ip default-network, i hate this command

[norteldude78]

ok 3 routers:
corinth ---> sparta ---> athens ---> f0/0

all running eigrp
on the right side of athens is a network 10.1.1.0/24
this network shows up in corinth's routing table.
I use the following command on athens to mark the network as default:

ip default-network 10.0.0.0
I also advertise the network via eigrp.
yet corinth is not seeing it as the default route.
can you see why?

Here are my configs, I put descriptions on the interfaces.

corinth:

interface FastEthernet0/0
 description LAN interface
 ip address 172.16.4.1 255.255.255.0
 duplex auto
 speed auto
 ipv6 address 2001:DB8:0:4::1/64
!
interface Serial1/0
 description connectiopn to Sparta
 ip address 172.16.3.1 255.255.255.0
 ipv6 address 2001:DB8:0:3::1/64
 serial restart-delay 0
!
interface Serial1/3
 description connection to Athens
 ip address 172.16.5.1 255.255.255.0
 serial restart-delay 0
!
router eigrp 1
 network 172.16.0.0
 no auto-summary

sparta:

interface Serial1/0
 description connection to corinth
 ip address 172.16.3.2 255.255.255.0
 ipv6 address 2001:DB8:0:3::2/64
 serial restart-delay 0
!
interface Serial1/1
 description another router not in picture
 ip address 172.16.2.2 255.255.255.0
 ipv6 address 2001:DB8:0:2::2/64
 serial restart-delay 0
!
interface Serial1/2
 description connection to athens
 ip address 172.16.1.2 255.255.255.0
 ipv6 address 2001:DB8:0:1::2/64
 serial restart-delay 0
!
router eigrp 1
 network 172.16.0.0
 no auto-summary

athens:

interface FastEthernet0/0
 ip address 10.1.1.4 255.255.255.0
 duplex auto
 speed auto
 ipv6 address 2001:DB8:0:A1::4/64
!
interface Serial1/2
 description connection to sparta
 ip address 172.16.1.4 255.255.255.0
 ipv6 address 2001:DB8:0:1::4/64
 serial restart-delay 0
!
router eigrp 1
 network 10.0.0.0
 network 172.16.0.0
 no auto-summary
!
ip default-network 10.0.0.0
!

Route tables:

corinth:

Gateway of last resort is not set

     172.16.0.0/24 is subnetted, 6 subnets
C       172.16.4.0 is directly connected, FastEthernet0/0
C       172.16.5.0 is directly connected, Serial1/3
D       172.16.6.0 [90/2195456] via 172.16.5.3, 00:11:42, Serial1/3
D       172.16.1.0 [90/2681856] via 172.16.3.2, 00:11:42, Serial1/0
D       172.16.2.0 [90/2681856] via 172.16.5.3, 00:11:45, Serial1/3
                   [90/2681856] via 172.16.3.2, 00:11:45, Serial1/0
C       172.16.3.0 is directly connected, Serial1/0
     10.0.0.0/24 is subnetted, 1 subnets
D       10.1.1.0 [90/2707456] via 172.16.3.2, 00:11:41, Serial1/0

sparta:

Gateway of last resort is not set

     172.16.0.0/24 is subnetted, 6 subnets
D       172.16.4.0 [90/2195456] via 172.16.3.1, 00:11:58, Serial1/0
D       172.16.5.0 [90/2681856] via 172.16.3.1, 00:11:58, Serial1/0
                   [90/2681856] via 172.16.2.3, 00:11:58, Serial1/1
D       172.16.6.0 [90/2195456] via 172.16.2.3, 00:11:58, Serial1/1
C       172.16.1.0 is directly connected, Serial1/2
C       172.16.2.0 is directly connected, Serial1/1
C       172.16.3.0 is directly connected, Serial1/0
     10.0.0.0/24 is subnetted, 1 subnets
D       10.1.1.0 [90/2195456] via 172.16.1.4, 00:11:58, Serial1/2

athens:

Gateway of last resort is not set

     172.16.0.0/24 is subnetted, 6 subnets
D       172.16.4.0 [90/2707456] via 172.16.1.2, 00:12:14, Serial1/2
D       172.16.5.0 [90/3193856] via 172.16.1.2, 00:12:14, Serial1/2
D       172.16.6.0 [90/2707456] via 172.16.1.2, 00:12:12, Serial1/2
C       172.16.1.0 is directly connected, Serial1/2
D       172.16.2.0 [90/2681856] via 172.16.1.2, 00:12:14, Serial1/2
D       172.16.3.0 [90/2681856] via 172.16.1.2, 00:12:14, Serial1/2
 *   10.0.0.0/24 is subnetted, 1 subnets
C       10.1.1.0 is directly connected, FastEthernet0/0

any ideas?
i tried changing the default-network command to 10.1.1.0 but this didn't work either.

thanks

 

[burtsbees]

Not sure this works for EIGRP...I have used this with static routing, but not a routing protocol. You may have to try redistribute commands (static/connected) for this to work like the ip default-network command. I imagine this is a lab? This may work with RIP, though...

Burt

 

[norteldude78]

Thanks Burt...yep, this is a lab. It's actually chapter 12, page 687 of Doyle's Routing tcp/ip volume 1. The first step is to do it with RIP and that worked. Then they do it with EIGRP...but mine isn't working...

 

[burtsbees]

I'll have to look that one up...I think I have both volumes...

Burt

 

[burtsbees]

I have both the hard copies and pdf versions of vol 1 and 2, but I can't find the hard copies at the moment (must be at work)...what is the name of the chapter?

Burt

 

[norteldude78]

chapter is called "default routes and on-demand routing" its volume 1 second edition. the example is in the 1st edition as well. the heading is "case study: The default-network command"

thanks

 

[burtsbees]

Do you have a fourth router at 172.16.2.x? If so, have you tried to plug the default-network in this router? It looks to me that with a topology of only 3 routers, that network might have to be one more hop away.

Burt

 

[norteldude78]

i have a fourth router plugged into sparta, this is kind of parallel to corinth. according to the book, which has example outputs this should work...im curious to know how eigrp marks a route as default in it's advertisements, it must use a flag of some sort...sparta would get this and most certainly pass it to the others, i mean the 10.1.1.0 route is in the tables...just not marking it as default

i could add another router off of corinth...

 

[brianinms]

I am not at home so I don't have access to the above mentioned book. However here is some information on the ip default-network command. Look closely at the examples.

http://www.cisco.com/warp/public/105/default.html

 

[burtsbees]

EIGRP marks the default route as a route, rather than 0.0.0.0

I labbed this up, and here are the routes before the command...

Argos#sh 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 not set

172.16.0.0/24 is subnetted, 4 subnets
C 172.16.5.0 is directly connected, Serial0/1
D 172.16.1.0 [90/2172416] via 172.16.2.2, 00:00:08, Serial0/0
C 172.16.2.0 is directly connected, Serial0/0
D 172.16.3.0 [90/2681856] via 172.16.5.2, 00:00:08, Serial0/1
[90/2681856] via 172.16.2.2, 00:00:08, Serial0/0
D 10.0.0.0/8 [90/2684416] via 172.16.2.2, 00:00:08, Serial0/0
Argos#
Corinth#sh ip rou
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default
U - per-user static route, o - ODR

Gateway of last resort is not set

172.16.0.0/24 is subnetted, 4 subnets
C 172.16.5.0 is directly connected, Serial0
D 172.16.1.0 [90/2684416] via 172.16.5.1, 00:00:52, Serial0
D 172.16.2.0 [90/2681856] via 172.16.5.1, 00:00:53, Serial0
C 172.16.3.0 is directly connected, Serial1
D 10.0.0.0/8 [90/3196416] via 172.16.5.1, 00:00:52, Serial0
Corinth#
Sparta>en
Sparta#sh 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 not set

172.16.0.0/24 is subnetted, 4 subnets
D 172.16.5.0 [90/2681856] via 172.16.2.1, 00:01:12, Serial0/0
C 172.16.1.0 is directly connected, FastEthernet0/0
C 172.16.2.0 is directly connected, Serial0/0
C 172.16.3.0 is directly connected, Serial0/1
D 10.0.0.0/8 [90/2172416] via 172.16.1.2, 04:43:01, FastEthernet0/0
Sparta#
Athens>en
Athens#sh ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
i - IS-IS, 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 not set

172.16.0.0/16 is variably subnetted, 5 subnets, 2 masks
D 172.16.5.0/24 [90/2684416] via 172.16.1.1, 00:01:30, FastEthernet0/0
D 172.16.0.0/16 is a summary, 04:43:19, Null0
C 172.16.1.0/24 is directly connected, FastEthernet0/0
D 172.16.2.0/24 [90/2172416] via 172.16.1.1, 00:01:32, FastEthernet0/0
D 172.16.3.0/24 [90/2172416] via 172.16.1.1, 04:50:17, FastEthernet0/0
10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
D 10.0.0.0/8 is a summary, 04:43:19, Null0
C 10.1.1.0/24 is directly connected, Serial0/0

and then...

Athens(config)#ip default-network 10.0.0.0
Athens(config)#exi
Athens#
05:07:52: %SYS-5-CONFIG_I: Configured from console by consolewr
Building configuration...
[OK]

and the routing tables now...

Athens#sh ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
i - IS-IS, 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 0.0.0.0 to network 10.0.0.0

172.16.0.0/16 is variably subnetted, 5 subnets, 2 masks
D 172.16.5.0/24 [90/2684416] via 172.16.1.1, 00:02:44, FastEthernet0/0
D 172.16.0.0/16 is a summary, 04:44:32, Null0
C 172.16.1.0/24 is directly connected, FastEthernet0/0
D 172.16.2.0/24 [90/2172416] via 172.16.1.1, 00:02:46, FastEthernet0/0
D 172.16.3.0/24 [90/2172416] via 172.16.1.1, 04:51:31, FastEthernet0/0
* 10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
D* 10.0.0.0/8 is a summary, 04:44:33, Null0
C 10.1.1.0/24 is directly connected, Serial0/0
Athens#
Corinth#sh ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default
U - per-user static route, o - ODR

Gateway of last resort is 172.16.5.1 to network 10.0.0.0

172.16.0.0/24 is subnetted, 4 subnets
C 172.16.5.0 is directly connected, Serial0
D 172.16.1.0 [90/2684416] via 172.16.5.1, 00:03:07, Serial0
D 172.16.2.0 [90/2681856] via 172.16.5.1, 00:03:09, Serial0
C 172.16.3.0 is directly connected, Serial1
D* 10.0.0.0/8 [90/3196416] via 172.16.5.1, 00:00:42, Serial0
Corinth#
Argos#sh 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 172.16.2.2 to network 10.0.0.0

172.16.0.0/24 is subnetted, 4 subnets
C 172.16.5.0 is directly connected, Serial0/1
D 172.16.1.0 [90/2172416] via 172.16.2.2, 00:03:24, Serial0/0
C 172.16.2.0 is directly connected, Serial0/0
D 172.16.3.0 [90/2681856] via 172.16.5.2, 00:03:24, Serial0/1
[90/2681856] via 172.16.2.2, 00:03:24, Serial0/0
D* 10.0.0.0/8 [90/2684416] via 172.16.2.2, 00:00:59, Serial0/0
Argos#
Sparta#sh 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 172.16.1.2 to network 10.0.0.0

172.16.0.0/24 is subnetted, 4 subnets
D 172.16.5.0 [90/2681856] via 172.16.2.1, 00:03:41, Serial0/0
C 172.16.1.0 is directly connected, FastEthernet0/0
C 172.16.2.0 is directly connected, Serial0/0
C 172.16.3.0 is directly connected, Serial0/1
D* 10.0.0.0/8 [90/2172416] via 172.16.1.2, 00:01:15, FastEthernet0/0

It works for me, labbed up exactly as the book. Note I consoled from one router to the next, and the next, and so on---too lazy for vty passwords...lol

Corinth=2503, Argos, Sparta and Athens=2620's. What router do you have connected to Sparta? Is this where you are putting the command "ip default-network 10.0.0.0"? Is your topology like Corinth, Argos and Sparta all in a triangle, and off of Sparta is Athens?

Also, remember that for networks to be advertised, the links have to be up, so you must have something connected to 10.0.0.0

Burt

 

[burtsbees]

For those without access to the book, the topology is...

Corinth
| \
| \
| \
| Sparta---------Athens--------another router
| /
| /
| /
Argos

Burt

 

[brianinms]

According to the link I posted, if you use the ip default-network command you have to have a static route pointing that network to the proper next hop.

 

[burtsbees]

I don't...

Athens>en
Athens#sh run
Building configuration...

Current configuration:
!
version 12.0
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname Athens
!
!
!
!
!
!
ip subnet-zero
!
!
!
!
!
!
interface FastEthernet0/0
ip address 172.16.1.2 255.255.255.0
no ip directed-broadcast
duplex auto
speed auto
!
interface Serial0/0
ip address 10.1.1.1 255.255.255.0
no ip directed-broadcast
no ip mroute-cache
no fair-queue
clockrate 4000000
!
router eigrp 69
network 10.0.0.0
network 172.16.0.0
!
ip classless
ip default-network 10.0.0.0
no ip http server
!
!
line con 0
transport input none
line aux 0
line vty 0 4
!
no scheduler allocate
end

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

Sparta#sh run
Building configuration...

Current configuration : 843 bytes
!
version 12.3
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Sparta
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
!
resource policy
!
ip subnet-zero
ip cef
!
!
no ip dhcp use vrf connected
!
!
no ip ips deny-action ips-interface
!
no ftp-server write-enable
!
!
!
!
!
no crypto isakmp ccm
!
!
!
interface FastEthernet0/0
ip address 172.16.1.1 255.255.255.0
duplex auto
speed auto
!
interface Serial0/0
ip address 172.16.2.2 255.255.255.0
no fair-queue
no dce-terminal-timing-enable
!
interface Serial0/1
ip address 172.16.3.1 255.255.255.0
no dce-terminal-timing-enable
!
router eigrp 69
network 172.16.0.0
auto-summary
!
ip classless
!
ip http server
no ip http secure-server
!
!
!
control-plane
!
!
!
!
line con 0
line aux 0
line vty 0 4
!
!
end

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

Argos>en
Argos#sh run
Building configuration...

Current configuration : 862 bytes
!
version 12.3
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Argos
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
!
resource policy
!
ip subnet-zero
ip cef
!
!
no ip dhcp use vrf connected
!
!
no ip ips deny-action ips-interface
no ip domain lookup
!
no ftp-server write-enable
!
!
!
!
!
no crypto isakmp ccm
!
!
!
interface FastEthernet0/0
ip address 172.16.6.1 255.255.255.0
duplex auto
speed auto
!
interface Serial0/0
ip address 172.16.2.1 255.255.255.0
no fair-queue
no dce-terminal-timing-enable
!
interface Serial0/1
ip address 172.16.5.1 255.255.255.0
no dce-terminal-timing-enable
!
router eigrp 69
network 172.16.0.0
auto-summary
!
ip classless
!
ip http server
no ip http secure-server
!
!
!
control-plane
!
!
!
!
line con 0
line aux 0
line vty 0 4
!
!
end

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

Corinth>en
Corinth#sh run
Building configuration...

Current configuration:
!
version 11.3
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname Corinth
!
!
!
!
interface Ethernet0
ip address 172.16.4.1 255.255.255.0
!
interface Serial0
ip address 172.16.5.2 255.255.255.0
no ip mroute-cache
no fair-queue
clockrate 4000000
!
interface Serial1
ip address 172.16.3.1 255.255.255.0
clockrate 4000000
!
interface BRI0
no ip address
shutdown
!
router eigrp 69
network 172.16.0.0
!
ip classless
!
!
line con 0
line aux 0
line vty 0 4
login
!
end

Athens is connected to a 2620XM, int s0/1, ip add 10.1.1.2/24...

Burt

 

[jneiberger]

I would just like to throw in the perfectly useless comment that the ip default-network command is one of the reasons I hate EIGRP. If I need to propagate a default route through a network, I use OSPF. EIGRP is just so weird about it.

 

[norteldude78]

oh my goodness, you will never guess what the problem was...i'm sitting here just completely stumped looking at me config on athens and I notice "no auto-summary"...something I do every time i configure eigrp...

i remember reading about ip-default network needing a classful network. I just had to find the link so here it is:

http://blog.internetworkexpert.com/2008/01/15/issues-with-the-ip-default-network-command/

....so I went back to auto-summary and immediately the route had * next to it, now it's working...

man, I almost gave up...i kind of feel like the giants against patriots...never give up and you will conquer!

thanks everyone, im studying for ccie lab so i am sure you will see many more posts from me

 

[namesrhard2pick]

I was just about to recommend you change the "no auto-summary" to "auto summary".....just joking....

Good catch...my head is still spinning from looking at your and burts configs. Good stuff.