Chapter 8: Routing Flashcards

1
Q

Router

A

Any piece of hardware or software that forwards packets based on their destination IP address.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Routing Table

A

A list of paths to various networks required by routers.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What two fields of a routing table are used to determine the route needed?

A

Destination LAN IP and Subnet Mask

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What two fields of a routing table tell the router what to do with the packet?

A

Gateway (for IP of next hop)
and
Interface (for port to use)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

If the network ID is directly connected, then the gateway field of the routing table gets set to _________

A

0.0.0.0
or
IP address of port you’re sending to

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Command to see your routing table in Linux/OSX

A

netstat -r

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Metric

A

A relative value that defines the cost of using this route. (Lowest routes win)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Network Address Translation (NAT)

A

A means of translating a system’s IP address into another IP address before sending it out to a larger network.
Gives individual systems private IPs, and hides them behind the public IP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Port Address Translation (PAT)

A

Form of NAT that uses port numbers to map traffic from specific machines in the network.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

NAT Translation Table

A

Special database in a NAT router that stores destination IP addresses and ephemeral source ports from outgoing packets and compares them against returning packets.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Static NAT (SNAT)

A

Maps a single routable (public) IP address to a single machine, allowing you to access that machine from outside the network.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Port Forwarding

A

Preventing the passage of any IP packets through any ports other than the ones prescribed by the system administrator.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Dynamic NAT (DNAT)

A

Type of NAT in which many computers can share a pool of routable IP addresses that number fewer than the computers.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Static Route

A

An entry in a router’s routing table that is not updated by any automatic route discovery protocols.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Hop

A

Each time a packet goes through a router

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Possible Criteria for Determining a Metric

A

1) Hop
2) Bandwidth
3) Latency
4) Cost
5) Maximum Transmission Unit (MTU)
6) Shortest Path Bridging (SPB)
7) Administrative Distance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Fragmentation

A

When a packet is too big and it’s broken into pieces.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Distance Vector

A

Routing protocols that calculate the total cost to get to a particular network ID and compare that cost to the total cost of all other routes to get to that same network. It chooses the route with the lowest cost.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Convergence

A

When routers using distance vector protocols continue sending their routing tables to each other, but the routing tables don’t change.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What size of network is distance vector good for?

A

Smaller networks with less than 10 routers or so.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Routing Information Protocol (RIP)

A

Distance vector routing protocol that dates from the 1980s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Autonomous System (AS)

A

One or more networks that are governed by a single dynamic routing protocol, which provides routing for the Internet backbone.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

AS Number

A

32 bit number displayed as two 16 bit numbers separated by a dot.

24
Q

Exterior Gateway Protocols (EGP)

A

The protocols AS’s use to communicate with each other

25
Q

Interior Gateway Protocols (IGP)

A

The protocols that networks within an AS use to communicate

26
Q

Border Gateway Protocol (BGP)

A
  • An exterior gateway routing protocol that enables groups of routers to share routing information so that efficient, loop-free routes can be established.
  • Hybrid or path vector routing protocol
27
Q

Edge-routers

A

The routers that handle AS-to-AS routing

28
Q

Route Aggregation

A

A way to simplify routing tables into manageable levels. Basically a tiering system, like a tree.

29
Q

Link State

A

Type of dynamic routing protocol that announces only changes to routing tables, as opposed to the entire routing tables.

30
Q

Open Shortest Path First (OSPF)

A

An interior gateway routing protocol developed for IP networks based on the link state algorithm.

31
Q

When you first launch OSPF-capable routers, they send out _________ called Hello packets looking for other OSPF routers

A

Link State Advertisements (LSAs)

32
Q

What is the routing protocol of choice for most large enterprise networks?

A

OSPF

33
Q

Flooding

A

When a new router is sending a lot of LSAs

34
Q

Formula for hop cost in OSPF

A

100,000,000/(bandwidth in bps)

35
Q

Area

A

A group of logically associated OSPF routers designed to maximize routing efficiency while keeping the amount of broadcast traffic well managed.

36
Q

Area ID

A

Address assigned to routers in an OSPF network to prevent flooding beyond the routers in that particular network.

37
Q

When you interconnect multiple areas, what is the area id of the backbone?

A

0 or 0.0.0.0

38
Q

Route Redistribution

A

When a multiprotocol router learns route info using on protocol and announces that info using another routing protocol.

39
Q

Intermediate System to Intermediate System (IS-IS)

A

A protocol similar to OSPF, but with support for IPv6 since inception.

40
Q

Enhanced Interior Gateway Routing Protocol (EIGRP)

A

Cisco’s proprietary hybrid protocol that has elements of both distance vector and link state routing.

41
Q

Yost Cable

A

A cable used to interface with a Cisco device

42
Q

Managed Device

A

Networking devices, such as routers and advanced switches, that must be configured to use.

43
Q

Network Management Software (NMS)

A

Tools that enable you to describe, visualize, and configure an entire network.

44
Q

Basic Router Configuration Process

A

1) Set up the WAN side
2) Set up the LAN
3) Establish Routes
4) Configure a Dynamic Protocol

45
Q

When packets aren’t getting to the places you expect them, check the __________.

A

routing table

46
Q

Preventing Routing Loops

A

Split horizon

Poison reverse

47
Q

Split horizon

A

Prevents a route learned on one interface from being advertised back out of that same interface

48
Q

Poison reverse

A

Causes a route received on one interface to be advertised back out of that same interface with a metric considered to be extremely high

49
Q

Routing Protocols

A

▪ Interior Gateway Protocols (IGP)
Operate within an autonomous system

▪ Exterior Gateway Protocols (EGP)
Operated between autonomous systems (AS)

50
Q

(OSPF)

Open Shortest Path First

A

▪ Link-state protocol using cost

▪ Cost is based on link speed between routers

▪ Interior Gateway Protocol

51
Q

Routing Information Protocol (RIP)

A

▪ Distance-vector protocol using hop count

▪ Maximum hops of 15, 16 is infinite

▪ Oldest dynamic routing protocol, provides updates every 30 seconds

▪ Easy to configure and runs over UDP
▪ Interior Gateway Protocol

52
Q

Intermediate System to Intermediate System (IS-IS)

A

▪ Link-state protocol using cost

▪ Cost is based on link speed between two routers
▪ Functions like OSPF protocol, but not as popular or widely utilized
▪ Interior Gateway Protocol

53
Q

Enhanced Interior Gateway Routing Protocol (EIGRP)

A

▪ Interior Gateway Protocol
▪ Advanced distance-vector protocol using bandwidth and delay making it a hybrid of distance-vector and link-state
▪ Proprietary Cisco protocol that is popular in Cisco-only networks

54
Q

Border Gateway Protocol (BGP)

A

▪ External Gateway Protocol
▪ Path vector using the number of autonomous system hops instead of router hops
▪ Widespread utilization, this protocol runs the backbone of the Internet
▪ Does not converge quickly, though, when the topology changes

55
Q

Route Believability

A

Directly connected network - 0

Statically configured network - 1

EIGRP - 90

OSPF - 110

RIP - 120

External EIGRP - 170

Unknown or Unbelivable - 255