因为可靠性和负载是动态的度量，这种算法不允许链路上有突然的大的流量变化和出错率，这样会造成整个网络结构的不稳定，如流量的突然降低可能会导致路由器触发一个更新，为了防止度量的频繁改变，采用5秒种更新一次的方式。
大流量通过路由器的接口将会导致路由器的负载加大，如下所示，当CPU的利用上升超过70%以上的时候不同种类的路由器会相续选择丢包处理，当一直处了90%或者更高的时候，路由器将无法正常转发或导致死机。
R2#show int s 1
Serial1 is up, line protocol is up
Hardware is HD64570
Internet address is 10.10.10.2/24
MTU 1500 bytes, BW 64 Kbit, DLY 1000 usec,
reliability 255/255, txload 63/255, rxload 59/255 ←有流量通过时，负载增大。
Encapsulation HDLC, loopback not set
Keepalive set (10 sec)
Last input 00:00:03, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Input queue: 1/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/1/256 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
Available Bandwidth 48 kilobits/sec
5 minute input rate 15000 bits/sec, 2 packets/sec
5 minute output rate 16000 bits/sec, 2 packets/sec
4678 packets input, 494690 bytes, 0 no buffer
Received 1555 broadcasts, 0 runts, 0 giants, 0 throttles
1 input errors, 1 CRC, 0 frame, 0 overrun, 0 ignored, 1 abort
4670 packets output, 494456 bytes, 0 underruns
0 output errors, 0 collisions, 2 interface resets
0 output buffer failures, 0 output buffers swapped out
8 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=up
R2#
因链路错误和波动导致可靠性下降，如下所示。
R2#show int s 1
Serial1 is up, line protocol is up
Hardware is HD64570
Internet address is 10.10.10.2/24
MTU 1500 bytes, BW 64 Kbit, DLY 1000 usec,
reliability 254/255, txload 15/255, rxload 19/255 ←链路可靠性下降
Encapsulation HDLC, loopback not set
Keepalive set (10 sec)
Last input 00:00:02, output 00:00:02, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/1/256 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
Available Bandwidth 48 kilobits/sec
5 minute input rate 5000 bits/sec, 0 packets/sec
5 minute output rate 4000 bits/sec, 0 packets/sec
6265 packets input, 1847204 bytes, 0 no buffer
Received 1653 broadcasts, 0 runts, 0 giants, 0 throttles
5 input errors, 5 CRC, 0 frame, 0 overrun, 0 ignored, 5 abort
6251 packets output, 1845964 bytes, 0 underruns
0 output errors, 0 collisions, 3 interface resets
0 output buffer failures, 0 output buffers swapped out
15 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=up
R2#
在默认情况下IGRP和EIGRP采用带宽和延迟进行度量运算，我们可以用以下的命令来开启其他度量值。
在缺省情况下K1=K3=1 K2=K4=K5=0，K1和K3分别表示带宽和延迟。
其具体的计算公式和步骤请查阅IT傻博士学习手册，以下所列为权重各K值。
R1(config-router)#metric weights ? ←配置选用的参考值
<0-8> Type Of Service (Only TOS 0 supported)
R1(config-router)#metric weights 0 ?
<0-255> K1
R1(config-router)#metric weights 0 1 ?
<0-255> K2
R1(config-router)#metric weights 0 1 0 ?
<0-255> K3
R1(config-router)#metric weights 0 1 0 5 ?
<0-255> K4
R1(config-router)#metric weights 0 1 0 5 1 ?
<0-255> K5
R1(config-router)#metric weights 0 1 0 5 1 0
如果我们想查看运行EIGRP协议的邻居路由器可以通过show ip eigrp neighbors来实现，显示如下。
R1#show ip eigrp neighbors
IP-EIGRP neighbors for process 1
H Address Interface Hold Uptime SRTT RTO Q Seq
(sec) (ms) Cnt Num
0 10.10.10.2 Se1 10 00:19:12 32 200 0 48
R1#
若查看EIGRP的拓扑表可通过show ip eigrp topology来实现，其显示如下。
R1#show ip eigrp topo
IP-EIGRP Topology Table for AS(1)/ID(0.0.0.0)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - reply Status, s - sia Status
P 10.10.10.0/24, 1 successors, FD is 1709056
via Connected, Serial1
P 20.0.0.0/8, 1 successors, FD is 2221056
via 10.10.10.2 (2221056/2169856), Serial1
R1#
以上加粗的内容逐一解释如下。
P 20.0.0.0/8, 1 successors, FD is 2221056
via 10.10.10.2 (2221056/2169856), Serial1
P 20.0.0.0/8：目的网络的网络号和掩码长度。
1 successors, FD is 2221056：表示有一个后继路由器，并且从源点到达目的地的开销为2169856
via 10.10.10.2：标识出经过下一跳路由器的接口地址。
(2221056/2169856)：前一个值2221056表示从源路由器到达目的地的开销值，后一个值2169856为下一跳路由器到达目的地的开销值。
Serial1：为本地出站接口。
在拓扑表中到达目的地最优的路径将成为后继，并被放入路由表中，现在我们查看一下路由表。
R1#show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route
Gateway of last resort is not set
D 20.0.0.0/8 [90/2221056] via 10.10.10.2, 00:43:22, Serial1
10.0.0.0/24 is subnetted, 1 subnets
C 10.10.10.0 is directly connected, Serial1
R1#
从中可以看出最优路径已经被放入路由表中。
