11-19-2013 02:01 AM - edited 03-07-2019 04:40 PM
hello l have a question about prefix list with 3 routers. l configure 3 router R-1 as the branch, R-2 as the WAN and R-3 the head office (with a lot of loopbacks).
l want to configure prefix list on the WAN(R-2) to block all address with /30 and some of the loopbacks from displaying on the branch office routing table.
it works fine but the problem is, l cannot ping from the branch to any of the loopback. the ICMP does't pass through WAN router.
it works fine with 2 routers as the configuration is done on the head office that will display and work fine.
---
Posted by WebUser Salis Mahama from Cisco Support Community App
Solved! Go to Solution.
11-19-2013 09:41 AM
It looks like its an expected behavior as per your configuration. R3 doesn't have information about any of the prefixes of R1 as per the routing table entry. For R3 to reach R1, atleast we need a default-route which is not available.
I EIGRP advertising the default route as "network 0.0.0.0" won't work until you have a static route like ip route 0.0.0.0 0.0.0.0
Thanks & Regards,
Karthick Murugan
CCIE#39285
11-19-2013 02:11 AM
Hi,
post topology diagram and the configs.
Regards
Alain
Don't forget to rate helpful posts.
11-19-2013 07:34 AM
R1 -
........-R-2----
R3
f0/0 10.1.1.0/30 f0/0 f0/1 10.9.1.0/30 f0/0
R1 config
............
interface FastEthernet0/0
ip address 10.1.1.2 255.255.255.252
speed 100
full-duplex
!
router eigrp 100
network 0.0.0.0
no auto-summary
!
R2 config
.........
interface FastEthernet0/0
ip address 10.1.1.1 255.255.255.252
speed 100
full-duplex
!
interface Serial0/0
ip address 10.9.1.5 255.255.255.252
clock rate 2000000
!
interface FastEthernet0/1
ip address 10.9.1.1 255.255.255.252
speed 100
full-duplex
!
router eigrp 100
network 0.0.0.0
distribute-list prefix BLK30 out
no auto-summary
!
!
ip prefix-list BLK30 seq 5 deny 0.0.0.0/0 ge 30 le 30
ip prefix-list BLK30 seq 10 permit 0.0.0.0/0 le 32
!
R3 config
...........
interface Loopback1
ip address 17.1.1.1 255.255.0.0
!
interface Loopback2
ip address 17.2.2.2 255.255.128.0
!
interface Loopback3
ip address 17.3.3.3 255.255.192.0
!
interface Loopback4
ip address 17.4.4.4 255.255.224.0
!
interface Loopback5
ip address 17.5.5.5 255.255.240.0
!
interface FastEthernet0/0
ip address 10.9.1.2 255.255.255.252
speed 100
full-duplex
!
interface FastEthernet0/1
ip address 10.9.1.9 255.255.255.252
speed 100
full-duplex
!
interface FastEthernet1/0
ip address 10.9.1.13 255.255.255.252
duplex auto
speed auto
!
router eigrp 100
network 0.0.0.0
no auto-summary
!
this is the show ip route on R1
Branch1#show ip route eigrp
17.0.0.0/8 is variably subnetted, 5 subnets, 5 masks
D 17.1.0.0/16 via 10.1.1.1, 00:13:03, FastEthernet0/0
D 17.3.0.0/18 via 10.1.1.1, 00:13:03, FastEthernet0/0
D 17.2.0.0/17 via 10.1.1.1, 00:13:03, FastEthernet0/0
D 17.5.0.0/20 via 10.1.1.1, 00:13:03, FastEthernet0/0
D 17.4.0.0/19 via 10.1.1.1, 00:13:03, FastEthernet0/0
10.0.0.0/8 is variably subnetted, 5 subnets, 3 masks
D 10.16.2.0/25 via 10.1.1.1, 00:12:58, FastEthernet0/0
D 10.16.3.0/25 via 10.1.1.1, 00:12:58, FastEthernet0/0
D 10.16.1.0/24 via 10.1.1.1, 00:12:58, FastEthernet0/0
D 10.16.4.0/25 via 10.1.1.1, 00:12:58, FastEthernet0/0
Branch1#
from the config it block all the ip address with /30 and allow everything else but the problem is, after this configuration l cannnot ping from R1 to the loopbacks on R3.
thanks for your help
---
Posted by WebUser Salis Mahama from Cisco Support Community App
11-19-2013 09:41 AM
It looks like its an expected behavior as per your configuration. R3 doesn't have information about any of the prefixes of R1 as per the routing table entry. For R3 to reach R1, atleast we need a default-route which is not available.
I EIGRP advertising the default route as "network 0.0.0.0" won't work until you have a static route like ip route 0.0.0.0 0.0.0.0
Thanks & Regards,
Karthick Murugan
CCIE#39285
11-19-2013 07:38 AM
it does't allow me to upload the design
---
Posted by WebUser Salis Mahama from Cisco Support Community App
11-20-2013 05:18 AM
thank you very much. the problem is, l did't configure the default route to get back from R3
---
Posted by WebUser Salis Mahama from Cisco Support Community App
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