Neighbour Formation Stages in OSPF

Previous post about OSPF... click here open-shortest-path-first.

Neighbour Formation Stages in OSPF

1. Down stage	It is attempt stage/ starting stage         This is the first OSPF neighbour state. It means that no information (hellos) has been received from this neighbour, but hello packets can still be sent to the neighbour in this state.
2. Init	This state specifies that the router has received a hello packet from its neighbour, but the receiving router's ID was not included in the hello packet. When a router receives a hello packet from a neighbour, it should list the sender's router ID in its hello packet as an acknowledgment that it received a valid hello packet.
3. 2-Way stage	This state designates that bi-directional communication has been established between two routers. Bi-directional means that each router has seen the other's hello packet.        At tilohe end of this stage, the DR and BDR for broadcast and non-broadcast multi-access networks are elected.

OSPF (Open Shortest Path first)

OSPF

• It is works on Dijkstra Algorithm
•  It is purely a classless protocol
• It supports only VLSM
• It is a 2-layer hierarchy
• Minimizing the routing updates traffic
•  With in the Area only all the information will send to all routers in that area (LSA)
• The ABR will send Auto summary information to the backbone area ( So burden will reduced on the main system)
• The Multi-cast address are

• 224.0.0.5 - All other routers will communicate through this Multicast address.
•  224.0.0.6 - All routers with DR router will communicate through this.
•  NOTE: DR and BDR will Understand both packets from 224.0.0.5/6

• Its AD value is 110
• Its protocol number is 89
• Metric is calculated by using “ BANDWIDTH”
•  Cost of path =  Reference Bandwidth/My outgoing link BW
•  Note: Reference BW in OSPF is 100 Mbps ( We can also change the Reference BW)
•  EX: Serial – 1.54 Mbps = 64 cost, Fast Ethernet - 100Mbps = cost 1, Ethernet – 10Mbps = cost 10

LDAP Configuration

Scenario:  Our aim is to configure the firewall such that all users should be authenticated through the LDAP server placed in our local network.

Step 1>

Configure the basic LAN and WAN settings on the Firewall.

Unified threat management

UTM features

To use UTM features you have to purchase the UTM license and apply it to your device

We first have to configure the basic LAN and WAN settings on the Firewall.

File blocking

1.      Go to UTMàAntivirusà click on Create New

2.      Give the name and then click OK,  then again click on Create New

Passive Interface and Stuck in Active concepts in EIGRP

Stuck in Active:

When a router lost any one route (route went down) then it will start query about that down route to the neighbor routers. And the neighbor router will send query to next and so on until they get reply about that route. During this mean time all routers went too stuck in active mode.

STUB Router is used to eliminate this stuck in active problem. Stub router won’t receive query, reply to query etc.

#router eigrp 100

#eigrp stub

NOTE:

Ø  Stub router won’t send the redistributed routes from any router to other

# eigrp stub redistribute                     (won’t work)

Enhanced Interior Gateway Routing Protocol

EIGRP (Enhanced Interior Gateway Routing Protocol) it is derived from IGRP

IGRP is a Distance vector routing protocol.

·         EIGRP is a Hybrid (or) Advance distance vector routing protocol

·         The AD value of EIGRP is

·         90     (EIGRP-INTERNAL),

·          170     (EIGRP-EXTERNAL)

·         Protocol  number is 88

·         It works on RTP (Reliable transport protocol)

·         It is fast convergence

·         It works as class full/ classless (no auto summary)

·         It works on AS number  (Autonomous system)  {in order to form neighbor ship the AS number should match}

·         Fast convergence

·         100% loop Free

Policy based routing (PBR)

Scenario: Our aim is to configure the firewall such that all the traffic from 192.168.1.52 will flow from WAN2 and the remaining will flow from WAN1.

RIP (Routing Information Protocol)

Rip is a distance vector protocol

•  How far and in which direction the route presents (no:of Hops between the source and destination)

Distance vector protocol:

The name distance vector is derived from the fact that routes are advertised as vectors of (distance, direction), where distance is defined in terms of a metric and direction is defined in terms of the next-hop router. For example, "Destination A is a distance of 5 hops away, in the direction of next-hop router X." As that statement implies, each router learns routes from its neighboring routers' perspectives and then advertises the routes from its own perspective. Because each router depends on its neighbors for information, which the neighbors in turn may have learned from their neighbors, and so on, distance vector routing is sometimes facetiously referred to as "routing by rumor."

1.      In rip max hop count is 15
2.      Rip AD value is 120
3.      It runs on UDP
4.      Protocol number 520

Dynamic Routing & Administrative Distance (AD)

Dynamic Routing is again subdivided into two types:

a)      IGP – it will exchange private network information within the AS

b)      EGP – it will exchange public network information within the AS

Exterior Gateway Protocol (EGP)                       Interior Gateway Routing Protocol (IGP)

* BGP (Border Gateway Protocol)                             * RIP (Routing Information Protocol)

* EIGRP (Enhanced Interior Gateway Routing Protocol)

* OSPF (Open Shortest Path First)

                       

Administrative Distance (AD Values):

Depends on the AD value router will prefer the Routes (Thrust worthiness)

Routing Basics

Routing:

The procedure of connecting two or more different networks

(Or)

The procedure of define routes, protocols and to find best path in them by using algorithms and provide security.

Routing protocol:

It is used to determine the best path for the packets are data to travel from source to destination

Routed protocol:

Which carries the data in the established path is called Routed Protocol. Routed protocols are always assigned to an interface and determine the method of packet delivery.

Ex of routed protocols is TCP, UDP, IP, IPX, SPX, Apple talk.

Different Modes in a router & Booting Sequence

Different Types of Modes in a router:

1. User Mode à Router>
2. Privilege Mode à Router#
3. Global configuration Mode à Router(Config)#
4. Interface Global configuration Mode/ Interface Mode à Router(config-if)#
5. Line Mode à #Line Vty

   Line Modes:

   à Auxiliary mode

   à Console mode Vty - Used for Telnet & SSH

Setup for ISP Failover

  

Scenario: We want to create a network in which if one ISP fails the traffic should go through the   second ISP without our network going down.

VIP (Dynamic IP Pool)

Scenario: Configure the DIP Pool on firewall so that all users behind the firewall will be accessing internet using any IP address in the DIP pool.

VIP (Mapped IP) Configuration

Our aim is to access the server remotely using Static IP mapped to local machine.

VIP (Virtual IP – Port Forwarding)

Scenario: We have hosted a machine in the network with http (Port 80) and https (Port 443) running on it. When a remote machine will access the port 8080 it will be forwarded to port 80 to the hosted machine and port 1443 would be forwarded to 443 to the hosted machine

Service Based Access (Port Blocking)

Scenario: We have to configure firewall such that computers can access only limited number of service to the internet.