No relevant resource is found in the selected language.

This site uses cookies. By continuing to browse the site you are agreeing to our use of cookies. Read our privacy policy>

Reminder

To have a better experience, please upgrade your IE browser.

upgrade

ME60 cpu-defend policy configration for ICMP packets caused ping lost packets

Publication Date:  2012-07-27 Views:  113 Downloads:  0
Issue Description
T Operator in Malaysia is using ME60-16 as Bras. Triple-play services are running on platform such as high speed internet, VoIP and VoD.

Software version: V6R2C02SPC500
Board: BSUF-21

Topology:Refer to the image.
Alarm Information
Null
Handling Process
 
Applied cpu-defend policy 20 to slot 10:
#
slot 10
cpu-defend-policy 20
#
 
Configure the icmp cir value to 16 kbps:
#
cpu-defend policy 20
 car icmp cir 16
#
 
 
CIR Configuration:
16 kilobits per second
 
Fast ping with large buffer size (time interval = 10 ms):
1 second = 1000 milliseconds = 100 * 10 ms
100 * 2048 bytes = 204800 bytes per second
                            = 1638 kilobits per second
 
Normal MS-DOS ping with normal buffer size (time interval = 2 s):
32 bytes / 2 seconds = 16 bytes per second
= 0.128 kilobits per second
 
Normal MS-DOS ping is 0.128 kbps which is conform to the configured CIR value,
therefore the ICMP packet will be processed. In vice versa, fast ping in this test is
1638 kbps and it does not comply to the CIR value, therefore the ICMP packet will
be discard

Test Result
 
User 1 ping (with large buffer size 2048 bytes) has been dropped
 
 
User 2 ping (with normal buffer size 32 bytes) is not affected







 
CPU utilization on slot 10 has been dropped from 23% to 18% after the CAR ICMP implementation.

 CPU utilization before the CAR ICMP implementation


 
 CPU utilization after the CAR ICMP implementation

 
 

Root Cause
Scenario:

User 1 will perform a continuous fast ping (in 10 milliseconds) with large buffer
size (2048 bytes) to the ME60 uplink interface IP address (58.27.91.1)


 
User 2 will perform a continuous normal MS-DOS ping (default time interval = 2
seconds) with normal buffer size (32 bytes) to the ME60 uplink interface IP
address (58.27.91.1)


 
CPU utilization on slot 10 has been increased from 18% to 23% due to the continuously fast ping with large buffer size.

 \
CPU utilization before the incoming ICMP packet
 


 CPU utilization after the incoming ICMP packet
 

Suggestions
 
The ICMP CIR value configured in this test is a tested value in the LAB to
protect the CPU utilization on processing the ICMP packet. The ICMP CIR
value can be tweaked to meet the optimal value from preventing high
utilization on CPU.
 
This security feature has no impact on the services as it’s only affect the
ICMP packet.
 

END