Router Functions

Question 1

What are the key functions of a router?

Answer 1

• routing mechanism
• dynamic routing support
• process program

Question 2

What is the method for a routing mechanism?

Answer 2

Table search method

Question 3

Routers provide dynamic support for what four things?

Answer 3

• RIP, OSPF, EGP, BGP
• information exchange protocols
• routers that send and receive info from other routers
• router table copy

Question 4

What are the two types of process programs?

Answer 4

• routed daemon

- gated daemon for UNIX

Question 5

What do routed and gated daemon for UNIX do?

Answer 5

apply routing policy: what to change, add, or subtract on the table

Question 6

T/F: RIP is an Interior Gateway Protocol.

Answer 6

True

Question 7

T/F: RIP is a distance vector/link state protocol.

Answer 7

False. Distant vector, not link state.

Question 8

What does RIP contribute to?

Answer 8

Updating routing tables. Routers send all or part of their routing tables to their neighbours.

Question 9

What do routing table updates contain?

Answer 9

• destinations
• next hop IP addresses
• hop count metrics

Question 10

T/F: RIP is suited for large networks because it uses little bandwidth.

Answer 10

False. RIP is better suited to small networks where it is easy to implement and maintain.

Question 11

How often do routers update their neighbours?

Answer 11

Every 30 seconds.

Question 12

When was RIPv1 implemented and what were its limitations?

Answer 12

• before 1988
• high overhead
• supports standard subnetting
• slow convergence
• no support for EGP and BGP
• simple metric
• metric limited to 15

Question 13

When was RIPv2 implemented and what are its highlights?

Answer 13

1993, updated in 1994

• resolved RIPv1 limitations except for small metric (intended for a small network)
• supports subnetting
• supports EGP/BGP
• supports multiple routing daemons
• supports a next-hop address option
• supports an authentication scheme
• supports multicasting and broadcasting

Question 14

What are limitations for RIPv2?

Answer 14

• simplicity makes it better for small network
• simple metric
• metric limited to 15
• high overhead

Question 15

Metric limited to 15 means what?

Answer 15

The maximum hop count is 15. 15 is the number of hops, no more and no less. Thou shalt not hop to 16, neither shou thou hop to 14 unless followed by 15… no, wait, you can hop to 14.

Question 16

The Bellman-Ford algorithm is the basis for what?

Answer 16

The Distance Vector Protocol.

Question 17

When is a route marked for deletion?

Answer 17

When a router notices a lack of table entry advertisement for 3 minutes. The route deletion is delayed through an update or something.