[PATCH v2] rtnetlink.7: Document metrics attributes (RTAX_*).
From: Guillaume Nault <hidden>
Date: 2025-10-08 19:12:33
Subsystem:
the rest · Maintainer:
Linus Torvalds
Add a brief explanation of the RTAX attributes that can be used in
RTA_METRICS.
Signed-off-by: Guillaume Nault <redacted>
---
v2: * Reset indentation right after the RTAX_* table (Alejandro).
* Use .RS/.RE instead of .in (Alejandro).
man/man7/rtnetlink.7 | 49 +++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 48 insertions(+), 1 deletion(-)
diff --git a/man/man7/rtnetlink.7 b/man/man7/rtnetlink.7
index 78f35b47e..36b9642af 100644
--- a/man/man7/rtnetlink.7
+++ b/man/man7/rtnetlink.7@@ -343,7 +343,11 @@ RTA_OIF:int:Output interface index RTA_GATEWAY:protocol address:The gateway of the route RTA_PRIORITY:int:Priority of route RTA_PREFSRC:protocol address:Preferred source address -RTA_METRICS:int:Route metric +RTA_METRICS::T{ +Route metrics +.br +(see below). +T} RTA_MULTIPATH::T{ Multipath nexthop data .br
@@ -386,6 +390,49 @@ routes (in seconds) T} .TE .IP +.B RTA_METRICS +contains an array of +.I struct rtattr +with their corresponding attributes: +.RS +.IP +.TS +tab(:); +c s s +lb l l. +Attributes +rta_type:Value type:Description +_ +RTAX_UNSPEC:-:unspecified +RTAX_LOCK:__u32:Bit field indicating which RTAX_* attributes are locked +RTAX_MTU:__u32:Maximum Transmission Unit for this route +RTAX_WINDOW:__u32:Maximum size of the receive window for this route +RTAX_RTT:__u32:Estimated round-trip time for this route +RTAX_RTTVAR:__u32:Estimated round-trip time variation for this route +RTAX_SSTHRESH:__u32:Slow start threshold to use for this route +RTAX_CWND:__u32:Maximum size of the congestion window for this route +RTAX_ADVMSS:__u32:Maximum Segment Size to advertise for this route +RTAX_REORDERING:__u32:Initial reordering level of packets for this route +RTAX_HOPLIMIT:__u32:Hop limit (TTL) to use for this route +RTAX_INITCWND:__u32:Initial congestion window to use for this route +RTAX_FEATURES:__u32:Features to enable for this route specifically +RTAX_RTO_MIN:__u32:Minimum Retransmission TimeOut to use for this route +RTAX_INITRWND:__u32:Initial size of the receive window for this route +RTAX_QUICKACK:__u32:Use quick ack for this route +RTAX_CC_ALGO:asciiz string:Congestion Control algorithm to use for this route +RTAX_FASTOPEN_NO_COOKIE:__u32:Allow TCP Fast Open without cookie +.TE +.RE +.IP +Metrics that are locked with +.B RTAX_LOCK +take precedence over the values normally used by the kernel +(computed or assigned by a sysctl or setsockopt(2)). +Therefore, some metrics, like +.BR RTAX_RTO_MIN , +have no effect unless their bit is set in +.BR RTAX_LOCK . +.IP .B RTA_MULTIPATH contains several packed instances of .I struct rtnexthop
--
2.47.3