Giants and Input Errors on WAN interface from Carrier side

ahmad82pkn · ‎07-02-2015

Hi we has Cisco ASR 1002-x that is connected to mpls cloud .

we are having input errors on WAN interface gi0/0/0 and they are equal to number of giant Packets.

since its on WAN side i cant put any sniffer, is there a way i can find out source of these giant packets? any way to find it from router commands?

i have already reported it to carrier, if they can help in finding it.

below are stats, any help would be appreciated.

ASR1002-#sh int gi0/0/0
GigabitEthernet0/0/0 is up, line protocol is up
Hardware is 6XGE-BUILT-IN, address is 74a2.e668.7500 (bia 74a2.e668.7500)
Description: 500 MEG : Circuit ID :
Internet address is
MTU 1500 bytes, BW 500000 Kbit/sec, DLY 10 usec,
     reliability 255/255, txload 76/255, rxload 39/255
Encapsulation ARPA, loopback not set
Keepalive not supported
Full Duplex, 1000Mbps, link type is auto, media type is SX
output flow-control is on, input flow-control is on
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:09:27, output 00:09:27, output hang never
Last clearing of "show interface" counters 00:27:40
Input queue: 0/375/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: Class-based queueing
Output queue: 0/40 (size/max)
5 minute input rate 77945000 bits/sec, 77741 packets/sec
5 minute output rate 150357000 bits/sec, 83811 packets/sec
     130619173 packets input, 16270779782 bytes, 0 no buffer
     Received 0 broadcasts (0 IP multicasts)
     0 runts, 766 giants, 0 throttles
     766 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 0 multicast, 0 pause input
     142597727 packets output, 33575778366 bytes, 0 underruns

Leo Laohoo · ‎07-02-2015

The input errors/giants vs the amount of packets input is insignificant, however, noticed that you've just cleared the counters 27 minutes earlier. Input errors usually means there's a setting upstream from the carrier which you are not aware of.

ahmad82pkn · ‎07-03-2015

i have opened ticket with carrier, but so far they are giving standard statements, no problem at their end.

i was just hoping if there is some minimal level debug which can tell me source IP address of these Giant packets :(

or since across this MPLS cloud my 20 sites are connected, this is possible that some device from those remote location sending giant packets, if there a way i can login to each remote site router and use some command to find out outgoing giant packets?? i mean which site is sending giants? if i can find that then i can enable local sniffer on the site to find actual source.

any thoughts?

ahmad82pkn · ‎07-09-2015

carrier is saying its normal, and if you want to accept Giants, then increase MTU of your router interface, and then put sniffer on LAN side to see who are sending Giants and then tackle accordingly. hmmmmmmmm