Stream of Knowledge

 Why do we need i-BGP for the routes when we have the IGP protocols (OSPF, IS-IS) for internal communication within the AS? IGPs like OSPF or ISIS, are link-state protocols that give us all the information of the network and allow for very interesting convergence options and traffic engineering options. Whereas, BGP knows a very limited view of the network as a whole because BGP handles very well filtering and modifying routing information. See, the traffic in a network can be divided into 4 categories. • Ingress: traffic arriving from outside the network, destined for hosts within the network. • Egress: traffic originating inside the network destined for hosts outside the network. • Internal: traffic where both the origin and destination are within the network. • Transit: traffic where both the origin and destination are outside the network. The IGP normally carries internal routes, so it can be used to directly route ingress and internal traffic, but what about egress and transit...

  OSPF Multi-Area Configurationg We will use the following topology: Above we have R1 and R2 in area 0, the backbone area. Between R1 and R3, we will use area 1 and between R2/R4 we will use area 2. R3 and R4 have a loopback interface with an IP address that we will advertise in their area. Configuration Let’s start with all network commands to get OSPF up and running. The network command defines to which area each interface will belong.First, we will configure R1 and R2 for the backbone area: R1(config)# router ospf 1 R1(config-router)# network 192.168.12.0 0.0.0.255 area 0 R2(config)# router ospf 1 R2(config-router)# network 192.168.12.0 0.0.0.255 area 0 Let’s configure R1 and R3 for area 1: R1(config)# router ospf 1 R1(config-router)# network 192.168.13.0 0.0.0.255 area 1 R3(config)# router ospf 1 R3(config-router)# network 192.168.13.0 0.0.0.255 area 1 R3(config-router)# network 3.3.3.3 0.0.0.0 area 1 And last but not least, R2 and R4 for area 2: R2(config)# router ospf 1 ...

 Find below the configurations for route redistribution between OSPF and EIGRP LAB.   R1 configurations: configure terminal interface serial 1/1 ip address 4.1.1.2 255.0.0.0 no shut interface serial 1/0 ip address 1.1.1.1 255.0.0.0 no shut interface fastethernet 0/0 ip address 200.100.50.100 255.255.255.0 no shut router ospf 11 network 1.0.0.0 0.255.255.255 area 0 network 4.0.0.0 0.255.255.255 area 0 network 200.100.50.0 0.0.0.255 area 0 network 200.100.200.0 0.0.0.255 area 0 redistribute eigrp 10 subnets exit router eigrp 10 redistribute ospf 11 metric 1 1 1 1 1 R2 configurations: configure terminal interface serial 1/0 ip address 1.1.1.2 255.0.0.0 no shut interface serial 1/1 ip address 2.1.1.1 255.0.0.0 no shut interface fastethernet 0/0 ip address 200.100.100.100 255.255.255.0 no shut router ospf 11 network 1.0.0.0 0.255.255.255 area 0 network 4.0.0.0 0.255.255.255 area 0 network 200.100.50.0 0.0.0.255 area 0 network 200.100.200.0 0.0.0.255...

 #ospf #protocol #configuration #lab #DR #BDR Lab objectives: Ensure router R1 is the DR for network 100.1.1.0 /24. Ensure router R3 is the BDR for network 100.1.1.0 /24. Ensure router R5 is the DR for network 100.1.2.0 /24. without changing the priority Ensure router R2 is the BDR for network 100.1.2.0 /24. You are not allowed to change the priority. Solution configurations: R1: conf t int fa 0/0 ip address 100.1.1.2 255.255.255.0 no shutdown exit router ospf 10 network 100.1.1.0 0.0.0.255 area 0 network 100.1.2.0 0.0.0.255 area 0 log-adjacency-changes conf t router ospf 10 log-adjacency-changes exit exit R2: the solution to achieve all objectives: change priority of R1 must be higher than R3 change priority of R2 must be lower than R1 change router-id manually to higher router ID 120.120.120.2