Dynamic Routing Protocols

1: What is a routing protocol?

* A routing protocol is a "language" that routers speak to each other to share information about network destinations.

2: What basic procedures should a routing algorithm perform?

* At a minimum, a routing protocol should define procedures for:Passing reachability information about networks to other routersReceiving reachability information from other routersDetermining optimal routes based on the reachability information it has and for recording this information in a route tableReacting to, compensating for, and advertising topology changes in an internetwork

3: Why do routing protocols use metrics?

**A route metric, also called a route cost or a route distance, is used to determine the best path to a destination. Best is defined by the type of metric used.

4: What is convergence time?

* Convergence time is the time a group of routers take to complete the exchange of routing information.

5: What is load balancing? Name four different types of load balancing.

* Load balancing is the process of sending packets over multiple paths to the same destination.Four types of load balancing are:
a) Equal cost, per packet
b) Equal cost, per destination
c) Unequal cost, per packet
d) Unequal cost, per destination

RIP , Q & A part ----II

6: Why is a random timer associated with triggered updates? What is the range of this timer?

* The random timer, whose range is 1 to 5 seconds, prevents a "storm" of triggered updates during a topology change.

7: What is the difference between a RIP Request message and a RIP Response message?

* A Request message asks a router for an update. A Response message is an update.

8: Which two types of Request messages does RIP use?

* A Request message may either ask for a full update or in some special cases it may ask for specific routes.

9: Under what circumstances will a RIP response be sent?

* A Response is sent when the update timer expires, or upon reception of a Request message.

10: Why does RIP hide subnets at major network boundaries?

** RIP updates do not include the subnet mask of the destination address, so a RIP router depends on the subnet masks of its own interfaces to determine how an attached major network address is subnetted. If a router does not have an attachment to a particular major network address, it has no way to know how that major network is subnetted. Therefore, no subnets of a major network address can be advertised into another major network

Static Routing

1: What information must be stored in the route table?

* At a minimum, each entry of the routing table must include a destination address and the address of a next-hop router or an indication that the destination address is directly connected.

2: What does it mean when a route table says that an address is variably subnetted?

* Variably subnetted means that the router knows of more than one subnet mask for subnets of the same major IP address..

3: What are discontiguous subnets?

* Discontiguous subnets are two or more subnets of a major IP network address that are separated by a different major IP address.

4: What command is used to examine the route table in a Cisco router?

* show ip route is used to examine the routing table of a Cisco router.

5: What are the two bracketed numbers associated with the non-directly connected routes in the route table?

* The first bracketed number is the administrative distance of the routing protocol by which the route was learned. The second number is the metric of the route.