igmp: Document sysctl force_igmp_version

There is some difference between force_igmp_version and force_mld_version.
Add document to make users aware of this.

Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Hangbin Liu 2016-11-07 14:51:23 +08:00 committed by David S. Miller
parent 3f9b9770b4
commit 1af92836e5

View file

@ -967,6 +967,21 @@ igmp_qrv - INTEGER
Default: 2 (as specified by RFC2236 8.1)
Minimum: 1 (as specified by RFC6636 4.5)
force_igmp_version - INTEGER
0 - (default) No enforcement of a IGMP version, IGMPv1/v2 fallback
allowed. Will back to IGMPv3 mode again if all IGMPv1/v2 Querier
Present timer expires.
1 - Enforce to use IGMP version 1. Will also reply IGMPv1 report if
receive IGMPv2/v3 query.
2 - Enforce to use IGMP version 2. Will fallback to IGMPv1 if receive
IGMPv1 query message. Will reply report if receive IGMPv3 query.
3 - Enforce to use IGMP version 3. The same react with default 0.
Note: this is not the same with force_mld_version because IGMPv3 RFC3376
Security Considerations does not have clear description that we could
ignore other version messages completely as MLDv2 RFC3810. So make
this value as default 0 is recommended.
conf/interface/* changes special settings per interface (where
"interface" is the name of your network interface)