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Default Networks display in routing tables

Any Experts to explain the meaning of Default Networks in the routing tables below:

I see "*"  next to C* and D*
what does that mean ?

Thank you

R2#sh ip route connected 
Codes: L - local, 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, + - replicated route

Gateway of last resort is not set

      192.168.12.0/24 is variably subnetted, 2 subnets, 2 masks
C        192.168.12.0/24 is directly connected, FastEthernet1/0
L        192.168.12.2/32 is directly connected, FastEthernet1/0
 *    192.168.23.0/24 is variably subnetted, 2 subnets, 2 masks
C*       192.168.23.0/24 is directly connected, FastEthernet0/0
L        192.168.23.2/32 is directly connected, FastEthernet0/0
R2#

Open in new window


R1#sh ip route eigrp
Codes: L - local, 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, + - replicated route

Gateway of last resort is not set

D*    192.168.23.0/24 [90/30720] via 192.168.12.2, 00:01:47, FastEthernet0/0
R1#

Open in new window



R1#sh run
Building configuration...

Current configuration : 1213 bytes
!
upgrade fpd auto
version 15.0
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R1
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
!
!
!
ip source-route
no ip icmp rate-limit unreachable
ip cef
!
!        
!
!
no ip domain lookup
no ipv6 cef
!
multilink bundle-name authenticated
!
!
!
!
!
!
!
!
!
redundancy
!
!
ip tcp synwait-time 5
!
!
!
!        
!
!
!
!
interface FastEthernet0/0
 ip address 192.168.12.1 255.255.255.0
 duplex auto
 speed auto
 !
!
interface FastEthernet0/1
 no ip address
 shutdown
 duplex auto
 speed auto
 !
!
interface FastEthernet1/0
 no ip address
 shutdown
 duplex auto
 speed auto
 !        
!
interface FastEthernet1/1
 no ip address
 shutdown
 duplex auto
 speed auto
 !
!
!
!
router eigrp 1
 network 192.168.12.0
!
ip forward-protocol nd
no ip http server
no ip http secure-server
!
!
!
no cdp log mismatch duplex
!
!
!        
!
!
!
control-plane
 !
!
!
mgcp fax t38 ecm
mgcp behavior g729-variants static-pt
!
!
!
gatekeeper
 shutdown
!
!
line con 0
 exec-timeout 0 0
 privilege level 15
 logging synchronous
 stopbits 1
line aux 0
 exec-timeout 0 0
 privilege level 15
 logging synchronous
 stopbits 1
line vty 0 4
 login
!
end

R1#


R2#sh run
Building configuration...

Current configuration : 1281 bytes
!
upgrade fpd auto
version 15.0
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R2
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
!
!
!
ip source-route
no ip icmp rate-limit unreachable
ip cef
!
!        
!
!
no ip domain lookup
no ipv6 cef
!
multilink bundle-name authenticated
!
!
!
!
!
!
!
!
!
redundancy
!
!
ip tcp synwait-time 5
!
!
!
!        
!
!
!
!
interface FastEthernet0/0
 ip address 192.168.23.2 255.255.255.0
 duplex auto
 speed auto
 !
!
interface FastEthernet0/1
 no ip address
 shutdown
 duplex auto
 speed auto
 !
!
interface FastEthernet1/0
 ip address 192.168.12.2 255.255.255.0
 duplex auto
 speed auto
 !
!        
interface FastEthernet1/1
 no ip address
 shutdown
 duplex auto
 speed auto
 !
!
!
!
router eigrp 1
 network 192.168.12.0
 network 192.168.23.0
!
ip forward-protocol nd
no ip http server
no ip http secure-server
!
!
ip default-network 192.168.23.0
!
no cdp log mismatch duplex
!
!        
!
!
!
!
control-plane
 !
!
!
mgcp fax t38 ecm
mgcp behavior g729-variants static-pt
!
!
!
gatekeeper
 shutdown
!
!
line con 0
 exec-timeout 0 0
 privilege level 15
 logging synchronous
 stopbits 1
line aux 0
 exec-timeout 0 0
 privilege level 15
 logging synchronous
 stopbits 1
line vty 0 4
 login
!
end

R2#
RoutersNetworking ProtocolsCisco
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Last Comment
jskfan
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Predrag Jovic
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When you are using command
ip default-network 192.168.23.0
It mark network as default network.
* - candidate default
C* - candidate for default network is directly connected interface
D* - candidate for default network learned from EIGRP protocol

Have in mind that default-network command is classfull!

You can find more details in Cisco article - Configuring a Gateway of Last Resort Using IP Commands
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jskfan
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ASKER

what does  * - candidate default,  mean in plain english ?

I also see : Gateway of last resort is not set

I thought the main purpose of ip default-network command, is to specify Gateway of Last Resort to other routers.

any clarifications ?

Thanks
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ASKER

Thank you
Routers
Routers

A router is a networking device that forwards data packets between computer networks. Routers perform the "traffic directing" functions on the Internet. The most familiar type of routers are home and small office cable or DSL routers that simply pass data, such as web pages, email, IM, and videos between computers and the Internet. More sophisticated routers, such as enterprise routers, connect large business or ISP networks up to the powerful core routers that forward data at high speed along the optical fiber lines of the Internet backbone. Though routers are typically dedicated hardware devices, use of software-based routers has grown increasingly common.

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