Propagating EIGRP Default Route
With the use of default routes a better network performance could be achieved. For example routers at the access layer don’t need to know all routes in whole network. By using a default route you can significantly reduce the size of router’s routing table thus improving performance. There are few ways to propagate a default route into EIGRP domain, read further to see them …
- Redistributed default route
- Default route by using ip default-network command
- Default route with network 0.0.0.0 command
- By using ip summary-address command
Here is the topology used in this lab

Before we begin configuration of default route injection, I will provide basic configuration for this lab
ISP
ISP(config)#interface fastEthernet 0/0 ISP(config-if)#ip address 10.0.0.1 255.255.255.0 ISP(config-if)#no shutdown ISP(config-if)#interface lo 0 ISP(config-if)#ip address 192.168.100.1 255.255.255.0 ISP(config)#ip route 192.168.0.0 255.255.255.0 fastEthernet 0/0
BORDER
BORDER(config)#interface fa0/0 BORDER(config-if)#ip address 192.168.0.3 255.255.255.0 BORDER(config-if)#no shutdown BORDER(config-if)#interface fa0/1 BORDER(config-if)#ip address 10.0.0.2 255.255.255.0 BORDER(config-if)#no shutdown BORDER(config)#router eigrp 1 BORDER(config-router)#network 192.168.0.0 255.255.255.0
R1
R1(config)#interface fa0/0 R1(config-if)#ip address 192.168.0.1 255.255.255.0 R1(config-if)#no shutdown R1(config)#router eigrp 1 R1(config-router)#network 192.168.0.0 255.255.255.0
R2
R1(config)#interface fa0/0 R1(config-if)#ip address 192.168.0.2 255.255.255.0 R1(config-if)#no shutdown R1(config)#router eigrp 1 R1(config-router)#network 192.168.0.0 255.255.255.0
From picture you can see that default route injection will be made by BORDER router and will send all unknown traffic to ISP router, that’s why I have put a static route on ISP toward BORDER for 192.168.0.0/24 network, just for test purposes. Now, let’s proceed to configuration !
Redistributed default route
To redistribute a default route into EIGRP, we need to have one. I used a static default route on BORDER which points to ISP.
BORDER(config)#ip route 0.0.0.0 0.0.0.0 10.0.0.1Now, redistribution command
BORDER(config-router)#redistribute static metric 10000 100 255 1 1500
Where metric values are:
- Bandwith – 10000 Kb/s (10 Mb/s);
- Delay – 100 (tens of microseconds, for 10Mb/s interface we have 1000 microseconds);
- Reliability – 255 (100% reliable);
- Loading – 1 (if 255 then 100% loaded);
- MTU – 1500.
R1#show ip route
... output omitted ...
Gateway of last resort is 192.168.0.3 to network 0.0.0.0
C 192.168.0.0/24 is directly connected, FastEthernet0/0
D*EX 0.0.0.0/0 [170/307200] via 192.168.0.3, 01:45:34, FastEthernet0/0
R1#
R1#ping 192.168.100.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.100.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 20/39/48 ms
R1#
From the output you see that we have a EIGRP route marked as default (D*EX) and a Gateway of last resort set, also ping to ISP’s loopback works fine.

Default route by using ip default-network command
Another method to generate a default route is by using ip default-network command. But first take into account few things:- Default network must be reachable by the router that advertise it;
- All routers that receive default network must know how to reach it through EIGRP.
BORDER(config)#ip route 192.168.100.0 255.255.255.0 fastEthernet 0/1 BORDER(config)#router eigrp 1 BORDER(config-router)#redistribute static metric 10000 100 255 1 1500
Now only remains to add ip default-network command on BORDER router and a default route will be generated
BORDER(config)#ip default-network 192.168.100.0
Let’s see the results on R1
R1#show ip route
... output omitted ...
Gateway of last resort is 192.168.0.3 to network 192.168.100.0
C 192.168.0.0/24 is directly connected, FastEthernet0/0
D*EX 192.168.100.0/24 [170/307200] via 192.168.0.3, 00:13:51, FastEthernet0/0
R1#
You have seen from output that a default route is injected into R1’s routing table

Default route with network 0.0.0.0 command
With this method you also need to have a default route on router that generates default route and then use network 0.0.0.0 command, check configurations on BORDER below
BORDER(config)#ip route 0.0.0.0 0.0.0.0 FastEthernet0/1 BORDER(config)#router eigrp 1 BORDER(config-router)#network 0.0.0.0
And now verification on R1
R1#show ip route
... output omitted ...
Gateway of last resort is 192.168.0.3 to network 0.0.0.0
D 10.0.0.0/8 [90/307200] via 192.168.0.3, 00:05:41, FastEthernet0/0
C 192.168.0.0/24 is directly connected, FastEthernet0/0
D* 0.0.0.0/0 [90/307200] via 192.168.0.3, 00:05:41, FastEthernet0/0
R1#
R1#ping 192.168.100.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.100.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 20/37/44 ms
R1#

By using ip summary-address command
An alternative method to those described above is to configure a manual summary route on a interface with summary address 0.0.0.0 and mask 0.0.0.0. Then, router will send a default route on that interface.
BORDER(config)#interface fastEthernet 0/0 BORDER(config-if)#ip summary-address eigrp 1 0.0.0.0 0.0.0.0 BORDER(config)#ip route 0.0.0.0 0.0.0.0 fastEthernet 0/1And now the results
R1#show ip route
... output omitted ...
Gateway of last resort is 192.168.0.3 to network 0.0.0.0
C 192.168.0.0/24 is directly connected, FastEthernet0/0
D* 0.0.0.0/0 [90/307200] via 192.168.0.3, 00:00:51, FastEthernet0/0
R1#
R1#ping 192.168.100.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.100.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 20/40/60 ms
R1#

Comments (11)
Kevrell
| #
THX that’s a great awnser!
Reply
bincy
| #
Excellent!
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arun
| #
Good stuff……….
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Apostolos_Greece
| #
Awesome tutorial !!!!! The best i have found on the internet!!!
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Dali
| #
Thanks, easy and clear.
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LEFTERIS
| #
very helpful….. thanks you
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nazari
| #
tnx for very nice and simple explanation
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AMIR NEZAM
| #
The best i have found on the internet!!!
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Rakesh Sharma
| #
Thanks ……Very clear explanation…
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Zubair Rehman
| #
I have spent the whole night searching for it and in the end you explained it so easy that it solved my problem.
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samir zouiki
| #
Thank’s it’s very helpful
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