1008-dhcp6-reduce-maximum-initial-solicitation-delay-to-1.patch

From 5aa6eff182204b312007ac44dcfffdf4dc6b7428 Mon Sep 17 00:00:00 2001
From: Markus Boehme <markubo@amazon.com>
Date: Fri, 26 May 2023 16:21:11 +0200
Subject: [PATCH] dhcp6: reduce maximum initial solicitation delay to 100 ms

While RFC 3315 requires the initial solicitation delay to be randomly
chosen between 0 and 1000 ms to prevent a thundering herd of synchronized
clients during mass reboots, not all clients (e.g. systemd-networkd) follow
this. Reduce the maximum delay to 100 ms which, together with natural
jitter during boot, still seems plenty and cuts down the time to lease.

Note that the more recent RFC 8415 softened its stance a bit. The
initial solicitation delay "SHOULD" be followed, i.e. is recommended but
not required.

Signed-off-by: Markus Boehme <markubo@amazon.com>
---
 src/dhcp6/protocol.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/dhcp6/protocol.h b/src/dhcp6/protocol.h
index cd917ba..5f40902 100644
--- a/src/dhcp6/protocol.h
+++ b/src/dhcp6/protocol.h
@@ -119,7 +119,7 @@ enum NI_DHCP6_MSG_TYPE {
  *      Parameter		  Value    Description
  * ---------------------------------------------------------------------------
  */
-#define	NI_DHCP6_SOL_MAX_DELAY	   1000	/* Max delay of first Solicit  */
+#define	NI_DHCP6_SOL_MAX_DELAY	    100	/* Max delay of first Solicit  */
 #define NI_DHCP6_SOL_TIMEOUT	   1000	/* Initial Solicit timeout     */
 #define NI_DHCP6_SOL_MAX_RT	3600000	/* Max Solicit timeout value   */
 #define NI_DHCP6_REQ_TIMEOUT	   1000	/* Initial Request timeout     */
-- 
2.40.1