From: Bhisham Bajaj (bhishambajaj@xxxxxxxxx)
Date: Sun Jan 06 2002 - 00:51:38 GMT-3
There are 5 routers
R1----------R2-----------R3----------R4------------R5
Area 1 Aear 0 Area 2 IGRP
R2 is the ABR for Area 1, there are 8 networks in Area
1
142.1.32.0/24 00100 000
142.1.33.0/24 00100 001
142.1.34.0/24 00100 010
142.1.35.0/24 00100 011
142.1.36.0/24 00100 100
142.1.37.0/24 00100 101
142.1.38.0/24 00100 110
142.1.39.0/24 00100 111
We can summarize these networks into one network with
the /21 mask
And inject it into the ospf Area 0
So on R2 we would use the command
R2(config-router)# area 1 range 142.1.32.0
255.255.248.0
So this will summarized route into Area o for networks
32 to 39
Now we have network 40 to 47 in Area 0 & Area 2
142.1.40.0/24 00101 000
142.1.41.0/24 00101 001
142.1.42.0/24 00101 010
142.1.43.0/24 00101 011
142.1.44.0/24 00101 100
142.1.45.0/24 00101 101
142.1.46.0/24 00101 110
142.1.47.0/24 00101 111
The R4 is a router in Area 2 and is the ASBR it has S0
in OSPF netork and S1 into IGRP network
OSPF s0 s1 IGRP
------------------------R4-------------------------
142.1.47.0/24 142.1.16.0/20
The OSPF network is made up of 142.1.32.0 to
142.1.47.0 /24
These routes have to be redistributed into IGRP witch
has a net work 142.1.16.0/20
The IGRP will not advertise a route with the same
major network and different mask
So we have to summarize all the ospf network into one
/20 bit network
142.1.32.0/24 0010 0000
142.1.33.0/24 0010 0001
142.1.34.0/24 0010 0010
142.1.35.0/24 0010 0011
142.1.36.0/24 0010 0100
142.1.37.0/24 0010 0101
142.1.38.0/24 0010 0110
142.1.39.0/24 0010 0111
142.1.40.0/24 0010 1000
142.1.41.0/24 0010 1001
142.1.42.0/24 0010 1010
142.1.43.0/24 0010 1011
142.1.44.0/24 0010 1100
142.1.45.0/24 0010 1101
142.1.46.0/24 0010 1110
142.1.47.0/24 0010 1111
we can summarize network 32 to 47 /24 into one network
142.1.32.0 /16
ON the ASBR that I the router R4 we will have to use
the
summary-address command so that when OSPF
redistributes route into IGRP
it will advertise the neworks 32 to 47 /24 as 32/20
R4(config-router)#summary-address 142.1.32.0
255.255.240.0
Know that the 142.1.32.0/16 advertisement is of the
same mask that is used by IGRP
The S1 interface that is in the 142.1.16.0/20 network
will
Advertise the network 142.1.32.0/16 to router R5
And R5 will be able to reach all the OSPF network with
one route in its routing table
HTH
Bhisham
This archive was generated by hypermail 2.1.4 : Thu Jun 13 2002 - 10:56:17 GMT-3