Chapter 9210.70.254.122/chingyu/Ch9 Advanced Routing Protocols.pdf · 2007. 9. 26. · EIGRP (cont.) Fig. 9-22 shows the output of the‘show ip eigrp neighbors’ command on RouterA

1

Chapter 9Advanced Routing

Protocols

2

Classful and Classless Routing ProtocolsRIP version 2EIGRP

Contents

OSPF

Review QuestionsControlling Route Traffic

3

Classful and Classless Routing Protocols

In general, distance-vector routing protocols send periodic updates of their entire routing tableto their directly connected neighbors.

4

Classful and Classless Rout. Prot. (cont.)

Whereas, link-staterouting protocols flood nonperiodic link-state advertisement of only changed routesthroughout the entire internetwork.

5


Routing protocols are also defined as either classful orclassless, terms that describe how the routing protocols handles subnet mask information in its routing table updates

6


Classful routing protocols summarize networks to their major network boundaries (Class A, B, orC) and do not carry subnet mask information to their routing table updates.

7


RIPv1 and IGRP are classfulrouting protocols; they do not carry any subnet mask information in their routing table updates. Fig. 9-1shows the update message format for RIPv1.

8


Fig. 9-2 shows an example of how different major networkseparate two subnets from the same major network, 192.168.12.0/24. This is called discontiguous subnets.

9


Fig. 9-3 shows the configuration of RIPv1 on RouterA. This will cause problems in the network in this example.

10


Fig. 9-4 shows the routing table of RouterBafter RIPv1 has been configured on just RouterA and RouterB.

11


After configuration ofRouterC with RIPv1, however, RouterB’s routing table changes quickly. Fig. 9-5 shows the two equal cost routes in RouterB’s routing table.

12


Fig. 9-6 shows a ping attempt by RouterB to 192.168.12.33 using the extended ping command.

13


As you can see, the ping work, but only intermittently. This is a result of the dual equal cost route in RouterB’srouting table.

14


Classful routing protocolscannot adopt to work in an environment where discontiguous networksor VLSM exist.

15

Classless routing protocolscan carry subnet maskinformation in the routing table updates.


RIPv2, EIGRP, OSPF and BGP are classless routing protocols. Fig. 9-7 shows RIPv2’s route update message format.

16


Converting from RIPv1 to RIPv2 is very simple. Fig. 9-8 shows the commandsto convert RouterB to RIPv2.

17


Fig. 9-9 shows RouterB’srouting table after theconversion.

18


As a result, the extended ping commandin Fig. 9-10 works correctly every time.

19


In general, due to the complexity of modern networks and the use of VLSM, most networks use classless routing protocols.

20


Contents

OSPF


21

RIP version 2

RIPv2 is not a totally new protocol. In reality, it is a set of extensionsto RIPv1 .

22

RIP-1先天的缺陷，例如，收斂時間過長、只能通過15個中繼節點、更新通告每30秒發佈一次消耗網路頻寬及只

考慮中繼節點的數目等問

題，依然存在於RIP-2。

RIP version 2 (cont.)

23

RIP-2與RIP-1的主要區別

支援變動長度子網路遮罩

(VLSM)支援認證功能(使用MD5認證機制)


更新通告採用Multicast位址(224.0.0.9)

24


Configuring RIP-2 is a simple process. Fig. 9-11shows a simple network in which two of three routersare running RIP-2 while a third router is running RIP-1.

25


Fig. 9-12 shows the commands necessary to configure RIPv2 on RouterA.

Fig. 9-13 shows that the current routing protocol is RIP and the routing updates for version 2 are being sent and received.

26


RIPv2 maintains backward compatibilitywith RIPv1. In Fig. 9-11, RouterB

must be configured to send and receive RIPv1updates to RouterC.

27


Fig. 9-14 shows a correct configuration of RouterB tosupport RIPv1 and RIPv2.

If RouterB had not been configured to send and receive version 1 updates,the errors would be appeared.(see Fig. 9-15)

28


RIPv2 authentication can occur either by passing the authentication keysin clear text or via MD5authentication.

29


RFC 1321 defines MD5 as an “algorithm that takes as input a message of arbitrary length and produces as output 128-bit‘fingerprint’ or ‘message digest’ of the input.”

30


In short, using MD5allows RIPv2 toauthenticate a routing peer without sending the secret key across the link between the two peer.

31

Fig. 9-16 shows authentication being configured on both RouterAand RouterB.


32


If authentication only configured on one of the two peers, the errors inFig. 9-17 would be displayed.

33


Fig. 9-18 shows many of features described in this section. It shows RouterBmulticasting RIPv2 updates via 224.0.0.9 to RouterA.

In addition, it showsRouterB broadcasting RIPv1updates via 255.255.255.255.

34


Contents

OSPF


35

EIGRP (Enhanced IGRP)是IGRP的加強版，它結合了距離向量(distance vector)與連結狀態 (link state)的優點，得以達到快速收斂。

EIGRP

36

EIGRP也是Cisco提出的路由協定(Cisco Proprietary Protocol) ，具有距離向量與連結狀態兩個協定的特

點，又稱為進階的距離向量

協定 (Advanced Distance -vector Protocol)。

EIGRP (cont.)

37

EIGRP 使用 DUAL (Diffusing UpdateAlgorithm)演算法，當路徑發生變化時，DUAL只會傳送更動的部份，而不是整個

路由表，因此可快速反應。

EIGRP (cont.)

38

EIGRP不會週期性傳送路由訊息，因此可以節省頻寬的

使用。

另外，EIGRP也支援多重的網路層協定，例如， IP、IPX 及AppleTalk等協定。

EIGRP (cont.)

39

To make (IGRP to EIGRP) migration simple, Cisco created a feature ofEIGRP called automatic redistribution.

EIGRP (cont.)

40

Both IGRP and EIGRPhave to be configured on the same router at the border between two protocols, and they both use the same AS number.

EIGRP (cont.)

41

Fig. 9-19 shows a network where EIGRP and IGRP automatic redistributionoccurs.

EIGRP (cont.)

RouterB is configured withboth EIGRP and IGRP using the autonomous systemnumber of 52.

42

Fig. 9-20 shows the routing table of RouterA. RouterAhas a normal EIGRP route, flagged as “D” in the routing table, and external EIGRP routes, flagged as “D EX.”

EIGRP (cont.)

43

Note that you should use the following commandson RouterB under the Boson NetSim tool.

EIGRP (cont.)

router eigrp 52redistribute igrp 52network 10.0.0.0network 172.16.0.0

44

Note that you should use the following commandson RouterB under the Boson NetSim tool. (cont.)

EIGRP (cont.)

router igrp 52redistribute eigrp 52network 10.0.0.0network 172.16.0.0

45

Here are some of main commandsyou’ll use when viewing and troubleshooting EIGRP.

Troubleshooting EIGRP

show ip protocols show ip route show ip eigrp neighborsshow ip eigrp topologyshow ip eigrp trafficdebug ip eigrp

46

Here are some of main commands used to help troubleshoot IGRP.

Troubleshooting IGRP

show ip protocols show ip route debug ip igrp eventsdebug ip igrp transactions

47

Cisco developed a entirely new layer 4 protocol, the reliable transport protocol(RTP), for use by EIGRP.

EIGRP (cont.)

RTP provides both reliable and unreliable delivery. For example, the Hello packetsare sent as unreliable multicast.

48

EIGRP (cont.)

Routing table updates are an example of an EIGRP packet type that use reliable multicast via RTP.

Reliable multicast is a feature of RTP that requiresan ACK via unicast to a multicast message.

49

EIGRP (cont.)

EIGRP packet type

50

EIGRP (cont.)

The Diffusing Update Algorithm (DUAL) is the heart and soul of EIGRP, and is the reason that EIGRP can quickly recover from a link outage and route around network problems.

51

EIGRP (cont.)

Fig. 9-22 shows the output of the ‘show ip eigrpneighbors’ command on RouterA in Fig. 9-21.

52

EIGRP (cont.)

Once neighbors have been discovered, EIGRPruns the DUAL algorithmto create EIGRP topology table.

53

EIGRP (cont.)

Using the ‘show ip eigrptopology’ command shown in Fig. 9-23, you can display informationgarnered from the DUAL process.

54

EIGRP的運作原理在EIGRP網路中，每個路由器必須維護鄰近表

(Neighbor Table)、拓樸表 (Topology Table)及路徑表(Routing Table)等三種資料。

EIGRP (cont.)

55

EIGRP的運作原理(續)鄰近表(Neighbor Table)用來記錄鄰接的路由器

拓樸表(Topology Table)用來記錄所有可到達目的地

的路徑，路由器也依此資料

來建立路徑表。

EIGRP (cont.)

56

路徑表(Routing Table)從拓樸表中，找出可到

達目的地的每條最佳路

徑稱之為Successor，而次佳的路徑稱為

Feasible Successor。

EIGRP (cont.)

EIGRP的運作原理(續)

57

路徑表(續)

請注意，路徑表中只儲

存 Successor ，而

Feasible Successor則存放在拓樸表中。

EIGRP (cont.)


58

在了解前述三個資料表後，EIGRP的運作，概述如下：建立鄰近表

發現路徑

選擇路徑

維護路徑

EIGRP (cont.)


59

建立鄰近表 (Building the Neighbor Table)使用EIGRP的路由器會先傳送Hello packets，來發現鄰近的路由器，同時更新路徑。

EIGRP (cont.)


60

發現路徑 (Discoveringroutes)基本上，發現路徑與建立

鄰近表都是使用 Hellopackets同時處理完成的。

EIGRP (cont.)


61

在運作的EIGRP網路中，Hello packets是週期性地送出(T1的預設值是5秒，WAN是60秒)，以確認鄰近的路由器仍然正常存在。

EIGRP (cont.)


62

EIGRP的運作原理(續)選擇路徑 (Choosing

routes)在EIGRP網路中，選擇路徑是從拓樸表中取出

最佳路徑放入路徑表。

EIGRP (cont.)

63

EIGRP在採用了頻寬、延遲兩項，作為最佳路徑的衡量

指標(cost)。公式如下：256 [ (10,000,000/最小頻寬) +延遲總和]

選擇路徑(續)

EIGRP (cont.)


64

EIGRP利用頻寬與延遲計算衡量指標範例一

EIGRP (cont.)

65

範例一說明

以#1路由器如何找到D網路為說明對象，分別計算經過#2路由器與#3路由器的衡量指標。

利用前述公式算出經過#2路由器的成本為46,021,376，而經#3 路由器的成本為

20,307,200。

EIGRP (cont.)

66

範例一說明(續)

因此#3路由器便為#1路由器到達D網路的最佳路徑，並加入於路由表內。

EIGRP (cont.)

67

EIGRP利用頻寬與延遲計算衡量指標範例二

EIGRP (cont.)

68

維護路徑 (Maintaining routes)是指當網路發生變動，如

新的路由器加入、路徑的

cost改變或斷線，此時，路由器就必須要另尋一條路徑。

EIGRP (cont.)


69

EIGRP (cont.)

EIGRP ConfigurationEIGRP configuration is

nearly identical to IGRP configuration. Fig. 9-26shows the commandsnecessary to configure basic on RouterA.

70

EIGRP (cont.)

EIGRP Configuration (cont.)Fig. 9-27 shows EIGRP

routes in the routing tableof RouterA. All of the EIGRProutes in this table come from EIGRP topology table.

71

EIGRP (cont.)

EIGRP Configuration (cont.)EIGRP supports optional

authentication of routing peers. However, it only supports MD5 authentication.

Fig. 9-28 shows the commands necessary onRouterA and RouterB to configure authentication.

72

EIGRP (cont.)

To provide robust routing services on multi-vendor networks, many system administrator turn to theopen standards link-state protocol called OSPF.

73

EIGRP & IGRP Similarities

EIGRP (cont.)

74

EIGRP & IGRP Differences

EIGRP (cont.)

75


Contents

OSPF


76

OSPF

Open shortest path first (OSPF) is an open standards, link-state protocol that supports classless routing, VLSM, and authentication.

77

OSPF (cont.)

Each router sends out LSAsto all routers in an area describing its attached links. These LSAs are not periodic. Instead, they are sent onlywhen a change occurs in the network.

78

OSPF (cont.)

The downside of link-state protocols comes from the need for each router hold a topological database of the entire area; this requirement increase CPU and memorydemands on a router.

79

OSPF (cont.)

Because OSPF creates an adjacencies database, topological database, and a routing table, it requires more memory to run than a simple protocol such as RIP.

80

OSPF (cont.)

Table 9-2 summarizes the main differences between distance-vector and link-state routing protocols.

81

OSPF (cont.)

OSPF is ideally suited for large networks, as it can use a concept known asareas to bound link-state advertisement.An area is the portion of a network within which LSAsare connected.

82

OSPF (cont.)

All OSPF routers configured with the same areas identification will acceptLSAs from one another.Fig. 9-29 shows an OSPFnetwork that has been designed with two areas.

83

OSPF (cont.)

In Fig. 9-29, areas 0 LSAsaffect only routers A, B, andC. LSAs for area 1 only affect routers B, E, F, and D.Therefore, if a link on

RouterA goes down, it will inform RouterB and RouterCthat the link has gone down.

84

OSPF Concept

OSPF (cont.)

In OSPF, the adjacencies database contains information about all OSPF peer with which a router has successfully exchanged Hello packets.

85

OSPF (cont.)

OSPF Concept (cont.)Once two neighboring

routers establishbidirectional comm. via Hello packets, they add one another to their respective adjacency databases.

86

OSPF (cont.)

Hellos are multicast to a special multicast address of 224.0.0.5.

On multi-access networks such as Ethernet, Hellos are sent every 10 sec by default.

OSPF Concept (cont.)

87

OSPF (cont.)

On non-broadcast networks such as Frame Relay, Hellos are sent every 30 seconds by default.


88

OSPF (cont.)

OSPF also uses a topological database, which holds the common view of the network formed fromLSAs that are received.


89

OSPF (cont.)

OSPF Concept (cont.)The topological

database allows the routers to run Dijkstra’sSPF algorithm and find the best path to a network.

90

OSPF (cont.)

OSPF OperationOSPF goes through a series of steps to get a router up and running.

The first thing an OSPFrouter does is form adjacencies with neighbors.

91

OSPF (cont.)

OSPF Operation (cont.)

The second thing that occurs in OSPF is the election of a DR andBDR.

92

OSPF (cont.)

OSPF Operation (cont.)Finally, the routers will

flood their link-state advertisements and gothrough the process of selecting the best routeto each network.

93

OSPF (cont.)

OSPF Operation (cont.)Fig. 9-33 show the

example network that will be used for the rest of this chapter.

94

OSPF (cont.)

OSPF Operation (cont.)Fig. 9-34 displays the

show ip ospf neighborcommand output from RouterB. It clearly shows that RouterB has RouterAand RouterC in its adjacency database.

95

補充OSPF的運作原理OSPF的運作方式如下：建立路由器的相連

發現路徑

選擇路徑

維護路徑資訊

OSPF (cont.)

96

OSPF的運作原理(續)建立路由器的相連(Establishing Route Adjacencies)藉由Hello協定，建立兩個路由器間連結關係，

並可相互交換連結狀態

訊息。

OSPF (cont.)

97

Hello封包是以Multicast位址(224.0.0.5)方式，傳送到各個路由器。

建立路由器的相連(續)OSPF的運作原理(續)

OSPF (cont.)

98

新加入路由器R1時，R1尚未運作，此時R1開始送出Hello packet。


OSPF (cont.)

99

所有的routers (R2, R3, andR4)收到此Hello packet後，會先將R1納入Adjacencies Database ，再回應 Hello packet給R1。


OSPF (cont.)

100

R1收到相鄰routers的Hello packet後，會將這些資訊加入自己的 Adjacencies Database。


OSPF (cont.)

101

此時R1與R2、R1與R3及R1與R4都有雙方的資訊，於是建立了雙方的溝

通管道。


OSPF (cont.)

102

選擇 DR (Designated Router) 與 BDR (BackupDesignated Router)的主要目的是，降低路徑更改的流

量與維護連結狀態的同步。


OSPF (cont.)

103

若路由器 R2 擁有較高的priority值，則被選為DR；若路由器R4擁有次高的priority值，則被選為BDR。選完DR與BDR後，所有的路由器只能跟DR與BDR交換資訊。


OSPF (cont.)

104

當DR與BDR被選定後，新加入的路由器就只會跟DR與BDR交換資訊，而不會與其他的路由器交換資訊。


OSPF (cont.)

105

(註：BDR的主要用途，是當DR故障時，BDR會取而代之。)


OSPF (cont.)

106

Exstart stateExchange stateLoading stateFull state

發現路徑 (Discovering Route)

OSPF的運作原理(續)

OSPF (cont.)

107

Exstart state:在選定DR與BDR後，routers就進入Exstart state，然後向DR送出Hello封包。

發現路徑(續)OSPF的運作原理(續)

OSPF (cont.)

108

Exchange state: DR與其他routers開始進行交換連結狀態資訊。


OSPF (cont.)

109

Loading state: DR與其他routers在交換一次或多次的 DD (Database Description)封包的過程，雙方皆會回應 LSACK (Link-state ACK)。


OSPF (cont.)

110

Full state: 當所有的routers都有相同的連結狀態資料庫時，就處於

Full state。


OSPF (cont.)

111

選擇路徑(Choosing Route)當所有的routers都就處於Full state時，緊接著是建立路徑表。而選擇路徑就是從臨接路徑表中，選出最佳路徑。

OSPF的運作原理(續)

OSPF (cont.)

112

預設的連線成本計算方式

100,000,000 / 線路頻寬

選擇路徑(續)

OSPF (cont.)

113

OSPF (cont.)

Table 9-3 shows Cisco’s default OSPF costs for certain link types.

114

Cost = 220

選擇路徑(續)

OSPF (cont.)

115

OSPF計算最佳路徑範例

OSPF (cont.)

116

OSPF的運作原理(續)維護路徑資訊(Maintaining Routing Information)

Routers維護路徑資訊的步驟如下：

OSPF (cont.)

117

OSPF的運作原理(續)維護路徑資訊(續)

偵測到網路發生異動的

Router 會以 Multicast 224.0.0.6傳送LSU (Link State Update)封包給DR與BDR。

OSPF (cont.)

118


DR在收到LSU封包後，會利用 Multicast 224.0.0.5傳送給其他的routers。

OSPF (cont.)

119


一般的routers收到DR送來的LSU封包後，若其有連結到其他網路，則會再

轉送出去。

OSPF (cont.)

120


否則，這些routers會先更新自己的連結狀態資料庫

(Link State Database)，再建立新的路徑表。

OSPF (cont.)

121

OSPF (cont.)

Single-Area OSPF Configuration The commands to

configure single-areaOSPF on RouterB are displayed in Fig. 9-35.

122

OSPF (cont.)

Two major commands are needed for OSPF.The first is router ospf[process id], which turns on OSPF. The process id is similar to a process on a OS.

123

OSPF (cont.)

The other major command is the networkcommand.

124

OSPF (cont.)

OSPF uses wildcard masks in networkstatement. Once these two commands are entered, the router begin the process of formingadjacencies and developingtopological database.

125

Wildcard Mask的說明當Wildcard Mask的位元為0時，表示don’t care；當位元為1時，表示need match。若此值省略時，則為預設值0.0.0.0。

OSPF (cont.)

126

範例一：

Source: 203.66.47.1Source-Wildcard : 0.0.0.255屬於203.66.47.0網段的位址，都符合。

Wildcard Mask的說明(續)

OSPF (cont.)

127

範例二：

Source: 203.66.47.50Source-Wildcard : 0.0.0.0只有203.66.47.50的IP位址符合。


OSPF (cont.)

128


OSPF (cont.)

129

Which of the followingwildcard mask will you use to match the range180.80.32.0~180.80.63.255?

Ans: CE. 0.0.255.255

A. 0.0.0.0B. 255.255.255.255D. 0.0.0.255

OSPF (cont.)

130

Which IP address and wildcard mask would you see in the subnet 202.168.16.43/28?

Ans: A

A. 202.168.16.32 0.0.0.15B. 202.168.16.32 0.0.0.16C. 202.168.16.32 0.0.0.7D. 202.168.16.32 0.0.0.8

OSPF (cont.)

131

Interior IP Routing Protocols Compared

132


Contents

OSPF


133

Controlling Route Traffic

The passive-interfacecommand is an important entry-level command for controlling route traffic.

134

Controlling Route Traffic (cont.)

In Fig. 9-37, RouterD may need to learn of the RIProutes on the rest of the network, but the network does not need to know its routes because RouterB is configured to route itstatically.

135

In short, you need a way for RouterD to hear RIPupdates, but not sent outupdates. The passive-interface commandallows this.


136

Unfortunately, this command disrupts the functions of EIGRP and OSPF. The commandcauses a router to listen only on the passive interface.


137


Contents

OSPF


138

◆ Which three of following tables will OSPF router maintain?

Ans: a, c, d

a. Routing tableb. Hello tablec. Topological databased. Adjacencies databasee. Distance-vector table

Review Questions

139

◆ How does OSPF compute the distance of cost?

Ans: b

a. 106/bandwidthb. 108/bandwidthc. bandwidth/108

d. bandwidth/106

e. None of the above

Review Questions (cont.)

140

◆ Which one of the followingmulticast addresses will router use to inform DR when the network topology changed?

Ans: b

a. 224.0.0.5b. 224.0.0.6c. 224.0.0.9d. 224.0.0.10e. None of the above


141

◆ Which one of the followingmulticast address will DRreceive change and flood the LSU to other routers on the OSPF network?

Ans: a

a. 224.0.0.5b. 224.0.0.6c. 224.0.0.9d. 224.0.0.10


142

◆ Which three of following routing protocols support route summarization?

Ans: c, d, e

a. RIPb. IGRPc. OSPFd. EIGRPe. RIP-2


143

◆ Which of the following protocols is considered to use link-state logic?

Ans: c

a. RIPb. IGRPc. OSPFd. EIGRPe. None of the above


144

◆ Which of the following interior protocols support VLSM?

Ans: c, d

a. RIPb. IGRPc. OSPFd. EIGRP


145

Q12: Which of the following protocols are considered to be capable of converging quickly?

Ans: c, d

a. RIPb. IGRPc. OSPFd. EIGRP


146

◆ What is the maximum entries number in the routing table for the same destination of EIGRP network?

Ans: c

a. 2b. 4c. 6d. 8e. None of the above


147

◆ What is the default entriesnumber in the routing table for the same destination of EIGRP network?

Ans: b

a. 2b. 4c. 6d. 8e. None of the above


148

◆ Which one of the following multicast addresses is used by EIGRP?

Ans: d

a. 224.0.0.5b. 224.0.0.6c. 224.0.0.9d. 224.0.0.10e. None of the above


149

◆ Which one of following routing protocols will you used to support multiple routed protocols?

Ans: d

a. RIPb. IGRPc. OSPFd. EIGRPe. None of the above


150

◆ Classless routing protocols carry _________ in their routing table?

Ans: subnet mask information


151

◆ A backup route in EIGRPis a(n) _________.

Ans: Feasible Successor


152

◆ What command switchesRIP to version 2?

Ans: b

a. router rip 2b. version 2c. rip version 2d. ripv2 one. None of the above


153

◆ Which type of authenticationsend only a hash across a link between two authentication peers?

Ans: a

a. MD5b. Clear textc. Signed secret keysd. Shared keyse. None of the above


154

◆ What command places the192.168.12.32/27 network into OSPF area 0?

Ans: d

a. network 192.168.12.0 area 0b. network 192.168.12.32 area 0c. network 192.168.12.0

255.255.255.224 area 0d. network 192.168.12.32

0.0.0.31 area 0


155

◆ What protocol is used byEIGRP to transport its routing protocol information?

Ans: c

a. TCPb. UDPc. RTPd. SPXe. None of the above


156

◆ What algorithm is used byOSPF for path selection?

Ans: c

a. DUALb. Open Path Firstc. Shortest Path Firstd. Default-Information Originatee. None of the above


157

◆ What command displays the successors and feasible successor for EIGRP?

Ans: b

a. show ip routeb. show ip eigrp topologyc. show runningd. show ip topologye. None of the above


158

Which interior IP routing protocols support VLSM?

Ans: RIP-2, EIGRP, OSPF, and Integrated IS-IS.

Short Question

159

Which IP routing protocols use distance-vector logic?Ans: RIPv1, RIPv2, and IGRP.

Short Question

160

Which interior IP routing protocols are considered to converge quickly?

Ans: EIGRP, OSPF, andIntegrated IS-IS.

Short Question

161

List three similarities between EIGRP’s balanced hybrid logicand link-state logic.

Ans: Fast convergence

Short Question

not sending full updateson a particular period

neighbor discovery before sending routing info

162

Explain the differencesbetween full and partial routing updates.

Short Question

163

Ans: Full routing updatesinclude information about each subnet during each update period. Partial updates just include change routes, such as newly learned subnets and subnets whose routes have failed.

Short Question (cont.)

164

Define the term balanced hybrid in relation to the terms distance vector and link state.

Short Question

165

Ans: Balanced hybrid is a term used refer to the logic used by EIGRP. The logiccan be viewed as a combination of features like those of distance vectorand link state protocols.


166

What is the smallest summarized route that summarizes the subnets 10.1.63.0, 10.1.64.0, 10.1.70.0, and 10.1.71.0, all with mask 255.255.255.0?

Short Question

167

Ans: Only the first 17 bits of these subnets are in common. Therefore, the smallest summary is 10.1.0.0, all with mask 255.255.128.0.


168

What is the smallest summarized route that summarizes the subnets 10.5.111.0, 10.5.112.0, 10.5.113.0, and 10.5.114.0, all with mask 255.255.255.0?

Short Question

169

Ans: The first 19 bits of these subnets are in common. Therefore, the smallestsummary is 10.5.96.0, all with mask 255.255.224.0.


170

What is the smallest summarized route that summarizes the subnets 10.5.110.32, 10.5.110.48, and 10.5.110.64, all with mask255.255.255.248?

Short Question

171

Ans: The first 25 bits of these subnets are in common. Therefore, the smallestsummary is 10.5.110.0, all with mask 255.255.255.128.


172

Of the routing protocolsRIPv1, RIPv2, IGRP, EIGRP, and OSPF, which are classless ?Ans: RIPv2, EIGRP and

OSPF.

Short Question

173

Of the routing protocolsRIPv1, RIPv2, IGRP, EIGRP, and OSPF, which support VLSM ?Ans: RIPv2, EIGRP and

OSPF.

Short Question

Chapter 9210.70.254.122/chingyu/Ch9 Advanced Routing Protocols.pdf · 2007. 9. 26. · EIGRP (cont.) Fig. 9-22 shows the output of the‘show ip eigrp neighbors’ command on RouterA

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