rip1
RIP1
What is the difference between RIPv1 and RIPv2? RIPv1 is a classful routing protocol and RIPv2 is classless.
List similar non IP routing protocols to RIP (ex. From Xerox, Novell, etc.)? Similar protocols to IP RIP are: Xerox Network Systems protocol suite (XNS), Novell’s IPX RIP, and AppleTalk’s Routing Table Maintenance Protocol (RTMP).
What is the UNIX implementation of RIP? any UNIX distributions are based on the popular 4.2 BSD (Berkeley Software Distribution) and implement RIP in either Routed or gated daemons.
From which port RIP operate? the RIP process operates from UDP port 520. All RIP messages are encapsulated in a UDP segment with both the Source and the Destination port fields set to 520
What is the metric used by RIP and what are its values? RIP uses hop count, with 1 signifying a directly connected network of the advertising router and 16 signifying an unreachable network.
How does the RIP process operate for the first time (on start-up) on a given router? On start-up, RIP enabled router broadcasts a packet carrying a RIP Request on each RIP enabled interfaces, then the rip process enters a loop, listening for RIP Request or RIP Response messages from other routers.
What happens if a router receives continuously an advertised hop count higher than the recorded hop count and the update was originated by the same recorded next-hop router? The router marks the network as unreachable for a specified holddown period. If this time expires and the same neighbor is still advertising the higher hop count, the new metric will be accepted.
What is the destination address of the RIP update messages, is it always the same or not? The destination address is all-hosts broadcasts 255.255.255.255, unless there is not broadcast media. In this case, updates are sent to directly connected neighbor on point-to-point links.
By using Ethereal software try to capture RIP update messages from a Cisco Router and identify their periodicity? Why this timer is used? IP adds a small random variable to the update timer at each reset to help avoid route table synchronization. The RIP updates from Cisco Routers vary from 25.5 and 30 seconds.
What are the main RIP timers? Update timer (between 25 to 35 seconds), Expiration time, often called timeout or Invalid timer (180 seconds), the Garbage Collection or Flush timer (set to 240 seconds), and a Cisco specific Holdown timer (180 seconds).
Is feasible to change the timing of one router in a RIP domain without changing the timers of all the routers? By which Cisco command? The RIP timers should not be changed from their default values. If the timing is changed in one router, the timing of all other routers must be changed. The command is timers basic update invalid holddown flush
What is a silent host in RIP? How to activate that in a UNIX host? It is possible that some hosts employ RIP in a silent mode and thus they do not generate RIP updates, but listen for them and update their internal route table accordingly. The command (routed –q) activate the silent mode on a UNIX host.
What is a passive-interface command? It is an IP command that makes a router a silent host on the data link specified. How many route entries does an RIP message contain? 25 routes.
Which subnet masks a RIP router uses to determine the exit routes? A RIP router uses the subnet mask of the connecting interfaces. All subnet masks with a major, class-level network must be consistent.
How does a RIP process interpret the subnet of a major network (Class A, B, or C) if it has no interfaces attached to that network? In such case, the router needs only a single route entry pointing toward a router that is directly attached.
Does a RIP router at the boundary of two major networks (such as a Network with Class A, and another of class C), advertise the subnets of one network to routers within the other network? The boundary router does not send details of the subnets of one major network into the other major network. It automatically performs summarization.
Who to configure unicast updates between two adjacent routers? Unicast updates are configured by the addition of a neighbor command under the rip process (with the IP address of the interface of the attached neighbor router) in conjunction to the passive-interface to prevent broadcast updates.
How does a route metric could be manipulated? The route metrics can be manipulated with the Cisco offset-list command.
How to minimize the routing updates if you are paying for traffic traversing low bandwidth link? By using the interface command ip rip triggered on the two interfaces of the neighbor routers (example a serial link). Updates are exchanged only when changes to the route tables occur.