Date: Tue, 2 Jun 2015 00:47:39 +0000 (UTC) From: "Andrey V. Elsukov" <ae@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r283897 - head/share/man/man4 Message-ID: <201506020047.t520ldXV031121@svn.freebsd.org>
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Author: ae Date: Tue Jun 2 00:47:38 2015 New Revision: 283897 URL: https://svnweb.freebsd.org/changeset/base/283897 Log: Add example howto configure gre(4) tunnel with the same inner and outer addresses using multiple FIBs. X-MFC after: r282809 Modified: head/share/man/man4/gre.4 Modified: head/share/man/man4/gre.4 ============================================================================== --- head/share/man/man4/gre.4 Mon Jun 1 21:10:47 2015 (r283896) +++ head/share/man/man4/gre.4 Tue Jun 2 00:47:38 2015 (r283897) @@ -29,7 +29,7 @@ .\" .\" $FreeBSD$ .\" -.Dd November 7, 2014 +.Dd June 2, 2015 .Dt GRE 4 .Os .Sh NAME @@ -117,6 +117,44 @@ ifconfig greN inet 192.168.2.1 192.168.1 ifconfig greN inet tunnel B A route add -net 192.168.1 -netmask 255.255.255.0 192.168.1.1 .Ed +.Pp +In case when internal and external IP addresses are the same, +different routing tables (FIB) should be used. +The default FIB will be applied to IP packets before GRE encapsulation. +After encapsulation GRE interface should set different FIB number to +outgoing packet. +Then different FIB will be applied to such encapsulated packets. +According to this FIB packet should be routed to tunnel endpoint. +.Bd -literal +Host X -- Host A (198.51.100.1) ---tunnel--- Cisco D (203.0.113.1) -- Host E + \\ / + \\ / + +----- Host B ----- Host C -----+ + (198.51.100.254) +.Ed +.Pp +On Host A (FreeBSD): +.Pp +First of multiple FIBs should be configured via loader.conf: +.Bd -literal -offset indent +net.fibs=2 +net.add_addr_allfibs=0 +.Ed +.Pp +Then routes to the gateway and remote tunnel endpoint via this gateway +should be added to the second FIB: +.Bd -literal -offset indent +route add -net 198.51.100.0 -netmask 255.255.255.0 -fib 1 -iface em0 +route add -host 203.0.113.1 -fib 1 198.51.100.254 +.Ed +.Pp +And GRE tunnel should be configured to change FIB for encapsulated packets: +.Bd -literal -offset indent +ifconfig greN create +ifconfig greN inet 198.51.100.1 203.0.113.1 +ifconfig greN inet tunnel 198.51.100.1 203.0.113.1 tunnelfib 1 +.Ed +.Pp .Sh NOTES The MTU of .Nm
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