give egre an example

nvgre had an example of joining nvgre networks together over the
internet with egre. this takes it away and reworks it for an egre
example.

while here, get rid of the hostnames in the shell prompts so things
are more consistent, which jmc and i discussed.

1 files changed, 86 insertions, 57 deletions

diff --git a/share/man/man4/gre.4 b/share/man/man4/gre.4
index 43d42192622..fc46c959ea4 100644
--- a/share/man/man4/gre.4
+++ b/share/man/man4/gre.4
@@ -1,4 +1,4 @@
-.\" $OpenBSD: gre.4,v 1.66 2018/02/23 09:50:30 jmc Exp $
+.\" $OpenBSD: gre.4,v 1.67 2018/02/25 01:16:12 dlg Exp $
 .\" $NetBSD: gre.4,v 1.10 1999/12/22 14:55:49 kleink Exp $
 .\"
 .\" Copyright 1998 (c) The NetBSD Foundation, Inc.
@@ -28,7 +28,7 @@
 .\" ARISING IN ANY WAY  OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 .\" POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd $Mdocdate: February 23 2018 $
+.Dd $Mdocdate: February 25 2018 $
 .Dt GRE 4
 .Os
 .Sh NAME
@@ -414,6 +414,76 @@ In most cases the following should work:
 .Bd -literal -offset indent
 pass quick on gre proto gre no state
 .Ed
+.Ss Point-to-Point Ethernet over GRE tunnel interfaces (egre)
+.Nm egre
+can be used to carry Ethernet traffic between two endpoints over
+an IP network, including the public internet.
+This can also be achieved using
+.Xr etherip 4 ,
+but
+.Nm egre
+offers the ability to carry different Ethernet networks between the
+same endpoints by using virtual network identifiers to distinguish
+between them.
+.Pp
+For example, a pair of routers separated by the internet could
+bridge several Ethernet networks using
+.Nm egre
+and
+.Xr bridge 4 .
+.Pp
+In this example the first router has a public IP of 192.0.2.1, and
+the second router has 203.0.113.2.
+They are connecting the Ethernet networks on two
+.Xr vlan 4
+interfaces over the internet.
+A separate
+.Nm egre
+tunnel is created for each VLAN and given different virtual network
+identifiers so the routers can tell which network the encapsulated
+traffic is for.
+The
+.Nm egre
+interfaces are explicitley configured to provide the same MTU as the
+.Xr vlan 4
+interfaces (1500 bytes) with fragmentation enabled so they can be
+carried over the internet, which has the same or lower MTU.
+.Pp
+At the first site:
+.Bd -literal -offset indent
+# ifconfig vlan0 vnetid 100
+# ifconfig egre0 create
+# ifconfig egre0 tunnel 192.0.2.1 203.0.113.2
+# ifconfig egre0 vnetid 100
+# ifconfig egre0 mtu 1500 -tunneldf
+# ifconfig egre0 up
+# ifconfig bridge0 add vlan0 add egre0 up
+# ifconfig vlan1 vnetid 200
+# ifconfig egre1 create
+# ifconfig egre1 tunnel 192.0.2.1 203.0.113.2
+# ifconfig egre1 vnetid 200
+# ifconfig egre1 mtu 1500 -tunneldf
+# ifconfig egre1 up
+# ifconfig bridge1 add vlan1 add egre1 up
+.Ed
+.Pp
+At the second site:
+.Bd -literal -offset indent
+# ifconfig vlan0 vnetid 100
+# ifconfig egre0 create
+# ifconfig egre0 tunnel 203.0.113.2 192.0.2.1
+# ifconfig egre0 vnetid 100
+# ifconfig egre0 mtu 1500 -tunneldf
+# ifconfig egre0 up
+# ifconfig bridge0 add vlan0 add egre0 up
+# ifconfig vlan1 vnetid 200
+# ifconfig egre1 create
+# ifconfig egre1 tunnel 203.0.113.2 192.0.2.1
+# ifconfig egre1 vnetid 200
+# ifconfig egre1 mtu 1500 -tunneldf
+# ifconfig egre1 up
+# ifconfig bridge1 add vlan1 add egre1 up
+.Ed
 .Ss Network Virtualization Using GRE interfaces (nvgre)
 NVGRE can be used to build a distinct logical Ethernet network
 on top of another network.
@@ -487,26 +557,26 @@ on each host, and em0 has had the MTU raised:
 .Pp
 On physical host 1:
 .Bd -literal -offset indent
-hv0# ifconfig em0 inet 100.64.10.10/24
-hv0# ifconfig nvgre1 parent em0 tunnel 100.64.10.10 239.1.1.111
-hv0# ifconfig nvgre1 vnetid 10011
-hv0# ifconfig bridge1 add nvgre1 add tap0 up
+# ifconfig em0 inet 100.64.10.10/24
+# ifconfig nvgre1 parent em0 tunnel 100.64.10.10 239.1.1.111
+# ifconfig nvgre1 vnetid 10011
+# ifconfig bridge1 add nvgre1 add tap0 up
 .Ed
 .Pp
 On physical host 2:
 .Bd -literal -offset indent
-hv1# ifconfig em0 inet 100.64.10.11/24
-hv1# ifconfig nvgre1 parent em0 tunnel 100.64.10.11 239.1.1.111
-hv1# ifconfig nvgre1 vnetid 10011
-hv1# ifconfig bridge1 add nvgre1 add tap0 up
+# ifconfig em0 inet 100.64.10.11/24
+# ifconfig nvgre1 parent em0 tunnel 100.64.10.11 239.1.1.111
+# ifconfig nvgre1 vnetid 10011
+# ifconfig bridge1 add nvgre1 add tap0 up
 .Ed
 .Pp
 On physical host 3:
 .Bd -literal -offset indent
-hv2# ifconfig em0 inet 100.64.10.12/24
-hv2# ifconfig nvgre1 parent em0 tunnel 100.64.10.12 239.1.1.111
-hv2# ifconfig nvgre1 vnetid 10011
-hv2# ifconfig bridge1 add nvgre1 add tap0 up
+# ifconfig em0 inet 100.64.10.12/24
+# ifconfig nvgre1 parent em0 tunnel 100.64.10.12 239.1.1.111
+# ifconfig nvgre1 vnetid 10011
+# ifconfig bridge1 add nvgre1 add tap0 up
 .Ed
 .Pp
 Being able to carry working multicast and jumbo frames over the
@@ -516,51 +586,10 @@ to extended Ethernet VPNs between different sites.
 and
 .Nm egre
 can be bridged together to provide such connectivity.
-.Pp
-In this example the NVE device at the first site has a public IP
-of 192.0.2.1, and uses 100.64.10.0/24 for the NVGRE underlay network.
-The second site has a public IP 203.0.113.2, and uses 100.64.11.0/24 for
-the NVGRE underlay.
-.Nm egre
-is explicitly configured to provide the same MTU as the
-.Nm nvgre
-interfaces, but allows the encapsulated frames to be fragmented.
-Multiple
+See the
 .Nm egre
-interfaces are used to carry traffic for two different NVGRE networks,
-so each interface must configure distinct virtual network identifiers.
+section for an example.
 .Pp
-At the first site:
-.Bd -literal -offset indent
-nve0# ifconfig nvgre0 parent em0 tunnel 100.64.10.1 239.1.1.100
-nve0# ifconfig nvgre0 vnetid 10000
-nve0# ifconfig egre0 create
-nve0# ifconfig egre0 tunnel 192.0.2.1 203.0.113.2
-nve0# ifconfig egre0 vnetid 10000 vnetflowid -tunneldf
-nve0# ifconfig bridge0 add nvgre0 add egre0 up
-nve0# ifconfig nvgre1 parent em0 tunnel 100.64.10.1 239.1.1.111
-nve0# ifconfig nvgre1 vnetid 10011
-nve0# ifconfig egre1 create
-nve0# ifconfig egre1 tunnel 192.0.2.1 203.0.113.2
-nve0# ifconfig egre1 vnetid 10011 vnetflowid -tunneldf
-nve0# ifconfig bridge0 add nvgre0 add egre0 up
-.Ed
-.Pp
-At the second site:
-.Bd -literal -offset indent
-nve1# ifconfig nvgre0 parent em0 tunnel 100.64.11.1 239.1.1.100
-nve1# ifconfig nvgre0 vnetid 10000
-nve1# ifconfig egre0 create
-nve1# ifconfig egre0 tunnel 203.0.113.2 192.0.2.1
-nve1# ifconfig egre0 vnetid 10000 vnetflowid -tunneldf
-nve1# ifconfig bridge0 add nvgre0 add egre0 up
-nve1# ifconfig nvgre1 parent em0 tunnel 100.64.11.1 239.1.1.111
-nve1# ifconfig nvgre1 vnetid 10011
-nve1# ifconfig egre1 create
-nve1# ifconfig egre1 tunnel 203.0.113.2 192.0.2.1
-nve1# ifconfig egre1 vnetid 10011 vnetflowid -tunneldf
-nve1# ifconfig bridge1 add nvgre1 add egre1 up
-.Ed
 .Sh SEE ALSO
 .Xr inet 4 ,
 .Xr ip 4 ,