Secure Gre Tunnel (Gre-Over-Ipsec); Gre Tunnel Information - Cisco ROUTER-SDM-CD User Manual

Create Site to Site VPN

Secure GRE Tunnel (GRE-over-IPSec)

GRE Tunnel Information

Tunnel Source
Note
Details
Cisco Router and Security Device Manager 2.5 User's Guide
11-16
Generic routing encapsulation (GRE) is a tunneling protocol developed by Cisco
that can encapsulate a wide variety of protocol packet types inside IP tunnels,
creating a virtual point-to-point link to Cisco routers at remote points over an IP
internetwork. By connecting multiprotocol subnetworks in a single-protocol
backbone environment, IP tunneling using GRE allows network expansion across
a single-protocol backbone environment.
This wizard enables you to create a GRE tunnel with IPSec encryption. When you
create a GRE tunnel configuration, you also create an
endpoints of the tunnel.
General GRE tunnel information is provided in this screen.
Select the interface name or the IP address of the interface that the tunnel will use.
The IP address of the interface must be reachable from the other end of the tunnel;
therefore it must a a public, routable IP address. An error will be generated if you
enter an IP address that is not associated with any configured interface.
Cisco SDM lists interfaces with static IP addresses and interfaces configured as
unnumbered in the Interface list. Loopback interfaces are not included in the list.
Click to obtain details about the interface that you selected. The details window
shows any access rules, IPSec policies, NAT rules, or Inspection rules associated
with the interface. If a NAT rule has been applied to this interface that causes the
address to be unroutable, the tunnel will not operate properly. To examine any of
these rules in more detail, go to Additional Tasks/ACL Editor and examine the in
the Rules window.
Chapter 11 Site-to-Site VPN
IPSec rule that describes the
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