Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
20 Cards in this Set
- Front
- Back
|
What arguments does the "ip route" command expect?
|
[subnet number] [netmask] [next-hop ip]
|
|
|
How do you configure a static route on a serial point-to-point interface?
|
ip route [subnet no.] [netmask] [interface]
|
|
|
Define route poisoning.
|
When a router notices that a link is down, instead of not advertising that route anymore, it advertises it with an infinite metric.
|
|
|
Define split horizon.
|
Routes are not advertised out the interfaces on which they were learned.
|
|
|
Define split horizon with poison reverse.
|
The routing protocols use split horizon rules unless a route fails, in which case the route is advertised with an infinite metric out ALL interfaces, including the one on which it was learned.
|
|
|
Define hold-down timer.
|
After finding out that a route to a subnet has failed, a router waits a certain amount of time before believing any other routing information about that subnet.
|
|
|
Define triggered updates.
|
When a route fails, an update is sent immediately rather than waiting for the next scheduled time. Used in conjunction with route poisoning, this ensures that all routers know of failed routes before any hold-down timers can expire.
|
|
|
How long is the default hold-down timer in RIP? What about IGRP?
|
30 seconds in RIP, 90 seconds in IGRP.
|
|
|
How do you enable RIP on a router?
|
router rip
|
|
|
How do you configure which routes are advertised and which interfaces participate in RIP?
|
network [network no]
|
|
|
How do you enable IGRP on a router?
|
router igrp [as number]
|
|
|
What is an AS number?
|
Autonomous System Number - used to identify a group of devices that will share IGRP information.
|
|
|
How does RIP calculate a metric for each route?
|
0 for directly connected, +1 for every router between itself and the network.
|
|
|
How does IGRP calculate a metric for each route?
|
Function of bandwidth, delay, load, reliability, and MTU. Usually only bandwidth and delay are considered.
|
|
|
How does a router know the bandwidth for each interface?
|
On LAN interfaces, the router uses the correct default bandwidth value. On serial interfaces, 1544 is used by default (1.544 Mbps = T1). The "bandwidth" subcommand can set these values manually too.
|
|
|
If RIP places more than 1 valid route to the same subnet in the routing table, how does it decide which route to use?
|
It balances traffic between them.
|
|
|
If IGRP places more than 1 valid route to the same subnet in the routing table, how does it decide which route to use?
|
It uses the variance subcommand to define how close metrics need to be in order for the routes to be considered "equal". Then it balances traffic between them in proportion to their metrics.
|
|
|
How could you override the default traffic balancing feature for IGRP?
|
traffic-share min
|
|
|
What is administrative distance?
|
A value given to each routing protocol that denotes how "believable" that routing protocol is. So if multiple routing protocols learn routes to the same subnet, the IOS software knows which route to use.
|
|
|
What is the difference between an exterior routing protocol and an interior routing protocol?
|
Exterior routing protocols like BGP are used between two organizations. Interior routing protocols like RIP and IGRP are used within a single organization.
|
