™
1 position of confusion for some CCNA and CCNP candidates would be the distinction between configuring a static default route and using the Cisco routing command ip default-network.
In the beginning glance, they appear to perform precisely the same thing. Each configure a spot to which packets ought to be routed if there isn't a far more particular route from the routing desk.
The main distinction between both of these solutions is the fact configuring a static default route only defines a default route for the router you’re configuring it on, when ip default-network will propagate the route via its routing protocol.
Enable’s study the routing tables of a hub-and-spoke network utilizing the ip default-community command. R1 would be the hub and R2 and R3 are the spokes. They're specifically related through the community 172.12.123.0 /24, and every features a loopback using a 32-little bit mask which might be numbered according to the router quantity (one.one.one.1, etc.) RIP is managing on all three routers plus the loopbacks are advertised.
R1 has another serial interface With all the IP address 10.one.one.1 /24, which community has long been flagged for a default community With all the command ip default-community ten.0.0.0 . It's not becoming marketed by RIP.
The routing protocol will then publicize this route. With RIP, the default community is advertised as 0.0.0.0 . (With IGRP, it appears because the network selection, but is marked as an IGRP External route. ) This route is designated a applicant default route on R1, as we see with the asterisk close to the 10.0.0.0 /24 network (code desk taken out for brevity):
R1#present ip route
Gateway of past resort isn't established
one.0.0.0/32 is subnetted, 1 subnets
C one.one.one.1 is directly related, Loopback0
R two.0.0.0/eight [a hundred and twenty/1] via 172.twelve.123.2, 00:00:11, Serial0
R three.0.0.0/8 [one hundred twenty/1] by means of 172.twelve.123.3, 00:00:eleven, Serial0
172.12.0.0/16 is variably subnetted, 2 subnets, https://socialhattori.com/ two masks
C 172.twelve.21.0/thirty is immediately linked, BRI0
C 172.twelve.123.0/24 is specifically linked, Serial0
* ten.0.0.0/24 is subnetted, one subnets
C 10.1.1.0 is directly linked, Serial1
On R2 and R3, a default RIP route is currently viewed (code tables once more deleted):
R2#clearly show ip route
Gateway of final resort is 172.twelve.123.1 to network 0.0.0.0
R one.0.0.0/8 [a hundred and twenty/1] via 172.12.123.one, 00:00:00, Serial0.213
2.0.0.0/32 is subnetted, 1 subnets
C 2.2.2.two is immediately linked, Loopback0
R three.0.0.0/8 [120/2] through 172.12.123.1, 00:00:00, Serial0.213
172.12.0.0/16 is variably subnetted, 2 subnets, 2 masks
C 172.12.123.0/24 is right linked, Serial0.213
R* 0.0.0.0/0 [a hundred and twenty/one] by way of 172.12.123.1, 00:00:00, Serial0.213
R3#clearly show ip route
R 1.0.0.0/eight [one hundred twenty/one] through 172.twelve.123.1, 00:00:27, Serial0.31
R two.0.0.0/8 [a hundred and twenty/two] by means of 172.12.123.one, 00:00:28, Serial0.31
3.0.0.0/32 is subnetted, 1 subnets
C 3.3.three.three is right related, Loopback0
172.12.0.0/24 is subnetted, one subnets
C 172.twelve.123.0 is instantly connected, Serial0.31
R* 0.0.0.0/0 [a hundred and twenty/one] by way of 172.twelve.123.1, 00:00:28, Serial0.31
As well as the default route operates, because we can easily ping ten.one.one.one from each R2 and R3. Because they've no other match within their routing tables, they use the default route.
R2#ping 10.one.one.1
Form escape sequence to abort.
Sending five, a hundred-byte ICMP Echos to ten.1.1.1, timeout is two seconds:
!!!!!
Results amount is 100% (5/5), round-vacation min/avg/max = 68/sixty eight/68 ms
R3#ping ten.one.1.1
When determining no matter if to implement a default static route or maybe a default network, Take into account that If you prefer the routing protocol to propagate the default route, the ip default-community command will do this for you. But If you need just the area router to provide the default route, a static IP route is just how to go.