[笔记] Eigrp.04Metric计算.md

EIGRP Metric（度量值）

Eigrp_topology.png

• 跟IGRP一样使用一下五个参数来计算度量值:

• Bandwidth 带宽

  沿途最小带宽

• Delay 延时

  时延总和

• Reliability 可靠性

• Loading 负载

• MTU 最大传输单元

• EIGRP的度量值是IGRP的256倍

• 这是eigrp的评选三好生的五要素“德智体美劳”，但总有些决定因素,比如智力

EIGRP 度量值的计算方法

• 默认情况下， K1=K3=1,K2=K4=K5=0，公式等于Metric = 256 * [bandwidth + delay]

• bandwidth = 10^7 / BW(min，最小带宽)

• delay = delay(sum，延时总和) / 10

• Metric = 256×(10^7/BWmin + Delaysum/10)

验证：R1->44.1.1.0

Metric=256*[10000000/1544+(20000+1000+5000)/10]
=256[6476(去整，向小取)+2600]
=2323456

R1#show ip route 44.1.1.1 255.255.255.0
Routing entry for 44.1.1.0/24
  Known via "eigrp 90", distance 90, metric 2323456, type internal
  Redistributing via eigrp 90
  Last update from 13.1.1.3 on Serial1/1, 01:30:31 ago
  Routing Descriptor Blocks:
  * 13.1.1.3, from 13.1.1.3, 01:30:31 ago, via Serial1/1
      Route metric is 2323456, traffic share count is 1
      Total delay is 26000 microseconds, minimum bandwidth is 1544 Kbit
      Reliability 255/255, minimum MTU 1500 bytes
      Loading 1/255, Hops 2

最小带宽

R1#show interfaces s1/1
Serial1/1 is up, line protocol is up 
  Hardware is M4T
  Internet address is 13.1.1.1/24
  MTU 1500 bytes, BW 1544 Kbit/sec, DLY 20000 usec, 
     reliability 255/255, txload 1/255, rxload 1/255

延时=s1/0+eth0/0+lo0

R1#show interfaces s1/1
Serial1/1 is up, line protocol is up 
  Hardware is M4T
  Internet address is 13.1.1.1/24
  MTU 1500 bytes, BW 1544 Kbit/sec, DLY 20000 usec, 
     reliability 255/255, txload 1/255, rxload 1/255

R3#sh interfaces ethernet 0/0
Ethernet0/0 is up, line protocol is up 
  Hardware is AmdP2, address is aabb.cc00.0300 (bia aabb.cc00.0300)
  Internet address is 34.1.1.3/24
  MTU 1500 bytes, BW 10000 Kbit/sec, DLY 1000 usec, 
     reliability 255/255, txload 1/255, rxload 1/255

R4#sh interfaces loopback 0
Loopback0 is up, line protocol is up 
  Hardware is Loopback
  Internet address is 44.1.1.1/24
  MTU 1514 bytes, BW 8000000 Kbit/sec, DLY 5000 usec, 
     reliability 255/255, txload 1/255, rxload 1/255