eigrp auto-summary

Hi group,
I'm analyzing eigrp auto-summary behavior with a minilab of 3 routers, and
I'm surprised about the result.

Topology:
R1[f0/0]------[f0/0]R2[f0/1]------[f0/1]R3

IP plan:
R1[Lo0]: 192.168.1.1/32
R1[f0/0]: 192.168.100.1/30
R2[Lo0]: 192.168.2.2/32
R2[f0/0]: 192.168.100.2/30
R2[f0/1]: 192.168.200.1/30
R3[Lo0]: 192.168.3.3/32
R3[f0/1]: 192.168.200.2/30

auto-summary enabled on R2, disabled on R1 and R3:

R2
router eigrp 100
 network 192.168.0.0 0.0.255.255
 auto-summary

R1, R3
router eigrp 100
 network 192.168.0.0 0.0.255.255
 no auto-summary

Looking at routing table on R3, R2:Lo0 is summarized by R2, subnet between
R1&R2 is summarized by R2, R1:Lo0 is not summarized.

     192.168.200.0/30 is subnetted, 1 subnets
C 192.168.200.0 is directly connected, FastEthernet0/1
     192.168.1.0/32 is subnetted, 1 subnets
D 192.168.1.1 [90/435200] via 192.168.200.1, 01:40:21, FastEthernet0/1
D 192.168.2.0/24 [90/409600] via 192.168.200.1, 01:40:21, FastEthernet0/1
D 192.168.100.0/24 [90/307200] via 192.168.200.1, 01:40:21,
FastEthernet0/1
     192.168.3.0/32 is subnetted, 1 subnets
C 192.168.3.3 is directly connected, Loopback0

What i see, is that R2 performs auto-summarization only for connected
network.
Can you explain why R1:Lo isn't summarized by R2, or provide a link?

Cisco-doc said: "EIGRP performs an auto-summarization each time it crosses a
border between two different major networks", but this doesn't match with
the above result.

thanx,
mirco.

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Received on Wed May 19 2010 - 14:24:34 ART