Category: OSPF
Redistribution into OPSF without subnets keyword
Posted by Divin John in Cisco *STUFF*, OSPF, RIP, Routing Wednesday, 6 May 2009 11:33 No Comments
When we try to redistribute say RIP into the OSPF domain we usually give
router ospf 1
redistribute rip subnets
Ever wondered what happens when you dont give the subnets keyword?
As a matter of fact, the router tells you only classful networks are redistributed.
So, to sum up this fact say we have the following networks in RIP, being redistributed to OSPF domain
10.0.0.0/8 will be redistributed
10.2.2.0/24 will NOT be redistributed
172.16.0.0/16 will be redistributed
172.16.12.0/24 will NOT be redistributed
192.168.1.0/24 will be redistributed
192.168.2.0/30 will NOT be redistributed
I hope things are clear else unicast me @ divin<NOSPACE>john AT gmail DOT com
Redistribution: RIP,OSPF,EIGRP
Posted by Divin John in Cisco *STUFF*, EIGRP, OSPF, RIP, Routing Monday, 13 April 2009 21:31 No Comments
We have 6 Routers in this topology.
Tasks to accomplish
1) Make layer-2 connectivity and assign IP addresses to the loopback interfaces.
2) Redistribute mutually between EIGRP, RIP and OSPF
3) Make sure that the traffic to the 1.1.0.0/22 from R2 and R3 goes via the shortest path ie thru s0/0 of R2 and R3.
4) Traffic from R4,R5,R6 to 1.1.0.0/22 should be routed through R2.
5) R3 and R2 shouldn’t have network 6.6.0.0/22 in their routing table.
R1#sh run
interface Loopback0
ip address 1.1.0.1 255.255.255.0
ip ospf network point-to-point
!
interface Loopback1
ip address 1.1.1.1 255.255.255.0
ip ospf network point-to-point
!
interface Loopback2
ip address 1.1.2.1 255.255.255.0
ip ospf network point-to-point
!
interface Serial0/0
ip address 12.1.1.1 255.255.255.252
serial restart-delay 0
clock rate 64000
!
interface Serial0/1
ip address 13.1.1.1 255.255.255.252
serial restart-delay 0
clock rate 64000
!
interface Serial0/2
no ip address
shutdown
serial restart-delay 0
!
interface Serial0/3
no ip address
shutdown
serial restart-delay 0
!
router rip
version 2
network 1.0.0.0
network 12.0.0.0
network 13.0.0.0
no auto-summary
!
ip http server
no ip http secure-server
!
!
OSPF:auto-cost reference-bandwidth
Posted by Divin John in Cisco *STUFF*, OSPF, Routing Sunday, 5 April 2009 05:40 No Comments
To control how OSPF calculates default metrics for the interface, use the auto-cost command in router configuration mode. To assign cost based only on the interface type, use the no form of this command.
auto-cost reference-bandwidth ref-bw
no auto-cost reference-bandwidth
Defaults
100 megabits per second
Command Modes
Router configuration
In Cisco IOS Release 10.3 and later, by default OSPF will calculate the OSPF metric for an interface according to the bandwidth of the interface. For example, a 64K link will get a metric of 1562, and a T1 link will have a metric of 64.
The OSPF metric is calculated as ref-bw divided by bandwidth, with ref-bw equal to 108 by default, and bandwidth determined by the bandwidth command. The calculation gives FDDI a metric of 1.
If you have multiple links with high bandwidth (such as FDDI or ATM), you might want to use a larger number to differentiate the cost on those links.
The value set by the ip ospf cost command overrides the cost resulting from the auto-cost command.
Examples
The following example changes the cost of the FDDI link to 10, while the gigabit Ethernet link remains at a cost of 1. Thus, the link costs are differentiated.
router ospf 1
auto-cost reference-bandwidth 1000