp data 1500 but what about the frame/packet overhead "

I believe1500 is the correct value to use on a Cisco switch/router (other vendors, though, do need you to allow for L3 overhead; Microsoft comes to mind, see MTU and ping size confusion ).

"you need at least 40 below 1500 mtu value for ping to success "

Suspect you accidently were thinking of IP/TCP, 20 + 20, overhead. For IP/ICMP overhead should be 20 + 8, see Understanding Guide to ICMP Protocol with Wireshark .

Joseph W. Doherty · ‎02-22-2023

You've provided insufficient information to suggest likely causes, but just looking at your min/avg/max ping times, and the fact your gig interface has recorded some drops, there might be drops anywhere along the path, due to transient congestion, to whatever you're pinging just doesn't want to respond to all your pings.