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author | ae <ae@FreeBSD.org> | 2015-06-06 13:39:20 +0000 |
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committer | ae <ae@FreeBSD.org> | 2015-06-06 13:39:20 +0000 |
commit | fcae6374c46e27235434ab48a7b1cd1da69782dd (patch) | |
tree | c71d5b0ff1812244ff094426b4fe26e66b8b1bf1 | |
parent | 49fd76c05c1937d6c5bf27f823249d3605121fe0 (diff) | |
download | FreeBSD-src-fcae6374c46e27235434ab48a7b1cd1da69782dd.zip FreeBSD-src-fcae6374c46e27235434ab48a7b1cd1da69782dd.tar.gz |
MFC r283897:
Add example how to configure gre(4) tunnel with the same inner and
outer addresses using multiple FIBs.
-rw-r--r-- | share/man/man4/gre.4 | 40 |
1 files changed, 39 insertions, 1 deletions
diff --git a/share/man/man4/gre.4 b/share/man/man4/gre.4 index 6652bdf..15ef0ec 100644 --- a/share/man/man4/gre.4 +++ b/share/man/man4/gre.4 @@ -29,7 +29,7 @@ .\" .\" $FreeBSD$ .\" -.Dd November 7, 2014 +.Dd June 2, 2015 .Dt GRE 4 .Os .Sh NAME @@ -118,6 +118,44 @@ ifconfig greN inet 192.168.2.1 192.168.1.1 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 |