flokinet-009 - routing recap

title: flokinet-009 - routing recap
author: Nicholas Morrison
draft: false
tags: [network, workshop, arista]
categories: [workshop]
noindex: true

Routing

A router making a choice
A router making a choice

Static Routes

“For packets with destinations in this network, send them to this router.”

!
ip route   192.168.100.0/24      10.10.10.5
!                ^ destination        ^ router

Binary logic briefing

More binary logic examples

ANDing for Quantisation with 8 bits

More ANDing for fun and quantisation

ANDing and IPv4

HOWTO select a route

A packet arrives for forwarding with destination 192.168.100.1. Which route will be chosen?

r7#show ip route
...
Gateway of last resort is not set

 C        10.0.0.0/24 is directly connected, Ethernet1
 S        192.168.100.0/32 [1/0] via 10.0.0.5, Ethernet1
 S        192.168.100.0/30 [1/0] via 10.0.0.4, Ethernet1
 S        192.168.100.0/27 [1/0] via 10.0.0.3, Ethernet1
 S        192.168.100.0/24 [1/0] via 10.0.0.2, Ethernet1

r7#

Most-specific match example: /32

Most-specific match example: /30

Most-specific match example: /27

Most-specific match example: /24

24 bits of netmask (255.255.255.0):

The route is chosen.

HOWTO select a route: 192.168.100.25

A packet arrives for forwarding with destination 192.168.100.25. Which route will be chosen?

r7#show ip route
...
Gateway of last resort is not set

 C        10.0.0.0/24 is directly connected, Ethernet1
 S        192.168.100.0/32 [1/0] via 10.0.0.5, Ethernet1
 S        192.168.100.0/30 [1/0] via 10.0.0.4, Ethernet1
 S        192.168.100.0/27 [1/0] via 10.0.0.3, Ethernet1
 S        192.168.100.0/24 [1/0] via 10.0.0.2, Ethernet1

r7#

Static route 192.168.100.0/32

Static route 192.168.100.0/30

Static route 192.168.100.0/27

Static route 192.168.100.0/24

24 bits of netmask (255.255.255.0):

The route is chosen.

Summary

Questions!