The experience of forgetting information that you trust a digital device to store and remember for you
1.5.c i Attribute manipulation In BGP, there are two main options to manipulate the Weight attribute: per-neighbor basis per-prefix basis. Note: The BGP’s Weight Path attribute is the first path attribute BGP checks in the election of the best path in the BGP table on Cisco IOS Routers. BGP prefers the path for the entry… read more »
EIGRP summarization Summarization can be employed on any router in an EIGRP network, since it is a distance-vector protocol and does not keep a LSDB on all routers on the network. Summary routes in EIGRP have an AD value of 5. The summary router will advertise the summary route with an outgoing interface of Null0… read more »
There are a number of different packet types used by OSPF these are typically Hello packets, and the different LSA types; LSA Type 1 Router LSA The router will announce its presence and list the links to other routers/networks in the same area along with metrics to them. Type 1 LSAs do not cross into… read more »
Network Types OSPF network types control: How hellos and updates are sent Who forms an adjacency How the next-hop is calculated Point-to-Point The simplest network type. As the name suggests is simply a link between two routers. A packet sent from one router, can only ever go to the one recipient on a point-to-point network. … read more »
OSPF discovers and maintains neighbor relationships by using Hello packets. These are sent at regular intervals on interfaces participating in the OSPF routing process. Hello packets are sent to the multicast address 224.0.0.5 (IPv6 FF02::5). The two timers used are: Hello interval: this defines how often we send the hello packet. Dead interval: this defines… read more »
1.3.c i General operations Here’s a quick overview of EIGRP: Distance-vector routing protocol. Transport is IP protocol 88 (does not use TCP or UDP). Also implements it’s own Reliable Transport Protocol (RTP). Hello Timer – Interval at which Hello messages are sent out an interface. Hold Timer – Used to determine when a neighbor has… read more »
EIGRP’s operations can be conceptually simplified into three basic steps: Step 1. Neighbor Discovery: Through the exchange of Hello messages, EIGRP-speaking routers discover one another, compare parameters (for example, autonomous system numbers, K-values, and network addresses), and determine if they should form a neighborship. Step 2. Topology Exchange: If neighboring EIGRP routers decide to form… read more »
OSPF Basic OSPF supports adjacency authentication to protect control plane E.g. prevent against routing injection attack Every OSPF packet header includes authentication information I.e. Hello, LSU, LSR, etc. Authentication does not mean encryption OSPFv2 payload is still clear text OSPFv3 supports IPsec encryption Types of authentication (3) Type 0 – Null Type 1 – Simple… read more »
1.3d i Equal-cost EIGRP will load balance 4 equal cost paths into the routing table by default. Traffic is shared equally between each path. The number of paths is configurable using the command: max-paths <[1-6]>. Configuration Verification 1.3d ii Unequal-cost EIGRP allows for unequal cost load balancing using the variance command where variance is a… read more »
1.3b i RD, FD, FC, successor, feasible successor RD Reported Distance, the total metric along a path to a destination network as advertised by an upstream router. FD Feasible Distance, the best metric along a path to a destination, includes metric to the neighbour advertising the path. Lowest calculated metric to each destination. FC Feasibility… read more »