thanks Julio for your input. 

AD value is local signification on R1?  and what's the purpose of this Option that is following up with  the command " ip summary-address eigrp 1 10.0.0.0 255.0.0.0" without leak-map

do you have a example to show when we could use this AD option ? 

thanks, please let me know if possible.

Eric 

Hi

Yes the AD is locally significant, by default it creates a summary route with AD 5 and pointing to null, it is used to avoid loops. Now when the summary address is advertised it send the subnet with AD 90.

and what will be happened if we changed AD value to 100  ? ( > eigrp internal route AD=90)

could I possible know?

thanks, 

Eric 

If a summary subnet is advertised to a neighbor, it will create a default entry pointing to null0 with AD 5, it is used to prefer this entry and avoid layer 3 loops, now if you change the AD it could generate loops or black holes. 

For example is you change the AD to 255 it will not install a entry to null0 but it will be still advertising the summary address to the neighbor. 

Thanks very much Julio for your kindly explanation.

Based on my understanding for this summary route, regardless AD value is 5 or 250, it always be advertised out to neighbor.and on neighbor side, it will became normal eigrp route as AD 90.

so do you have a detail example about your comment below, that can help me better understand it ?

"If a summary subnet is advertised to a neighbor, it will create a default entry pointing to null0 with AD 5, it is used to prefer this entry and avoid layer 3 loops, now if you change the AD it could generate loops or black holes.  "

thanks in advance !

Eric 

Hi

https://www.safaribooksonline.com/library/view/cisco-ios-in/156592942X/re410.html

Imagine the attached topology. 

R1 Configuration (R2 & R3 have basic configuration, nothing special)

interface Loopback0
ip address 192.168.1.1 255.255.255.0 secondary
ip address 192.168.2.1 255.255.255.0 secondary
ip address 192.168.3.1 255.255.255.0 secondary
ip address 192.168.0.1 255.255.255.0
!
interface FastEthernet0/0
ip address 10.12.0.1 255.255.255.0
ip summary-address eigrp 100 192.168.0.0 255.255.252.0 100
duplex auto
speed auto
!
interface FastEthernet0/1
ip address 10.13.0.1 255.255.255.0
duplex auto
speed auto
!
router eigrp 100
network 0.0.0.0
no auto-summary

R1 is advertising a summary subnet to R2 only (not to R3) now you will see an unusual behavior on the routers, including R1, the summary entry to null0 will be flapping, now it is then not. The same for R2 and R3 the summary subnet will be flapping. 

R1#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

10.0.0.0/24 is subnetted, 3 subnets
C 10.12.0.0 is directly connected, FastEthernet0/0
C 10.13.0.0 is directly connected, FastEthernet0/1
D 10.23.0.0 [90/307200] via 10.13.0.3, 00:21:13, FastEthernet0/1
[90/307200] via 10.12.0.2, 00:21:13, FastEthernet0/0
C 192.168.0.0/24 is directly connected, Loopback0
C 192.168.1.0/24 is directly connected, Loopback0
C 192.168.2.0/24 is directly connected, Loopback0
C 192.168.3.0/24 is directly connected, Loopback0
D 192.168.0.0/22 [90/460800] via 10.13.0.3, 00:00:00, FastEthernet0/1
R1#
R1#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

10.0.0.0/24 is subnetted, 3 subnets
C 10.12.0.0 is directly connected, FastEthernet0/0
C 10.13.0.0 is directly connected, FastEthernet0/1
D 10.23.0.0 [90/307200] via 10.13.0.3, 00:21:16, FastEthernet0/1
[90/307200] via 10.12.0.2, 00:21:16, FastEthernet0/0
C 192.168.0.0/24 is directly connected, Loopback0
C 192.168.1.0/24 is directly connected, Loopback0
C 192.168.2.0/24 is directly connected, Loopback0
C 192.168.3.0/24 is directly connected, Loopback0
D 192.168.0.0/22 is a summary, 00:00:00, Null0
R1#

R1#sh ip eigrp eve
Event information for AS 100:
1 00:24:33.083 Change queue emptied, entries: 1
2 00:24:33.083 Route OBE net/refcount: 192.168.0.0/22 2
3 00:24:33.083 Metric set: 192.168.0.0/22 128256
4 00:24:33.083 Update reason, delay: new if 4294967295
5 00:24:33.083 Update sent, RD: 192.168.0.0/22 4294967295
6 00:24:33.083 Update reason, delay: metric chg 4294967295
7 00:24:33.083 Update sent, RD: 192.168.0.0/22 4294967295
8 00:24:33.083 Route install: 192.168.0.0/22 0.0.0.0
9 00:24:33.083 RDB delete: 192.168.0.0/22 10.12.0.2
10 00:24:33.083 RDB delete: 192.168.0.0/22 10.13.0.3
11 00:24:33.083 Find FS: 192.168.0.0/22 4294967295
12 00:24:33.083 Free reply status: 192.168.0.0/22
13 00:24:33.083 Clr handle num/bits: 0 0x0
14 00:24:33.083 Clr handle dest/cnt: 192.168.0.0/22 0
15 00:24:33.083 Rcv reply met/succ met: 4294967295 4294967295
16 00:24:33.079 Rcv reply dest/nh: 192.168.0.0/22 10.12.0.2
17 00:24:32.883 Send reply: 192.168.0.0/22 10.13.0.3
18 00:24:32.883 Rcv query met/succ met: 4294967295 4294967295
19 00:24:32.883 Rcv query dest/nh: 192.168.0.0/22 10.13.0.3
20 00:24:32.859 Clr handle num/bits: 1 0x1
21 00:24:32.859 Clr handle dest/cnt: 192.168.0.0/22 1
22 00:24:32.859 Rcv reply met/succ met: 460800 435200
23 00:24:32.859 Rcv reply dest/nh: 192.168.0.0/22 10.13.0.3
24 00:24:32.811 Poison squashed: 192.168.0.0/22 reverse
25 00:24:32.811 Metric set: 192.168.0.0/22 4294967295
26 00:24:32.811 Active net/peers: 192.168.0.0/22 2
27 00:24:32.811 FC not sat Dmin/met: 128256 128256
28 00:24:32.811 Find FS: 192.168.0.0/22 0
29 00:24:32.811 Route install: 192.168.0.0/22 10.13.0.3
30 00:24:32.811 Route install: 192.168.0.0/22 0.0.0.0
31 00:24:32.811 FC sat rdbmet/succmet: 128256 0
32 00:24:32.811 FC sat nh/ndbmet: 0.0.0.0 128256
33 00:24:32.811 Find FS: 192.168.0.0/22 128256
34 00:24:32.811 Rcv update met/succmet: 460800 435200
35 00:24:32.811 Rcv update dest/nh: 192.168.0.0/22 10.13.0.3
36 00:24:32.735 Change queue emptied, entries: 1
37 00:24:32.735 Route OBE net/refcount: 192.168.0.0/22 2
38 00:24:32.735 Metric set: 192.168.0.0/22 128256
39 00:24:32.735 Update reason, delay: new if 4294967295
40 00:24:32.735 Update sent, RD: 192.168.0.0/22 4294967295
41 00:24:32.735 Update reason, delay: metric chg 4294967295
42 00:24:32.735 Update sent, RD: 192.168.0.0/22 4294967295
43 00:24:32.735 Route install: 192.168.0.0/22 0.0.0.0
44 00:24:32.735 RDB delete: 192.168.0.0/22 10.12.0.2
45 00:24:32.735 RDB delete: 192.168.0.0/22 10.13.0.3
46 00:24:32.735 Find FS: 192.168.0.0/22 4294967295
47 00:24:32.735 Free reply status: 192.168.0.0/22
48 00:24:32.735 Clr handle num/bits: 0 0x0
49 00:24:32.735 Clr handle dest/cnt: 192.168.0.0/22 0
50 00:24:32.735 Rcv reply met/succ met: 4294967295 4294967295
51 00:24:32.735 Rcv reply dest/nh: 192.168.0.0/22 10.12.0.2
52 00:24:32.539 Clr handle num/bits: 1 0x1
53 00:24:32.539 Clr handle dest/cnt: 192.168.0.0/22 1
54 00:24:32.539 Rcv reply met/succ met: 4294967295 4294967295
55 00:24:32.539 Rcv reply dest/nh: 192.168.0.0/22 10.13.0.3
56 00:24:32.511 Send reply: 192.168.0.0/22 10.13.0.3
57 00:24:32.511 Rcv query met/succ met: 4294967295 4294967295
58 00:24:32.511 Rcv query dest/nh: 192.168.0.0/22 10.13.0.3
59 00:24:32.439 Metric set: 192.168.0.0/22 4294967295
60 00:24:32.439 Active net/peers: 192.168.0.0/22 2
61 00:24:32.439 FC not sat Dmin/met: 128256 128256
62 00:24:32.439 Find FS: 192.168.0.0/22 0
63 00:24:32.439 Route install: 192.168.0.0/22 10.13.0.3
64 00:24:32.439 Route install: 192.168.0.0/22 0.0.0.0

R2 routing table. 

R2>ENA
R2#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

10.0.0.0/24 is subnetted, 3 subnets
C 10.12.0.0 is directly connected, FastEthernet0/0
D 10.13.0.0 [90/307200] via 10.23.0.3, 00:10:34, FastEthernet0/1
[90/307200] via 10.12.0.1, 00:10:34, FastEthernet0/0
C 10.23.0.0 is directly connected, FastEthernet0/1
D 192.168.0.0/24 [90/435200] via 10.23.0.3, 00:09:14, FastEthernet0/1
D 192.168.1.0/24 [90/435200] via 10.23.0.3, 00:09:14, FastEthernet0/1
D 192.168.2.0/24 [90/435200] via 10.23.0.3, 00:09:14, FastEthernet0/1
D 192.168.3.0/24 [90/435200] via 10.23.0.3, 00:09:16, FastEthernet0/1
R2#

R2#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

10.0.0.0/24 is subnetted, 3 subnets
C 10.12.0.0 is directly connected, FastEthernet0/0
D 10.13.0.0 [90/307200] via 10.23.0.3, 00:10:37, FastEthernet0/1
[90/307200] via 10.12.0.1, 00:10:37, FastEthernet0/0
C 10.23.0.0 is directly connected, FastEthernet0/1
D 192.168.0.0/24 [90/435200] via 10.23.0.3, 00:09:17, FastEthernet0/1
D 192.168.1.0/24 [90/435200] via 10.23.0.3, 00:09:17, FastEthernet0/1
D 192.168.2.0/24 [90/435200] via 10.23.0.3, 00:09:17, FastEthernet0/1
D 192.168.3.0/24 [90/435200] via 10.23.0.3, 00:09:19, FastEthernet0/1
D 192.168.0.0/22 [90/409600] via 10.12.0.1, 00:00:00, FastEthernet0/0
R2#
R2#
R2#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

10.0.0.0/24 is subnetted, 3 subnets
C 10.12.0.0 is directly connected, FastEthernet0/0
D 10.13.0.0 [90/307200] via 10.23.0.3, 00:10:40, FastEthernet0/1
[90/307200] via 10.12.0.1, 00:10:40, FastEthernet0/0
C 10.23.0.0 is directly connected, FastEthernet0/1
D 192.168.0.0/24 [90/435200] via 10.23.0.3, 00:09:20, FastEthernet0/1
D 192.168.1.0/24 [90/435200] via 10.23.0.3, 00:09:20, FastEthernet0/1
D 192.168.2.0/24 [90/435200] via 10.23.0.3, 00:09:20, FastEthernet0/1
D 192.168.3.0/24 [90/435200] via 10.23.0.3, 00:09:21, FastEthernet0/1
D 192.168.0.0/22 [90/409600] via 10.12.0.1, 00:00:00, FastEthernet0/0
R2#

R3 Routing table

R3#
R3#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

10.0.0.0/24 is subnetted, 3 subnets
D 10.12.0.0 [90/307200] via 10.23.0.2, 00:01:51, FastEthernet0/0
[90/307200] via 10.13.0.1, 00:01:51, FastEthernet0/1
C 10.13.0.0 is directly connected, FastEthernet0/1
C 10.23.0.0 is directly connected, FastEthernet0/0
D 192.168.0.0/24 [90/409600] via 10.13.0.1, 00:01:51, FastEthernet0/1
D 192.168.1.0/24 [90/409600] via 10.13.0.1, 00:01:51, FastEthernet0/1
D 192.168.2.0/24 [90/409600] via 10.13.0.1, 00:01:51, FastEthernet0/1
D 192.168.3.0/24 [90/409600] via 10.13.0.1, 00:01:53, FastEthernet0/1
R3#
R3#
R3#
R3#
R3#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

10.0.0.0/24 is subnetted, 3 subnets
D 10.12.0.0 [90/307200] via 10.23.0.2, 00:08:08, FastEthernet0/0
[90/307200] via 10.13.0.1, 00:08:08, FastEthernet0/1
C 10.13.0.0 is directly connected, FastEthernet0/1
C 10.23.0.0 is directly connected, FastEthernet0/0
D 192.168.0.0/24 [90/409600] via 10.13.0.1, 00:08:08, FastEthernet0/1
D 192.168.1.0/24 [90/409600] via 10.13.0.1, 00:08:08, FastEthernet0/1
D 192.168.2.0/24 [90/409600] via 10.13.0.1, 00:08:08, FastEthernet0/1
D 192.168.3.0/24 [90/409600] via 10.13.0.1, 00:08:10, FastEthernet0/1
R3#
R3#
R3#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

10.0.0.0/24 is subnetted, 3 subnets
D 10.12.0.0 [90/307200] via 10.23.0.2, 00:08:12, FastEthernet0/0
[90/307200] via 10.13.0.1, 00:08:12, FastEthernet0/1
C 10.13.0.0 is directly connected, FastEthernet0/1
C 10.23.0.0 is directly connected, FastEthernet0/0
D 192.168.0.0/24 [90/409600] via 10.13.0.1, 00:08:12, FastEthernet0/1
D 192.168.1.0/24 [90/409600] via 10.13.0.1, 00:08:12, FastEthernet0/1
D 192.168.2.0/24 [90/409600] via 10.13.0.1, 00:08:12, FastEthernet0/1
D 192.168.3.0/24 [90/409600] via 10.13.0.1, 00:08:13, FastEthernet0/1
D 192.168.0.0/22 [90/435200] via 10.23.0.2, 00:00:00, FastEthernet0/0
R3#
R3#
R3#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

10.0.0.0/24 is subnetted, 3 subnets
D 10.12.0.0 [90/307200] via 10.23.0.2, 00:08:14, FastEthernet0/0
[90/307200] via 10.13.0.1, 00:08:14, FastEthernet0/1
C 10.13.0.0 is directly connected, FastEthernet0/1
C 10.23.0.0 is directly connected, FastEthernet0/0
D 192.168.0.0/24 [90/409600] via 10.13.0.1, 00:08:14, FastEthernet0/1
D 192.168.1.0/24 [90/409600] via 10.13.0.1, 00:08:14, FastEthernet0/1
D 192.168.2.0/24 [90/409600] via 10.13.0.1, 00:08:14, FastEthernet0/1
D 192.168.3.0/24 [90/409600] via 10.13.0.1, 00:08:16, FastEthernet0/1
R3#

Hope it is useful

:-)

yes, this test made more sense to me. thanks very much for your help on this case and really appreciated !

one more thing, could you please help me verify that, when you changed summary address AD  from 5 to 100, for these more specific routes such as : 192.168.0.0/24, still couldn't be advertised out to R2 through interface  FastEthernet0/0 ? 

thanks Again!

Eric 

Eric

The AD assigned to the generated summary route (whether it is 5 or 100 or something else) does not have any impact on what is advertised to the neighbor on the interface with summary address configured. If you configure  summary address 10.0.0.0 255.0.0.0 on an interface then that summary is advertised to the neighbor and no more specific route such as 10.8.1.0 will be advertised to that neighbor.

I believe that Julio is correct that the only way to advertise the more specific route would be to use the leak map.

HTH

Rick

thanks Richard for helping clarify this concept !.

Right now, only confusing for me: if without using leak-map, when we could use AD option ?

thanks!

Eric 

hi Richard, 

My original question:

1, if we changed AD from default value 5 to 100, if more specific routes could be advertised out   along with summary route together to neighbor? 

I already got your answer, it is NO.

2, what's better scenario, we could use AD option ?

PS: I used 10.0.0.0 subnet  as example, and Julio is using 192.168.0.0 subnet for testing. sorry for this confusion.

thanks, 

Eric 

Hi Eric

Happy to know our information is being useful. I think there are no too much situations in the real world where the AD should be modified, but if you want to use change the AD in order to fix any inconveniences should be:

Imagine 3 routers:

R1 ---- R2  ----- R3

Now R1 is sending a summary default route to R2 and R2 is sending a summary default route to R3, what will happen?

R2 will install a entry to null0 and will prefer this entry instead the default route provided by R1, so it is an issue, it could be fixed if you change the AD on R2 to be greater than 90

R2 with AD 5  (no modification) sending to R3

R2#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 0.0.0.0 to network 0.0.0.0

1.0.0.0/32 is subnetted, 1 subnets
D 1.1.1.1 [90/409600] via 10.12.0.1, 00:06:39, FastEthernet0/0
3.0.0.0/32 is subnetted, 1 subnets
D 3.3.3.3 [90/409600] via 10.23.0.3, 00:06:25, FastEthernet0/1
10.0.0.0/24 is subnetted, 3 subnets
C 10.12.0.0 is directly connected, FastEthernet0/0
D 10.13.0.0 [90/307200] via 10.23.0.3, 00:09:58, FastEthernet0/1
[90/307200] via 10.12.0.1, 00:09:58, FastEthernet0/0
C 10.23.0.0 is directly connected, FastEthernet0/1
D* 0.0.0.0/0 is a summary, 00:09:11, Null0

Now R2 with AD greater than 90

interface FastEthernet0/1
ip address 10.23.0.2 255.255.255.0
ip summary-address eigrp 100 0.0.0.0 0.0.0.0 100
duplex auto
speed auto
end

R2#sh ip
*Mar 1 00:11:45.791: %SYS-5-CONFIG_I: Configured from console by consoleroute
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 10.12.0.1 to network 0.0.0.0

1.0.0.0/32 is subnetted, 1 subnets
D 1.1.1.1 [90/409600] via 10.12.0.1, 00:07:37, FastEthernet0/0
3.0.0.0/32 is subnetted, 1 subnets
D 3.3.3.3 [90/409600] via 10.23.0.3, 00:07:23, FastEthernet0/1
10.0.0.0/24 is subnetted, 3 subnets
C 10.12.0.0 is directly connected, FastEthernet0/0
D 10.13.0.0 [90/307200] via 10.23.0.3, 00:10:56, FastEthernet0/1
[90/307200] via 10.12.0.1, 00:10:56, FastEthernet0/0
C 10.23.0.0 is directly connected, FastEthernet0/1
D* 0.0.0.0/0 [90/281600] via 10.12.0.1, 00:00:05, FastEthernet0/0

Now R2 has a valid default route entry on its routing table.

Hope it is useful

:-)

yes, this is other case for sure.

thanks for sharing it,Julio.

Eric