Cisco 500 Series, Configuration Manual

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9-3
Cisco Security Appliance Command Line Configuration Guide
OL-12172-03
Chapter 9 Configuring IP Routing
Configuring Static and Default Routes
Configuring a Default Static Route
A default route identifies the gateway IP address to which the security appliance sends all IP packets for
which it does not have a learned or static route. A default static route is simply a static route with
0.0.0.0/0 as the destination IP address. Routes that identify a specific destination take precedence over
the default route.
You can define up to three equal cost default route entries per device. Defining more than one equal cost
default route entry causes the traffic sent to the default route to be distributed among the specified
gateways. When defining more than one default route, you must specify the same interface for each
entry.
If you attempt to define more than three equal cost default routes, or if you attempt to define a default
route with a different interface than a previously defined default route, you receive the message
“ERROR: Cannot add route entry, possible conflict with existing routes.”
You can define a separate default route for tunneled traffic along with the standard default route. When
you create a default route with the
tunneled option, all traffic from a tunnel terminating on the security
appliance that cannot be routed using learned or static routes, is sent to this route. For traffic emerging
from a tunnel, this route overrides over any other configured or learned default routes.
The following restrictions apply to default routes with the tunneled option:
•
Do not enable unicast RPF ( ip verify reverse-path ) on the egress interface of tunneled route.
Enabling uRPF on the egress interface of a tunneled route causes the session to fail.
• Do not enable TCP intercept on the egress interface of the tunneled route. Doing so causes the
session to fail.
•
Do not use the VoIP inspection engines (CTIQBE, H.323, GTP, MGCP, RTSP, SIP, SKINNY), the
DNS inspect engine, or the DCE RPC inspection engine with tunneled routes. These inspection
engines ignore the tunneled route.
You cannot define more than one default route with the tunneled option; ECMP for tunneled traffic is
not supported.
To define the default route, enter the following command:
hostname(config)#
route
if_name
0.0.0.0 0.0.0.0
gateway_ip [ distance |
tunneled
]
Tip You can enter 0 0 instead of 0.0.0.0 0.0.0.0 for the destination network address and mask, for example:
hostname(config)# route outside 0 0 192.168.1 1
The following example shows a security appliance configured with three equal cost default routes and a
default route for tunneled traffic. Unencrypted traffic received by the security appliance for which there
is no static or learned route is distributed among the gateways with the IP addresses 192.168.2.1,
192.168.2.2, 192.168.2.3. Encrypted traffic receive by the security appliance for which there is no static
or learned route is passed to the gateway with the IP address 192.168.2.4.
hostname(config)# route outside 0 0 192.168.2.1
hostname(config)# route outside 0 0 192.168.2.2
hostname(config)# route outside 0 0 192.168.2.3
hostname(config)# route outside 0 0 192.168.2.4 tunneled