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Forum Discussion

Muhammad_Irfan1's avatar
Muhammad_Irfan1
Icon for Cirrus rankCirrus
Nov 27, 2014

Can not ping any self ip or VS with MTU 1500.

My plate form is F5 LTM 5000s with V 11.4.1. I can not ping any selp ip or vs with ping size 1500 I can ping with 1454 but not with any thing larger. MTU in vlan is configured to 1518. How to solve t...
Aung_Thurein_72's avatar
Aung_Thurein_72
Icon for Nimbostratus rankNimbostratus
Mar 05, 2016

This is due to DoS protection feature as mentioned by Vernon. It is explained in this solution article .

 

https://support.f5.com/kb/en-us/solutions/public/15000/300/sol15396.html

 

The solution explains about how to change/increase this maximum limit. The default value for dos.maxicmpframesize is 1500.

 

However, that does not mean that it will allow the ICMP payload of 1500. Max ICMP echo payload length is only 1454 which is a result of 1500 - 18 (Ethernet Header) - 20 (IP Header) - 8 (ICMP Echo Request header) .

 

If you want to allow ping tests with larger payloads, increase the db variable to the appropriate value.