08-27-2010 12:49 PM - edited 03-06-2019 12:41 PM
Hi Everyone,
I have router A->B->C running eigrp 1 on all of them. Router C is running Tunnel gre multipoint and all of its spokes connecting to C get summarization of certain subnets.
Router A is advertising 192.218.96.0/22 and 192.110.88.0/24
RouterC tunnel configuration
interface Tunnel0
bandwidth 1000
ip address 10.253.252.1 255.255.252.0
no ip redirects
ip mtu 1280
ip nhrp authentication Xxxxxx
ip nhrp map multicast dynamic
ip nhrp network-id 2
ip nhrp holdtime 300
ip nhrp server-only
ip nhrp max-send 500 every 10
ip nhrp shortcut
ip nhrp redirect
ip route-cache policy
ip route-cache flow
ip tcp adjust-mss 1240
no ip split-horizon eigrp 1
ip summary-address eigrp 1 192.218.96.0 255.255.252.0 5
ip summary-address eigrp 1 192.110.88.0 255.255.252.0 5
ip summary-address eigrp 1 0.0.0.0 0.0.0.0 5
ip policy route-map BB_Internet
delay 1001
tunnel source GigabitEthernet0/3
tunnel mode gre multipoint
tunnel key 2
tunnel protection ipsec profile PROFILE1
RouterC#sh ip route 192.218.96.0
Routing entry for 192.218.96.0/22
Known via "eigrp 1", distance 5, metric 2223872, type internal
Redistributing via eigrp 1
Routing Descriptor Blocks:
* directly connected, via Null0
Route metric is 2223872, traffic share count is 1
Total delay is 20210 microseconds, minimum bandwidth is 1500 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 2/255, Hops 3
RouterC#sh ip route 192.110.88.0
Routing entry for 192.110.88.0/24
Known via "eigrp 1", distance 90, metric 31488, type internal
Redistributing via eigrp 1
Last update from RouterB on GigabitEthernet0/1, 00:10:34 ago
Routing Descriptor Blocks:
* RouterB, from RouterB, 00:10:34 ago, via GigabitEthernet0/1
Route metric is 31488, traffic share count is 1
Total delay is 230 microseconds, minimum bandwidth is 100000 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 3/255, Hops 4
Question? Why 192.218.96.0/22 had a directly connected to Null0 and the other doesn't? Can someone help me understand the reason?
Thank you....
Cheers!!!
Solved! Go to Solution.
08-27-2010 02:38 PM
mguzman4158,
I just set this up on a few routers and the reason why you see the /24 is because IOS uses a longest-prefix match (/24 is longer than /22). If you type the following command, "show ip route eigrp" you can see all three routes as follows:
R1#show ip route eigrp
D 192.110.88.0/24 [90/409600] via 192.168.0.1, 00:05:04, FastEthernet0/0
D 192.110.88.0/22 is a summary, 00:00:44, Null0
D 192.218.96.0/22 [90/409600] via 192.168.0.1, 00:05:04, FastEthernet0/0
R1#show ip route 192.218.96.0
Routing entry for 192.218.96.0/22, supernet
Known via "eigrp 1", distance 90, metric 409600, type internal
Redistributing via eigrp 1
Last update from 192.168.0.1 on FastEthernet0/0, 00:05:37 ago
Routing Descriptor Blocks:
* 192.168.0.1, from 192.168.0.1, 00:05:37 ago, via FastEthernet0/0
Route metric is 409600, traffic share count is 1
Total delay is 6000 microseconds, minimum bandwidth is 10000 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 1
R1#show ip route 192.110.88.0
Routing entry for 192.110.88.0/24
Known via "eigrp 1", distance 90, metric 409600, type internal
Redistributing via eigrp 1
Last update from 192.168.0.1 on FastEthernet0/0, 00:05:51 ago
Routing Descriptor Blocks:
* 192.168.0.1, from 192.168.0.1, 00:05:51 ago, via FastEthernet0/0
Route metric is 409600, traffic share count is 1
Total delay is 6000 microseconds, minimum bandwidth is 10000 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 1
R1#
Also,
If you type the following command, "show ip eigrp topology" you can see both networks in the topology table.
R1#show ip eigrp topology
IP-EIGRP Topology Table for AS(1)/ID(192.168.0.2)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - reply Status, s - sia Status
P 192.168.0.0/30, 1 successors, FD is 281600
via Connected, FastEthernet0/0
P 192.168.1.0/30, 1 successors, FD is 281600
via Connected, FastEthernet0/1
P 192.218.96.0/22, 1 successors, FD is 409600
via 192.168.0.1 (409600/128256), FastEthernet0/0
P 192.110.88.0/22, 1 successors, FD is 409600
via Summary (409600/0), Null0
P 192.110.88.0/24, 1 successors, FD is 409600
via 192.168.0.1 (409600/128256), FastEthernet0/0
R1#
It's just the way IOS displays the routes for you... A longer prefix match is preferred over a lower administrative distance (/24 over /22 is preferred over AD 90 vs AD 5).
-Jeremy
08-27-2010 02:38 PM
mguzman4158,
I just set this up on a few routers and the reason why you see the /24 is because IOS uses a longest-prefix match (/24 is longer than /22). If you type the following command, "show ip route eigrp" you can see all three routes as follows:
R1#show ip route eigrp
D 192.110.88.0/24 [90/409600] via 192.168.0.1, 00:05:04, FastEthernet0/0
D 192.110.88.0/22 is a summary, 00:00:44, Null0
D 192.218.96.0/22 [90/409600] via 192.168.0.1, 00:05:04, FastEthernet0/0
R1#show ip route 192.218.96.0
Routing entry for 192.218.96.0/22, supernet
Known via "eigrp 1", distance 90, metric 409600, type internal
Redistributing via eigrp 1
Last update from 192.168.0.1 on FastEthernet0/0, 00:05:37 ago
Routing Descriptor Blocks:
* 192.168.0.1, from 192.168.0.1, 00:05:37 ago, via FastEthernet0/0
Route metric is 409600, traffic share count is 1
Total delay is 6000 microseconds, minimum bandwidth is 10000 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 1
R1#show ip route 192.110.88.0
Routing entry for 192.110.88.0/24
Known via "eigrp 1", distance 90, metric 409600, type internal
Redistributing via eigrp 1
Last update from 192.168.0.1 on FastEthernet0/0, 00:05:51 ago
Routing Descriptor Blocks:
* 192.168.0.1, from 192.168.0.1, 00:05:51 ago, via FastEthernet0/0
Route metric is 409600, traffic share count is 1
Total delay is 6000 microseconds, minimum bandwidth is 10000 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 1
R1#
Also,
If you type the following command, "show ip eigrp topology" you can see both networks in the topology table.
R1#show ip eigrp topology
IP-EIGRP Topology Table for AS(1)/ID(192.168.0.2)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - reply Status, s - sia Status
P 192.168.0.0/30, 1 successors, FD is 281600
via Connected, FastEthernet0/0
P 192.168.1.0/30, 1 successors, FD is 281600
via Connected, FastEthernet0/1
P 192.218.96.0/22, 1 successors, FD is 409600
via 192.168.0.1 (409600/128256), FastEthernet0/0
P 192.110.88.0/22, 1 successors, FD is 409600
via Summary (409600/0), Null0
P 192.110.88.0/24, 1 successors, FD is 409600
via 192.168.0.1 (409600/128256), FastEthernet0/0
R1#
It's just the way IOS displays the routes for you... A longer prefix match is preferred over a lower administrative distance (/24 over /22 is preferred over AD 90 vs AD 5).
-Jeremy
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