Commit 41958a2117 for frr

commit 41958a211759647a36be09556e0621cbe3d3a04c
Author: Yoann Lopez <yoann.lopez@gmail.com>
Date:   Mon Nov 2 14:12:29 2026 +0100

    doc: document disabling periodic CSNPs on p2p circuits

    Describe the new interface command, its effect on point-to-point and
    broadcast circuits, and the warnings it prints.

    Assisted-by: Claude <noreply@anthropic.com>
    Signed-off-by: Yoann Lopez <yoann.lopez@gmail.com>

diff --git a/doc/user/isisd.rst b/doc/user/isisd.rst
index 9a0b69c280..5fae14f1ad 100644
--- a/doc/user/isisd.rst
+++ b/doc/user/isisd.rst
@@ -292,6 +292,18 @@ sessions.
    Enable or disable :rfc:`5303` Three-Way Handshake for P2P adjacencies.
    Three-Way Handshake is enabled by default.

+.. clicmd:: isis periodic-csnp
+
+   Enable or disable periodic CSNPs on a point-to-point circuit. When
+   disabled, a complete set of CSNPs is sent only when an adjacency comes
+   up, as described in :rfc:`5303`, instead of every ``isis csnp-interval``.
+   This saves bandwidth, at the cost of the periodic database check.
+   Periodic CSNPs are enabled by default. While they are disabled,
+   ``isis csnp-interval`` is not used on point-to-point circuits, and setting
+   a CSNP interval other than the default prints a warning. On a broadcast
+   circuit the DIS keeps sending periodic CSNPs: the setting has no effect
+   there, and setting it prints a warning.
+
 .. clicmd:: isis ipv4-over-ipv6-nexthop

    Route IPv4 over this interface when it has no usable IPv4 nexthop, such