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packet loss when ICMP ping

bensonlei
Level 1
Level 1

Hi, experts,

Intermittent packet loss ( request timed out ) is found when I do ping test between two Cisco devices (one is Cat3850-Sw01, another is unknown Cisco device-Sw02).

Temporarily, the following results are found during the ping test (from Sw01 to Sw02):

1. no packet loss with 64bytes to 500bytes packet size

2. packet loss with larger than 500bytes packet size, says 800, 1000...1500bytes

3. no any error from switches interfaces ( as the following captured - for both switches )

 

Any advice or recommendation, many thanks in advance.

 

 

 

 

 

1 Accepted Solution

Accepted Solutions

Hi,

The issue could be related to the storm-control commands you have under the interface. So, for testing please remove these commands and run the ping test again.

storm-control broadcast level bps 10m
storm-control multicast level bps 10m
storm-control unicast level bps 600m
storm-control action shutdown
storm-control action trap

HTH

View solution in original post

8 Replies 8

Deepak Kumar
VIP Alumni
VIP Alumni

Hi,

Are you facing any service slowness issue? 

 

We need more information as to What is QoS configuration on Sw02 (If any), MTU size, CPU utilization, etc. 

Regards,
Deepak Kumar,
Don't forget to vote and accept the solution if this comment will help you!

Hi, Deepak Kumar,

Thanks for your quick reply,

 

Sw01 interface connects to Sw02 interface in the same VLAN, no hop/route between these two interfaces.

 

The switches are configured with default setting, default MTU = 1500, CPU utilization is always under 30%, no QoS and no policy-map configuration, FIFO is default..

 

In fact, the switches configurations are simple, and no resilient network configuration, and

1. Ping response time (rtt, latency ) is not felt slow, for example, rtt < 150ms

2. Network service does not fell slow 

 

With regards

 

 

 

Reza Sharifi
Hall of Fame
Hall of Fame

Hi.

The output of the interface looks clean. Can you post the output of "sh run" from both switches?

Also, is this the command you are using to test?

ping <ip address> size 1500 df-bit

HTH

Hi, Reza Sharifi,

 

I tried the extended ping with "df" set or not set, but the result is same packet loss (not many, just 1 or 2% packet loss when the packet size > 500bytes ).

 

The following configuration is our switch interface ( the second line/resilient line is unplugged at pingtest, so no spanning tree is needed to be concerned ):

interface GigabitEthernet1/0/18
description To_HF_VL888-9__500Mb_line_01
switchport trunk allowed vlan 888-890
switchport mode trunk
storm-control broadcast level bps 10m
storm-control multicast level bps 10m
storm-control unicast level bps 600m
storm-control action shutdown
storm-control action trap
spanning-tree vlan 888-889 port-priority 144
spanning-tree vlan 888-889 cost 3
!

 

The opposite switch is not ours, configuration can not be seen. but these two switches are connected with 10m UTP cable.

 

with many thanks

 

 

 

Hi,

The issue could be related to the storm-control commands you have under the interface. So, for testing please remove these commands and run the ping test again.

storm-control broadcast level bps 10m
storm-control multicast level bps 10m
storm-control unicast level bps 600m
storm-control action shutdown
storm-control action trap

HTH

Great, the problem of packet loss is due to the configuration of the storm-control.

 

Great thanks of your guys, cheers

Glad to help

Good Luck!

Hi friend, 

Well sounds really strange, i think maybe you have a problem about tcp adjust-mss. Try to check this part and define de max size of a packet and check if in both devices are equal. i copy a link to more info about this topic.

Hope find the problem and solve the problem.

https://www.cisco.com/en/US/docs/ios-xml/ios/ipapp/command/ip_tcp_adjust-mss_through_ip_wccp_web-cache_accelerated.html#:~:text=The%20ip%20tcp%20adjust%2Dmss%20command%20helps%20prevent%20TCP%20sessions,size%20argument%20is%201452%20bytes.

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