INE R&S ATC035 - IP Default-Gateway, IP Default-Network

Other Default Routing

• ip default-gateway
– Only when IP routing is off

• ip default-network
– Network flagged as default in routing advertisements
– Must be a classful network that is not directly connected


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IGRP不支援advertisement 0.0.0.0/0

* Asterisk

下 ip default-network 30.0.0.0 指令的路由器, 必須本身沒有這段網段, 還必須是 classfull network

Rack1R4# config t
Enter configuration commands, one per line.  End with CNTL/Z.
Rack1R4(config)# ip default-network 31.0.0.0
Rack1R4(config)# exit

Rack1R4#show ip route

Rack1R4#show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route

Gateway of last resort is 204.12.1.254 to network 31.0.0.0

 *   31.0.0.0/16 is subnetted, 4 subnets
R       31.3.0.0 [120/1] via 204.12.1.254, 00:00:13, FastEthernet0/0
R       31.2.0.0 [120/1] via 204.12.1.254, 00:00:13, FastEthernet0/0
R       31.1.0.0 [120/1] via 204.12.1.254, 00:00:13, FastEthernet0/0
R*      31.0.0.0 [120/1] via 204.12.1.254, 00:00:13, FastEthernet0/0
     30.0.0.0/16 is subnetted, 4 subnets
R       30.2.0.0 [120/1] via 204.12.1.254, 00:00:16, FastEthernet0/0
R       30.3.0.0 [120/1] via 204.12.1.254, 00:00:16, FastEthernet0/0
R       30.0.0.0 [120/1] via 204.12.1.254, 00:00:16, FastEthernet0/0
R       30.1.0.0 [120/1] via 204.12.1.254, 00:00:16, FastEthernet0/0
Rack1R4#

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Configuring a Gateway of Last Resort Using IP Commands
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094374.shtml

CCIE TO BE Blog - EIGRP - ip default-network command
http://ccietobe.blogspot.tw/2008/07/eigrp-ip-default-network-command.html

ip default-network與ip route的異同
http://www.killtest.com.tw/index.php/cisco/cisco-9/