Re: [PATCH] gre: copy ToS/DiffServ bits to outer IP header

From: Patrick McHardy
Date: Mon Jun 29 2009 - 09:49:15 EST


Andreas Jaggi wrote:
When tunneling IP traffic with GRE this patch makes it possible to export the ToS/DiffServ information to the outer IP header.
This is particularly useful in a scenario with ESP/AH where the inner IP header is encrypted but the packet priority/DiffServ information
should still be respected by the transporting routers (for example in an MPLS backbone network).

The feature is disabled by default and can be enabled on a per-interface basis (/proc/sys/net/ipv4/conf/ethX/gre_copy_tos).

Also does this bring Linux back in the game, as JunOS/IOS provide this for quite some time:
http://www.cisco.com/en/US/docs/ios/11_3/feature/guide/greqos.html
http://www.juniper.net/techpubs/software/junos/junos94/swconfig-services/configuring-a-gre-tunnel-to-copy-tos-bits-to-the-outer-ip-header.html


Signed-off-by: Andreas Jaggi <aj@xxxxxxx>

diff -urN vanilla-linux-2.6.29.4/include/linux/sysctl.h gre-copy-tos/include/linux/sysctl.h
--- vanilla-linux-2.6.29.4/include/linux/sysctl.h 2009-05-19 01:52:34.000000000 +0200
+++ gre-copy-tos/include/linux/sysctl.h 2009-06-29 14:23:07.000000000 +0200
@@ -490,6 +490,7 @@
NET_IPV4_CONF_ARP_IGNORE=19,
NET_IPV4_CONF_PROMOTE_SECONDARIES=20,
NET_IPV4_CONF_ARP_ACCEPT=21,
+ NET_IPV4_CONF_GRE_COPY_TOS=22,

Please add this to the rtnl_link interface instead of using
sysctls.
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