实验目的
实验拓扑
实验需求
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根据实验拓扑图,完成设备的基本配置;
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在R1、R2、R3上启用EIGRP 100,关闭自动汇总并宣告相应的接口;
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通过配置R2,使得R2去往R3的环回口实现不等价负载均衡。
实验步骤
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设备基本配置
R1的基本配置如下:hostname R1 interface serial0/1/0 clock rate 64000 ip address 12.1.1.1 255.255.255.0 no shutdown interface serial0/1/1 clock rate 64000 ip address 13.1.1.1 255.255.255.0 no shutdown interface loopback1 ip address 10.1.1.1 255.255.255.0 interface loopback2 ip address 10.1.2.1 255.255.255.0 interface loopback3 ip address 10.1.3.1 255.255.255.0
R2的基本配置如下:hostname R2 interface serial0/0 ip address 12.1.1.2 255.255.255.0 no shutdown interface serial0/1 clock rate 64000 ip address 23.1.1.2 255.255.255.0 no shut interface loopback1 ip address 20.1.1.1 255.255.255.0 interface loopback2 ip address 20.1.2.1 255.255.255.0 interface loopback3 ip address 20.1.3.1 255.255.255.0
R3的基本配置如下:hostname R3 interface serial0/0 ip address 13.1.1.3 255.255.255.0 no shutdown interface serial0/1 ip address 23.1.1.3 255.255.255.0 no shut interface loopback1 ip address 30.1.1.1 255.255.255.0 interface loopback2 ip address 30.1.2.1 255.255.255.0 interface loopback3 ip address 30.1.3.1 255.255.255.0
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在R1、R2、R3上配置EIGRP 100
R1的EIGRP配置如下:router eigrp 100 no auto-summary network 12.1.1.0 0.0.0.255 network 13.1.1.0 0.0.0.255 network 10.1.1.0 0.0.0.255 network 10.1.2.0 0.0.0.255 network 10.1.3.0 0.0.0.255
R2的EIGRP配置如下:router eigrp 100 no auto-summary network 12.1.1.0 0.0.0.255 network 23.1.1.0 0.0.0.255 network 20.1.1.0 0.0.0.255 network 20.1.2.0 0.0.0.255 network 20.1.3.0 0.0.0.255
R3的EIGRP配置如下:router eigrp 100 no auto-summary network 13.1.1.0 0.0.0.255 network 23.1.1.0 0.0.0.255 network 30.1.1.0 0.0.0.255 network 30.1.2.0 0.0.0.255 network 30.1.3.0 0.0.0.255
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在R1、R2、R3上检查EIGRP路由
R1的EIGRP路由如下:R1#show ip route eigrp 20.0.0.0/24 is subnetted, 3 subnets D 20.1.1.0 [90/2297856] via 12.1.1.2, 00:01:16, Serial0/1/0 D 20.1.3.0 [90/2297856] via 12.1.1.2, 00:01:16, Serial0/1/0 D 20.1.2.0 [90/2297856] via 12.1.1.2, 00:01:16, Serial0/1/0 23.0.0.0/24 is subnetted, 1 subnets D 23.1.1.0 [90/2681856] via 13.1.1.3, 00:01:16, Serial0/1/1 [90/2681856] via 12.1.1.2, 00:01:16, Serial0/1/0 30.0.0.0/24 is subnetted, 3 subnets D 30.1.3.0 [90/2297856] via 13.1.1.3, 00:01:16, Serial0/1/1 D 30.1.2.0 [90/2297856] via 13.1.1.3, 00:01:16, Serial0/1/1 D 30.1.1.0 [90/2297856] via 13.1.1.3, 00:01:16, Serial0/1/1
R1去往23.1.1.0/24存在两条路径,一条通过R2到达另外一条通过R3到达,但是不管通过R2到达还是通过R3到达,沿途路径的Metric是相等的,又因为都是通过EIGRP学习到的路由,AD值都是90,所以R1路由表里面去往23.1.1.0/24是等价负载的路径。
R2的EIGRP路由如下:
R2#show ip route eigrp 10.0.0.0/24 is subnetted, 3 subnets D 10.1.3.0 [90/2297856] via 12.1.1.1, 00:01:56, Serial0/0 D 10.1.2.0 [90/2297856] via 12.1.1.1, 00:01:56, Serial0/0 D 10.1.1.0 [90/2297856] via 12.1.1.1, 00:01:56, Serial0/0 13.0.0.0/24 is subnetted, 1 subnets D 13.1.1.0 [90/2681856] via 23.1.1.3, 00:01:56, Serial0/1 [90/2681856] via 12.1.1.1, 00:01:56, Serial0/0 30.0.0.0/24 is subnetted, 3 subnets D 30.1.3.0 [90/2297856] via 23.1.1.3, 00:01:56, Serial0/1 D 30.1.2.0 [90/2297856] via 23.1.1.3, 00:01:56, Serial0/1 D 30.1.1.0 [90/2297856] via 23.1.1.3, 00:01:56, Serial0/1
R3的EIGRP路由如下:R3#show ip route eigrp 20.0.0.0/24 is subnetted, 3 subnets D 20.1.1.0 [90/2297856] via 23.1.1.2, 00:00:02, Serial0/1 D 20.1.3.0 [90/2297856] via 23.1.1.2, 00:00:02, Serial0/1 D 20.1.2.0 [90/2297856] via 23.1.1.2, 00:00:02, Serial0/1 10.0.0.0/24 is subnetted, 3 subnets D 10.1.3.0 [90/2297856] via 13.1.1.1, 00:00:02, Serial0/0 D 10.1.2.0 [90/2297856] via 13.1.1.1, 00:00:02, Serial0/0 D 10.1.1.0 [90/2297856] via 13.1.1.1, 00:00:02, Serial0/0 12.0.0.0/24 is subnetted, 1 subnets D 12.1.1.0 [90/2681856] via 23.1.1.2, 00:00:02, Serial0/1 [90/2681856] via 13.1.1.1, 00:00:02, Serial0/0
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EIGRP不等价负载均衡的实现
首先我们来看R2的EIGRP拓扑表:R2#show ip eigrp topology IP-EIGRP Topology Table for AS(100)/ID(20.1.3.1) Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply, r - reply Status, s - sia Status P 10.1.3.0/24, 1 successors, FD is 2297856 via 12.1.1.1 (2297856/128256), Serial0/0 P 10.1.2.0/24, 1 successors, FD is 2297856 via 12.1.1.1 (2297856/128256), Serial0/0 P 10.1.1.0/24, 1 successors, FD is 2297856 via 12.1.1.1 (2297856/128256), Serial0/0 P 12.1.1.0/24, 1 successors, FD is 2169856 via Connected, Serial0/0 P 13.1.1.0/24, 2 successors, FD is 2681856 via 12.1.1.1 (2681856/2169856), Serial0/0 via 23.1.1.3 (2681856/2169856), Serial0/1 P 20.1.1.0/24, 1 successors, FD is 128256 via Connected, Loopback1 P 20.1.3.0/24, 1 successors, FD is 128256 via Connected, Loopback3 P 20.1.2.0/24, 1 successors, FD is 128256 via Connected, Loopback2 P 23.1.1.0/24, 1 successors, FD is 2169856 Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply, r - reply Status, s - sia Status via Connected, Serial0/1 P 30.1.3.0/24, 1 successors, FD is 2297856 via 23.1.1.3 (2297856/128256), Serial0/1 P 30.1.2.0/24, 1 successors, FD is 2297856 via 23.1.1.3 (2297856/128256), Serial0/1 P 30.1.1.0/24, 1 successors, FD is 2297856 via 23.1.1.3 (2297856/128256), Serial0/1
发现R2去往R3的三个环回口下一跳都为23.1.1.3,存在Successor R3,FD为2297856,AD为128256。事实上R2去往这三个网段是存在两条路径的,一条路径通过R1到达,另外一条路径通过R3到达,但是为什么R1没有成为Feasible Successor呢?
我们来看R2详细的拓扑表:
R2#show ip eigrp topology all-links IP-EIGRP Topology Table for AS(100)/ID(20.1.3.1) Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply, r - reply Status, s - sia Status P 10.1.3.0/24, 1 successors, FD is 2297856, serno 148 via 12.1.1.1 (2297856/128256), Serial0/0 via 23.1.1.3 (2809856/2297856), Serial0/1 P 10.1.2.0/24, 1 successors, FD is 2297856, serno 147 via 12.1.1.1 (2297856/128256), Serial0/0 via 23.1.1.3 (2809856/2297856), Serial0/1 P 10.1.1.0/24, 1 successors, FD is 2297856, serno 146 via 12.1.1.1 (2297856/128256), Serial0/0 via 23.1.1.3 (2809856/2297856), Serial0/1 P 12.1.1.0/24, 1 successors, FD is 2169856, serno 35 via Connected, Serial0/0 P 13.1.1.0/24, 2 successors, FD is 2681856, serno 149 via 12.1.1.1 (2681856/2169856), Serial0/0 via 23.1.1.3 (2681856/2169856), Serial0/1 P 20.1.1.0/24, 1 successors, FD is 128256, serno 7 via Connected, Loopback1 P 20.1.3.0/24, 1 successors, FD is 128256, serno 9 via Connected, Loopback3 Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply, r - reply Status, s - sia Status P 20.1.2.0/24, 1 successors, FD is 128256, serno 8 via Connected, Loopback2 P 23.1.1.0/24, 1 successors, FD is 2169856, serno 131 via Connected, Serial0/1 P 30.1.3.0/24, 1 successors, FD is 2297856, serno 142 via 23.1.1.3 (2297856/128256), Serial0/1 via 12.1.1.1 (2809856/2297856), Serial0/0 P 30.1.2.0/24, 1 successors, FD is 2297856, serno 141 via 23.1.1.3 (2297856/128256), Serial0/1 via 12.1.1.1 (2809856/2297856), Serial0/0 P 30.1.1.0/24, 1 successors, FD is 2297856, serno 140 via 23.1.1.3 (2297856/128256), Serial0/1 via 12.1.1.1 (2809856/2297856), Serial0/0
我们发现,如果R2通过R1去往R3的三个环回口,AD为2297856,FD为2809856,然而要成为Feasible Successor必须满足可行条件(FC):
AD of Second Best Route < FD of Best Route(后备路径的AD < 当前的FD),现在通过R1前往的AD为2297856,和当前的FD=2297856相等,没有满足FC,所以R1不能成为Feasible Successor。
R2上作如下修改:
interface Serial0/1 bandwidth 128 clear ip eigrp neighbor
检查R2的EIGRP拓扑表:R2#show ip eigrp topology IP-EIGRP Topology Table for AS(100)/ID(20.1.3.1) Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply, r - reply Status, s - sia Status P 10.1.3.0/24, 1 successors, FD is 2297856 via 12.1.1.1 (2297856/128256), Serial0/0 P 10.1.2.0/24, 1 successors, FD is 2297856 via 12.1.1.1 (2297856/128256), Serial0/0 P 10.1.1.0/24, 1 successors, FD is 2297856 via 12.1.1.1 (2297856/128256), Serial0/0 P 12.1.1.0/24, 1 successors, FD is 2169856 via Connected, Serial0/0 P 13.1.1.0/24, 1 successors, FD is 2681856 via 12.1.1.1 (2681856/2169856), Serial0/0 via 23.1.1.3 (21024000/2169856), Serial0/1 P 20.1.1.0/24, 1 successors, FD is 128256 via Connected, Loopback1 P 20.1.3.0/24, 1 successors, FD is 128256 via Connected, Loopback3 P 20.1.2.0/24, 1 successors, FD is 128256 via Connected, Loopback2 P 23.1.1.0/24, 1 successors, FD is 20512000 Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply, r - reply Status, s - sia Status via Connected, Serial0/1 via 12.1.1.1 (3193856/2681856), Serial0/0 P 30.1.3.0/24, 1 successors, FD is 2809856 via 12.1.1.1 (2809856/2297856), Serial0/0 via 23.1.1.3 (20640000/128256), Serial0/1 P 30.1.2.0/24, 1 successors, FD is 2809856 via 12.1.1.1 (2809856/2297856), Serial0/0 via 23.1.1.3 (20640000/128256), Serial0/1 P 30.1.1.0/24, 1 successors, FD is 2809856 via 12.1.1.1 (2809856/2297856), Serial0/0 via 23.1.1.3 (20640000/128256), Serial0/1
通过调整R2 Serial0/1接口的bandwidth之后,我们发现现在R2去往R3的三个环回口网段,Successor为R1,Feasible Successor为R3,因为通过R3前往满足可行条件(FC):128256 < 2809869。那是不是存在Feasible Successor的情况下EIGRP就能自动实现不等价负载均衡了呢?不会!
我们来观察R2的路由表:
R2#show ip route eigrp 10.0.0.0/24 is subnetted, 3 subnets D 10.1.3.0 [90/2297856] via 12.1.1.1, 00:00:13, Serial0/0 D 10.1.2.0 [90/2297856] via 12.1.1.1, 00:00:13, Serial0/0 D 10.1.1.0 [90/2297856] via 12.1.1.1, 00:00:13, Serial0/0 13.0.0.0/24 is subnetted, 1 subnets D 13.1.1.0 [90/2681856] via 12.1.1.1, 00:00:13, Serial0/0 30.0.0.0/24 is subnetted, 3 subnets D 30.1.3.0 [90/2809856] via 12.1.1.1, 00:00:13, Serial0/0 D 30.1.2.0 [90/2809856] via 12.1.1.1, 00:00:13, Serial0/0 D 30.1.1.0 [90/2809856] via 12.1.1.1, 00:00:13, Serial0/0
发现R2并没有负载。
那存在Feasible Successor的情况下,EIGRP如何实现不等价负载均衡呢?我们要借助于variance参数,并且必须满足如下条件:
FS's FD < U*Successor's FD
当前Successor的FD为2809856,Feasible Successor的FD为20640000,要满足以上公式U至少取8才行。
对R2进行如下配置:
router eigrp 100 variance 8
检查R2的路由表R2#show ip route eigrp 10.0.0.0/24 is subnetted, 3 subnets D 10.1.3.0 [90/2297856] via 12.1.1.1, 00:00:04, Serial0/0 D 10.1.2.0 [90/2297856] via 12.1.1.1, 00:00:04, Serial0/0 D 10.1.1.0 [90/2297856] via 12.1.1.1, 00:00:04, Serial0/0 13.0.0.0/24 is subnetted, 1 subnets D 13.1.1.0 [90/21024000] via 23.1.1.3, 00:00:04, Serial0/1 [90/2681856] via 12.1.1.1, 00:00:04, Serial0/0 30.0.0.0/24 is subnetted, 3 subnets D 30.1.3.0 [90/20640000] via 23.1.1.3, 00:00:04, Serial0/1 [90/2809856] via 12.1.1.1, 00:00:04, Serial0/0 D 30.1.2.0 [90/20640000] via 23.1.1.3, 00:00:04, Serial0/1 [90/2809856] via 12.1.1.1, 00:00:04, Serial0/0 D 30.1.1.0 [90/20640000] via 23.1.1.3, 00:00:04, Serial0/1 [90/2809856] via 12.1.1.1, 00:00:04, Serial0/0
发现,R2去往R3的环回口是负载均衡的,虽然AD一样,但是Metric值不一样,不等价负载均衡。