Specifications

2-15
Cisco AS5x00 Case Study for Basic IP Modem Services
11/24/1999
Section 2 Commissioning the Cisco AS5300 Hardware
Configuring Cisco IOS Basics
2.4 Configuring the Loopback Interfaces, Ethernet Interface, and IP Route
To commission a basic dial access service:

Create two loopback interfaces

Bring up the ethernet interface

Add an IP route to the default gateway
Step 1
Assign the IP addresses, and create an IP route to the default gateway:
!
interface Loopback0
ip address 172.22.99.1 255.255.255.255
!
interface Loopback1
ip address 172.22.90.1 255.255.255.0
!
interface Ethernet0
ip address 172.22.66.23 255.255.255.0
!
ip route 0.0.0.0 0.0.0.0 172.22.66.1
!
In this example:

Interface loopback 0—Identifies with a unique and stable IP address. One unique IP address from
a common block of addresses is assigned to each device in the IP network. This technique makes
security-filtering easy for the network operations center (NOC). One class C subnet used for device
identification can support 254 distinct devices with unique loopback addresses.

Interface loopback 1—Hosts a pool of IP addresses for the remote nodes. In this way, one route is
summarized and propagated to the backbone instead of 254 routes.
Step 2
Verify that the Ethernet interface is up. Ping the default gateway to verify this.
5300-NAS#ping 172.22.66.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.22.66.1, timeout is 2 seconds:
.!!!!
Success rate is 80 percent (4/5), round-trip min/avg/max = 1/1/1 ms
5300-NAS#
This step verifies that you have IP connectivity with another device on the subnet. If the ping succeeds
to the default gateway, try pinging the DNS server in your backbone. Make sure the backbone routers
are configured to get to the access server; otherwise, the ping will not work. Configure the backbone
routers to support the routes to the networks you are using.
Note
An 80% ping-success rate is normal for the first time you ping an external device.
The NAS does not yet have an ARP entry (address resolution protocol) for the
external device. A 100% success rate is achieved the next time you ping the
device.