From: Shibu Nair (shinair@cisco.com)
Date: Wed Feb 04 2004 - 04:32:43 GMT-3
Hi
http://www.cisco.com/en/US/products/sw/iosswrel/ps1831/products_configuration_guide_chapter09186a00800d97f7.html#1001151
According to CCO documentation,
*****************************************************************************************************************
The following example shows how the ip summary-address rip command works
with autosummary addressing in RIP, starting in global configuration mode.
In the example, the major network is 10.0.0.0. The summary address 10.2.0.0
overrides the autosummary address of 10.0.0.0, so that 10.2.0.0 is
advertised out interface e1 and 10.0.0.0 is not advertised.
Note If split horizon is enabled, neither autosummary nor interface summary
addresses (those configured with the ip summary-address rip command) are
advertised.
******************************************************************************************************************
1)
If split horizon is enabled, auto-sumamry or manual interface summary
should not work.
I have the following setup
R4 -----Ethernet----- R3 ------- Serial--------R7
All routers are running RIP v2
I have created a loopback interface on R4 with 12.12.12.12 255.252.0.0
Enabled split horizon on all interfaces (default). RIP Auto-summary is "on"
(default).
Q1) Since split horizon is turned "on" on R4 and R1, i should not see the
auto summary 12.0.0.0 /8 according
to the theory mentioned above. But I am always seeing 12.0.0.0 /8 on R3
irrespective of whether split-horizon is
enabled or disabled R3 and R4.
R#:
R 12.0.0.0/8 [120/1] via 192.168.12.196, 00:00:01, Ethernet2/0
I have tried with and without split horizon but the result is same.
Am i missing anything here... ?
2) Manual summary
I have enabled manual summary on R3 towards R7 for the following,
interface Serial5/0
ip address 172.17.2.3 255.255.255.0
ip summary-address rip 12.12.0.0 255.255.0.0
But on R7 I still see,
R 12.0.0.0/8 [120/2] via 172.17.2.3, 00:00:18, Serial4/0
I thought i should see /16 since manual summary is enabled on R3 towards R7.
I have tried enabling/disabling split horizon. My understanding is that, if
auto-summary and manual summary enabled,
always manual summary (interface summary) dominate.
Please advice me on these.
Regards
Shibu
R3:
R3#sh runn
Building configuration...
Current configuration : 858 bytes
!
version 12.2
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname R3
!
!
clock timezone EST -5
ip subnet-zero
!
!
!
!
interface Ethernet0/0
ip address 192.168.83.3 255.255.255.0
!
interface Ethernet1/0
ip address 192.168.12.65 255.255.255.224
!
interface Ethernet2/0
ip address 192.168.12.195 255.255.255.224
!
interface Serial3/0
ip address 172.17.1.3 255.255.255.0
no fair-queue
!
interface Serial4/0
no ip address
shutdown
!
interface Serial5/0
ip address 172.17.2.3 255.255.255.0
ip summary-address rip 12.12.0.0 255.255.0.0
!
interface Serial6/0
no ip address
shutdown
!
router rip
version 2
passive-interface Serial3/0
network 172.17.0.0
network 192.168.12.0
no auto-summary
!
ip classless
no ip http server
ip pim bidir-enable
!
!
!
line con 0
line aux 0
line vty 0 4
login
!
end
R3#
R4>en
R4#sh runn
Building configuration...
Current configuration : 763 bytes
!
version 12.2
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname R4
!
!
clock timezone EST -5
ip subnet-zero
no ip domain lookup
!
!
!
!
interface Loopback0
ip address 12.12.12.12 255.252.0.0
!
interface Ethernet0/0
ip address 10.33.35.4 255.255.240.0
no keepalive
!
interface Ethernet1/0
no ip address
shutdown
!
interface Ethernet2/0
ip address 192.168.12.196 255.255.255.224
!
interface Serial3/0
no ip address
shutdown
!
interface Serial4/0
no ip address
shutdown
!
interface Serial5/0
ip address 10.33.90.4 255.255.240.0
!
router rip
version 2
network 12.0.0.0
network 192.168.12.0
!
ip classless
no ip http server
ip pim bidir-enable
!
!
!
line con 0
line aux 0
line vty 0 4
login
!
end
R4#
R7>en
R7#sh runn
Building configuration...
Current configuration : 632 bytes
!
version 12.2
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname R7
!
!
clock timezone EST -5
ip subnet-zero
!
!
!
!
interface Ethernet0/0
ip address 172.17.4.7 255.255.255.0
no keepalive
!
interface Serial1/0
no ip address
shutdown
no fair-queue
!
interface Serial2/0
no ip address
shutdown
!
interface Serial3/0
no ip address
shutdown
!
interface Serial4/0
ip address 172.17.2.7 255.255.255.0
no ip split-horizon
!
router rip
version 2
network 172.17.0.0
!
ip classless
no ip http server
ip pim bidir-enable
!
!
!
line con 0
line aux 0
line vty 0 4
login
!
end
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