Cisco CISCO876-SEC-I-K9 Configuration Guide - Page 123

Dial Backup Feature Limitations

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Chapter 13 Configuring Dial Backup and Remote Management Dial Backup Feature Limitations Step 5 Command ip route prefix mask {ip-address | interface-type interface-number [ip-address]} [distance] Example: Router(config)# ip route 0.0.0.0 0.0.0.0 192.168.2.2 150 Router(config)# Purpose Assigns the lower routing administrative distance value for the backup interface route. 192.168.2.2 is the peer IP address of the backup interface. Step 6 dialerwatch-list group-number {ip ip-address address-mask | delay route-check initial seconds} Example: Router(config)# dialer watch-list 2 ip 22.0.0.2 255.255.255.255 Router(config)# Assigns an IP address to the watch list. If the connection on the primary interface is lost and the IP address is unavailable on the router, the dial-out feature on the backup interface is triggered. 22.0.0.2 is the peer IP address of the primary interface. Dial Backup Feature Limitations The following limitations exist for the dial backup feature: • Bridging is not supported over console or auxiliary port backup interfaces. • For the Cisco 851 router, only dial-in capability is supported. • Dial backup support on the Cisco 871 router is limited because the Ethernet WAN interface is always up, even when ISP connectivity is down on the other side of the modem connected to the Cisco 871 router. The router must be in a PPPoE environment with the dialer watch feature running. The IP addresses of the peer must be specified in the dialer watch and the static route commands to enable dial backup when the primary line goes down. Table 13-1 summarizes dial backup support and limitations for the Cisco 800 series access routers. Table 13-1 Dial Backup Feature Support and Limitations Summary WAN Encapsulation Type Cisco 851 or 871 PPPoE Dial Backup Possible? Yes Dial Backup Method Dialer watch Normal IP in cable No modem scenario Dialer watch Limitations Bridging is not supported across a slow interface, for example, an auxiliary port. The peer IP address of the ISP is needed to configure the dialerwatch command and the IP static route. The IP addresses of the peers are needed for dialer watch to work properly. If a lease time obtained by DHCP is not set short enough (1 or 2 minutes), dial backup will not be supported. OL-5332-01 Cisco 850 Series and Cisco 870 Series Access Routers Software Configuration Guide 13-5

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13-5
Cisco 850 Series and Cisco 870 Series Access Routers Software Configuration Guide
OL-5332-01
Chapter 13
Configuring Dial Backup and Remote Management
Dial Backup Feature Limitations
Dial Backup Feature Limitations
The following limitations exist for the dial backup feature:
•
Bridging is not supported over console or auxiliary port backup interfaces.
•
For the Cisco 851 router, only dial-in capability is supported.
•
Dial backup support on the Cisco 871 router is limited because the Ethernet WAN interface is always
up, even when ISP connectivity is down on the other side of the modem connected to the Cisco 871
router. The router must be in a PPPoE environment with the dialer watch feature running. The IP
addresses of the peer must be specified in the dialer watch and the static route commands to enable
dial backup when the primary line goes down.
Table 13-1
summarizes dial backup support and limitations for the Cisco 800 series access routers.
Step 5
ip route
prefix mask
{
ip-address
|
interface-type
interface-number
[
ip-address
]} [
distance
]
Example:
Router(config)#
ip route 0.0.0.0 0.0.0.0
192.168.2.2 150
Router(config)#
Assigns the lower routing administrative distance
value for the backup interface route. 192.168.2.2
is the peer IP address of the backup interface.
Step 6
dialerwatch-list
group-number
{
ip
ip-address
address-mask
|
delay route-check initial
seconds
}
Example:
Router(config)#
dialer watch-list 2 ip
22.0.0.2 255.255.255.255
Router(config)#
Assigns an IP address to the watch list.
If the connection on the primary interface is lost
and the IP address is unavailable on the router, the
dial-out feature on the backup interface is
triggered. 22.0.0.2 is the peer IP address of the
primary interface.
Command
Purpose
Table 13-1
Dial Backup Feature Support and Limitations Summary
WAN Encapsulation
Type
Dial Backup
Possible?
Dial Backup Method
Limitations
Cisco 851 or 871
PPPoE
Yes
Dialer watch
Bridging is not supported across a slow interface, for
example, an auxiliary port. The peer IP address of the ISP is
needed to configure the
dialerwatch
command and the IP
static route.
Normal IP in cable
modem scenario
No
Dialer watch
The IP addresses of the peers are needed for dialer watch to
work properly. If a lease time obtained by DHCP is not set
short enough (1 or 2 minutes), dial backup will not be
supported.