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.