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From: Stefano Brivio <sbrivio@redhat.com>
To: passt-dev@passt.top
Subject: [PATCH] passt.1: Fix description of --mtu option
Date: Wed, 15 Mar 2023 10:13:50 +0100	[thread overview]
Message-ID: <20230315091350.3767103-1-sbrivio@redhat.com> (raw)

By default, 65520 bytes are advertised, and zero disables DHCP and
NDP options.

Fixes: ec2b58ea4dc4 ("conf, dhcp, ndp: Fix message about default MTU, make NDP consistent")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
---
 passt.1 | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/passt.1 b/passt.1
index 6136fa5..4c90634 100644
--- a/passt.1
+++ b/passt.1
@@ -135,8 +135,10 @@ background (if configured to do so).
 
 .TP
 .BR \-m ", " \-\-mtu " " \fImtu
-Assign \fImtu\fR via DHCP (option 26) and NDP (option type 5).
-By default, no MTU options will be sent.
+Assign \fImtu\fR via DHCP (option 26) and NDP (option type 5). A zero value
+disables assignment.
+By default, the advertised MTU is 65520 bytes, that is, the maximum 802.3 MTU
+minus the length of a 802.3 header, rounded to 32 bits (IPv4 words).
 
 .TP
 .BR \-a ", " \-\-address " " \fIaddr
-- 
@@ -135,8 +135,10 @@ background (if configured to do so).
 
 .TP
 .BR \-m ", " \-\-mtu " " \fImtu
-Assign \fImtu\fR via DHCP (option 26) and NDP (option type 5).
-By default, no MTU options will be sent.
+Assign \fImtu\fR via DHCP (option 26) and NDP (option type 5). A zero value
+disables assignment.
+By default, the advertised MTU is 65520 bytes, that is, the maximum 802.3 MTU
+minus the length of a 802.3 header, rounded to 32 bits (IPv4 words).
 
 .TP
 .BR \-a ", " \-\-address " " \fIaddr
-- 
2.39.2


             reply	other threads:[~2023-03-15  9:13 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-15  9:13 Stefano Brivio [this message]
2023-03-18  2:03 ` [PATCH] passt.1: Fix description of --mtu option David Gibson

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