Routing

Routing

1. Interior Gateway Protcol

   • Distance Vector
     • EIGRP
       • Enhance Interior Gateway Routing Protocol. Cisco added some features from link-state routing protocols. Which makes it far more advance.
       • Overview
         • Advance Distance Vector. Multi & Uniicast (exchange info) Multiple network layer supported 100% Loop Free Multicast EIGRP packets for IPv4 use the reserved IPv4 multicast address 224.0.0.10
       • Neighbor Table
         • List all directly connected neighbors. Next Hop Router Interfaces.
       • TopologyTable
         • List all learned routes from all EIGRP neighbors. Destinations. Metric
       • Routing Table
         • Best routes from EIGRP topology table will copied to the routing table.
       • Metric
         • Bandwidth Delay Load Reliability
       • Features
         • Diffusing Update Algorithm As the computational engine that drives EIGRP, the Diffusing Update Algorithm (DUAL) resides at the center of the routing protocol. DUAL guarantees loop-free and backup paths throughout the routing domain. Using DUAL, EIGRP stores all available backup routes for destinations so that it can quickly adapt to alternate routes when necessary. Establishing Neighbor Adjacencies EIGRP establishes relationships with directly connected routers that are also enabled for EIGRP. Neighbor adjacencies are used to track the status of these neighbors. Reliable Transport Protocol The Reliable Transport Protocol (RTP) is unique to EIGRP and provides delivery of EIGRP packets to neighbors. RTP and the tracking of neighbor adjacencies set the stage for DUAL. Partial and Bounded Updates EIGRP uses the terms, partial and bounded, when referring to its updates. Unlike RIP, EIGRP does not send periodic updates and route entries do not age out. The term partial means that the update only includes information about the route changes, such as a new link or a link becoming unavailable. The term bounded refers to the propagation of partial updates that are sent only to those routers that the changes affect. This minimizes the bandwidth that is required to send EIGRP updates. Equal and Unequal Cost Load Balancing EIGRP supports equal cost load balancing and unequal cost load balancing, which allows administrators to better distribute traffic flow in their networks
         • Authentication
           • MD5
         • 5 differents PACKETS
           • Hello packets - Used for neighbor discovery and to maintain neighbor adjacencies. Sent with unreliable deliveryMulticast (on most network types) Update packets - Propagates routing information to EIGRP neighbors. Sent with reliable deliveryUnicast or multicast Acknowledgment packets - Used to acknowledge the receipt of an EIGRP message that was sent using reliable delivery. Sent with unreliable delivery Unicast Query packets - Used to query routes from neighbors. Sent with reliable deliveryUnicast or multicast Reply packets - Sent in response to an EIGRP query. Sent with reliable deliveryUnicast
           • Hello. Update. Ack. Querry. Reply
             • Hello packets are used for neighbor discovery. As soon as you send hello packets and receive them your EIGRP routers will try to form the neighbor adjacency. Update packets have routing information and are sent reliable to whatever router that requires this information. Update packets can be sent to a single neighbor using unicast or to a group of neighbors using multicast. Query packets are used when your EIGRP router has lost information about a certain network and doesn‟t have any backup paths. What happens is that your router will send query packets to its neighbors asking them if they have information about this particular network. Reply packets are used in response to the query packets and are reliable. ACK packets are used to acknowledge the receipt of update, query and replay packets. ACK packets are sent by using unicast.
       • Protocol - Dependent Module
         • PDM's are responsible for the specific routing tasks for each network layer protocol, including: Maintaining of EIGRP routers that belong to that protocol suite.
       • Backup Paths
         • A distance vector protocol. Doesn‟t know what the complete network looks like…it‟s not a link-state routing protocol like OSPF which DOES have a complete map of the network. Distance vector routing protocols only know which way to go (vector) and how far away the destination is (distance).
         • Succesor(main route). Feasible Succesor
       • Autonomus Sytem Number
     • RIP weakness:
       • No neighbor Discovery Periodic Updates Vulnerable to Loops. Simple metric(Hoop count)