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Unix network interface configuration Cisco network interface configuration Static routes Default route Testing. Static Routing Exercise. Routing. Routing is done based on destination IP address Without routing, interface can only reach destinations via ARP

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Static routing exercise

Unix network interface configuration

Cisco network interface configuration

Static routes

Default route

Testing

Static Routing Exercise


Routing
Routing

  • Routing is done based on destination IP address

  • Without routing, interface can only reach destinations via ARP

  • Cannot reach a destination on another separate network without going through an intermediate device

  • A device with at least 2 interfaces can route


Routing1
Routing

  • Static routes

    • specifically instructs router on which route to take to a particular destination network

  • dynamic routes

    • learnt via routing protocols implemented on routers

  • default routes

    • route that instructs a machine where to send packets for destinations that are not on the routing table


Static routing
Static Routing

  • Advantages

    • Simple to configure and maintain

    • Secure as only defined routes can be accessed

    • Bandwidth is not used for sending routing updates

  • Disadvantages

    • Manual update of routes after changes

    • Explicit addition of routes for all networks


Ip routing configuration static default route example
IP Routing ConfigurationStatic/default route example

To Internet

172.16.3.2

172.16.1.0

255.255.255.0

172.16.2.2

172.16.3.1

172.16.2.1

ip route 172.16.1.0 255.255.255.0 172.16.2.1 - STATIC

ip route 0.0.0.0 0.0.0.0 172.16.3.1 - DEFAULT


SWITCH

HUB

HUB

HUB

HUB

HUB

HUB

HUB

HUB

HUB

HUB

A

B

PC

Router

PC

Router

C

D

PC

PC

Router

Router

E

F

PC

Router

PC

Router

G

H

PC

PC

Router

Router

I

J

PC

Router

PC

Router

Classroom Layout


Address allocation

A

B

81.199.108.80/28

81.199.108.96/28

C

D

81.199.108.112/28

81.199.108.128/28

E

F

81.199.108.160/28

81.199.108.144/28

G

H

81.199.108.176/28

81.199.108.192/28

I

J

81.199.108.208/28

81.199.108.224/28

Address Allocation

SWITCH

.1

.2

.3

.4

.5

.6

81.199.108.0/28

.7

.8

.9

.10


Address allocation1

You already have an IP address for your router’s backbone link (A=.1, B=.2, …)

You have a /28 for your local network (PC and router connected to hub)

Allocate your own host addresses from your local /28 network

Address Allocation


Network interface configuration freebsd

configure interface on Unix host link (A=.1, B=.2, …)

ifconfig fxp0 inetn.n.n.nnetmaskm.m.m.m

fxp0 is interface name

n.n.n.n is IP address

m.m.m.m is netmask

Network interface configuration - FreeBSD


Connect pc to router console

Connect cable to console port on router, serial port on FreeBSD box

Use the tip command to connect your keyboard and screen to the serial port

e.g. bash$ tip cuaa0c

You may have to edit /etc/remote

See man pages for tip(1) and remote(5)

Connect PC to router console


Network interface configuration cisco
Network interface configuration - Cisco FreeBSD box

  • configure backbone interface on cisco router

    conf t

    interface ethernet0/0

    ip address n.n.n.n m.m.m.m

    • ethernet0/0 is interface name

    • n.n.n.n is IP address

    • m.m.m.m is netmask

  • configure local interface on cisco router

    • ethernet0/1


Network interface configuration cisco1
Network interface configuration - Cisco FreeBSD box

  • Cisco global config should always include:

    ip classless

    ip subnet-zero

    no ip domain-lookup

  • Cisco interface config should usually include:

    no shutdown

    no ip proxy-arp

    no ip redirects


Test connectivity

PC can ping local interface of router FreeBSD box

Router can ping PC

PC cannot ping backbone interface of router

Router can ping other routers

PC cannot ping other routers or other PCs

Test connectivity


Add default route
Add default route FreeBSD box

  • Add route on PC

    route add default g.g.g.g

    • g.g.g.g is IP address of gateway (which is on cisco router)

  • Display forwarding table

    netstat -f inet -rn


Test connectivity1
Test connectivity FreeBSD box

  • All PCs can now reach backbone IP address of own row

  • Still can’t reach other rows

    • why?

    • Do a traceroute to troubleshoot


Add static routes to other rows
Add static routes to other rows FreeBSD box

  • On router, add static routes to other rows

    • next hop is backbone interface of other row’s router

      ip routen.n.n.n m.m.m.m g.g.g.g

  • Repeat many times


Test connectivity2
Test connectivity FreeBSD box

  • All routers can reach all PCs

  • All PCs can reach all backbone IP addresses

  • All PCs can reach PCs in other rows

  • Test with traceroute


Address allocation2

A FreeBSD box

B

81.199.108.80/28

81.199.108.96/28

C

D

81.199.108.112/28

81.199.108.128/28

E

F

81.199.108.160/28

81.199.108.144/28

G

H

81.199.108.176/28

81.199.108.192/28

I

J

81.199.108.208/28

81.199.108.224/28

Address Allocation

T2 router

SWITCH

81.199.108.14/28

.1

.2

.3

.4

.5

.6

81.199.108.0/28

.7

.8

.9

.10


Add static routes to classroom router
Add static routes to classroom router FreeBSD box

  • On router, remove all static routes

    no ip routen.n.n.n m.m.m.m g.g.g.g

  • Repeat many times

  • Add default route to classroom router

    • next hop is backbone router

      ip route0.0.0.0 0.0.0.0 g.g.g.g


Test connectivity3
Test connectivity FreeBSD box

  • All routers can reach all PCs

  • All PCs can reach all backbone IP addresses

  • All PCs can reach PCs in other rows

  • Test with traceroute

  • All static routes have now been added on classroom router


Edit freebsd etc rc conf

On production machines, add lines to /etc/rc.conf to configure network on reboot

hostname="porcupine.tomato.example"

ifconfig_fxp0="inet X.X.X.X netmask Y.Y.Y.Y"

defaultrouter=”G.G.G.G"

See /etc/default/rc.conf for more information

Edit FreeBSD /etc/rc.conf


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