This article explains the reason behind the commit warning "ICMP protocol is not recommended for the inet6 family" generated after upgrading to junOS version 22.2 or higher.

While trying to commit any configuration on the firewall, below given commit warnings are generated :

user@srx# show | compare
[edit interfaces st0 unit 3]
+ disable;
[edit]
user@srx# commit confirmed 
warning: 'icmp' protocol is not recommended for 'inet6' family.
warning: 'icmp' protocol is not recommended for 'inet6' family.
warning: 'icmp' protocol is not recommended for 'inet6' family.

This warning is generated after upgrading to junOS version 22.2 or higher, if the device has ICMP inet6 filters configured incorrectly with next-header icmp instead of icmp6, as shown below:

user@srx>show configuration | display set | match icmp
user@srx>set firewall family inet6 filter ipv6 term icmpv6 from next-header icmp

In family inet6 filters icmp6 must be used instead of icmp protocol, as icmp is used for ipv4 only. In junoS version 22.2 or higher, code is performing additional checks in IP firewall filters hence the commit warning will show up. This can be fixed by correcting the configuration as shown below:

user@srx#set firewall family inet6 filter ipv6 term icmpv6 from next-header icmp6
user@srx#commit
configuration check succeeds
commit complete