最近我在调试一个网络,该网络使用一对二方式. 其中一个远端A与Internet互连,中心点与另外一个远端B通过该远端A连入Internet. 并且三点之间内部互通.
现三地之间用三台Cisco互连,能正常工作. 但是现需要备份中心点与两个远端之间的通信线路.
计划采用ISDN拨号备份.
ISDN Configuration Example - IP
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Sample Configuration for C2503
C2503#wr t
######
Current configuration:
!
version 10.2
!
hostname C2503
!
enable password test
!
username C4000 password cisco (See username explanation in the followi
ng
section.)
isdn switch-type basic-dms100
!
interface Ethernet0
ip address 172.16.10.1 255.255.255.0
!
interface Serial0
no ip address
shutdown
!
interface Serial1
no ip address
shutdown
!
interface BRI0
ip address 172.16.20.1 255.255.255.0
encapsulation ppp
bandwidth 56
dialer idle-timeout 300
dialer map ip 172.16.20.2 name C4000 speed 56 broadcast 14155551234
dialer map ip 172.16.20.2 name C4000 speed 56 broadcast 14155556789
dialer hold-queue 5
dialer load-threshold 100
dialer-group 1
isdn spid1 408555432101 5554321
isdn spid2 408555987601 5559876
ppp authentication chap
!
router igrp 1
network 172.16.0.0
!
ip route 192.168.24.0 255.255.255.0 172.16.20.2
access-list 100 deny ip 0.0.0.0 255.255.255.255 255.255.255.255 0.0.0.
0
access-list 100 permit ip 0.0.0.0 255.255.255.255 0.0.0.0 255.255.255.
255
!
!
dialer-list 1 list 100
!
line con 0
line aux 0
line vty 0 4
password test
login
!
end
Explanation of C2503 Configuration
C2503#wr t
######
Current configuration:
!
version 10.2
!
hostname C2503
!
enable password test
!
username C4000 password cisco
The username "C4000" is the hostname of the remote router and is used by the dialer map command below. The username is case sensitive and must match the remote router''s hostname exactly. The password, which is used by the CHAP authentication process, is case sensitive and must match the remote router''s password exactly.
Note: To avoid confusion, the unencrypted form of the password cisco is shown in this sample configuration. In the actual configuration, thepassword would appear in its encrypted form: 7 13061E010803, where 7denotes the encryption type and 3061E010803 is the encrypted form of the password cisco. When entering or making changes to the username command, always type the password in its unencrypted form and do not enter the encryption type (7). It is set automatically.
isdn switch-type basic-dms100
The ISDN switch type must match your carrier''s equipment. If you change the switch-type, you must reload the router for the new switch type to take effect.
interface Ethernet0
ip address 172.16.10.1 255.255.255.0
interface Serial0
no ip address
shutdown
!
interface Serial1
no ip address
shutdown
!
interface BRI0
ip address 172.16.20.1 255.255.255.0
encapsulation ppp
PPP encapsulation is recommended over HDLC in order to allow the use of CHAP authentication.
bandwidth 56
The default bandwidth setting for a BRI interface is 64k. If you configured your dialer map statements with the speed 56 option, you should include the bandwidth statement.
Note: This command does not control the speed of your ISDN line. It sets the correct reference point for the BRI port''s show interface statistics, for the dialer load-threshold command, and for IGRP/EIGRP routing metrics.
dialer idle-timeout 300
This command sets the number of seconds the ISDN connection will remain open if no interesting traffic is being routed. The timer is reset each time an interesting packet is forwarded.
dialer map ip 172.16.20.2 name C4000 speed 56 broadcast 14155551234
dialer map ip 172.16.20.2 name C4000 speed 56 broadcast 14155556789
The dialer map command is used with CHAP authentication to place the initial call to the remote router when interesting traffic is forwardedto the BRI interface. Once the connection is active, the dialer idle-timeout command determines how long it will remain active. A dialer map statement is required for each ISDN phone number that will be called . Be aware though, that two dialer map statements pointing to the same location might activate both B channels when you may only want to useone channel.
Note: The command parameters for this example are:
172.16.20.2 = the IP address of the remote router''s BRI interface. Todetermine this address, type show interface bri 0 at the remote router''s console prompt.
name C4000 = the hostname of the remote router. The name is case sensitive and should match the name configured for the username command above.
speed 56 = sets the dialer speed to 56k for ISDN circuits that are not 64k end-to-end, and should be included in both routers'' dialer map statements. Most installations in North America must be configured for 56K.
broadcast = allows the forwarding of broadcast packets. Unless broadcast packets are specified as interesting packets by the dialer-list command, they will only be forwarded when the ISDN link is active.
14155551234
14155556789 = the remote router''s ISDN telephone numbers.
dialer hold-queue 5
This command allows interesting packets to be queued until the ISDN connection is established. In this example, five interesting packets will be queued.
dialer load-threshold 100
This command is used to configure bandwidth on demand by setting the maximum load before the dialer places another call through the second B channel. The load is the calculated weighted average load value for the interface, where 1 is unloaded and 255 is fully loaded. The actual load value you should configure depends on the characteristics of your particular network. In this example, the second B channel will be activated when the load reaches 39% of maximum utilization, which is 100 divided by 255.
