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26-8
User Guide for Cisco Security Manager 4.4
OL-28826-01
Chapter 26 GRE and DM VPNs
GRE and Dynamic GRE VPNs
Failover Cost
(OSPF or RIPv2 only.)
The cost of sending a packet on the secondary (failover) route interface.
You can enter a value in the range 1-65535 for OSPF (the default is
125), or in the range 1-15 for RIPv2 (the default is 2).
Filter Dynamic Updates on
Spokes
When selected, enables the creation of a redistribution list that filters
all dynamic routing updates on the spokes. This forces the spoke
devices to advertise (populate on the hub device) only their own
protected subnets and not other IP addresses.
Tunnel Parameters Tab
Tunnel IP Select the required option to specify the GRE or GRE Dynamic IP
tunnel interface IP address.
• Use Physical Interface—When selected, uses the private IP
address of the tunnel taken from the protected network.
• Use Subnet—When selected, uses the tunnel IP address taken from
an IP range. This is the default.
In the Subnet field, enter the private IP address including the
unique subnet mask (default is 1.1.1.0/24).
If you are also configuring a dial backup interface, enter its subnet
in the Dial Backup Subnet field provided (default is 1.1.2.0/24).
Note In most cases, when you use a subnet to specify a GRE tunnel
interface IP address, Security Manager creates a loopback
interface on the device which is used for the tunnel IP address.
If the device belongs to a VPN topology whose configurations
were discovered by Security Manager, and you configure an IP
address directly on the device’s GRE tunnel, Security Manager
keeps that configuration and does not create a loopback
interface on the device. However, a loopback is always
configured on a hub in a VPN topology; in a hub-and-spoke
VPN topology with multiple hubs, a loopback interface is also
configured on the spokes.
• Use Loopback Interface—When selected, uses the tunnel IP
address taken from an existing loopback interface. In the Role
field, enter the name of the interface role object that defines the
loopback interface name, or click Select to select it from a list or
to create a new object.
Note To view the new GRE tunnel or loopback interfaces in the
Router Interfaces page, you must rediscover the device
inventory details after successfully deploying the VPN to the
device.
Table 26-1 GRE Modes Page for GRE or GRE Dynamic IP VPNs (Continued)
Element Description