Monday 23 July 2012

Slash Notation

- Many purpose of slash notation, one of it is policy configuration.

- It also know as CIDR(Classess Inter-Domain Routing) notation.

- CIDR is a compact way to show or write a subnet mask.

- How to use slash notation: -> <ipaddress>/<subnet mask>

- How to find subnet mask number:
1. Convert the decimal representation of the subnet mask to a binary representation.
2. Count each "1" in the subnet mask. The total is the subnet mask number.

- Example:
IP Address: 192.68.42.23
Subnet mask: 255.255.255.0

1. Convert the subnet mask to binary = 11111111.11111111.11111111.00000000
2. Count each "1" in the subnet mask = 24
3. Here the result: 192.168.42.23/24


- Table:

Open Shortest Path First (OSPF)

- An interior router protocol used in larger networks.


- A routers that sees a change to its routing table or that detect a change in the network immediately sends a multicast update to all other router in the network.

- OSPF vs. RIP
1. OSPF sends only the part of the routing table that has changed in its transmission. RIP sends the full routing tables each time.
2. OSPF sends a multicast only when its information has changed. RIP sends thee routing table every 30 seconds.


- If more than one OSPF are, one area must be area 0.0.0.0(the backbone area).

- All areas must be adjacent to the backbone area. If they are not, virtual link must be configure to the backbone area.

Routing Information Protocol (RIP)

- Used to manage router information in a self-contained network (LAN).


- Gateway host sends its routing table to the closest router each 30 seconds.


- Then send the contents of its routing tables to neighboring routers.


- Best for small networks, because the transmission of the full routing table each 30 seconds can load on the network.


- RIP tables are limited to 15 hops. 


- OSPF(Open Shortest Path First) is a better alternative for larger network.


- Two versions of RIP. 
1. RIPv1 -> uses a UDP(User Datagram Protocol) broadcast over port 520 to send updates to routing tables.
2. RIPv2 -> uses multicast to send routing table updates.


Tutorial:
1.Cisco How To Configure RIPv1
2.Cisco How To Configure RIPv2

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