Configure Static Routing Protocal in Cisco Packet Tracer

How to Configure Static Routing Protocol

By

Apex TG India Pvt Ltdhttp://www.apextgi.in

http://www.apextgi.in/

2

Routing Types

3

Static Route Operation

Hoboken#show ip route

Codes: C - connected, S - static,

S 172.16.1.0/24 [1/0] is directly connected, Serial0

C 192.168.2.0/24 is directly connected, Ethernet0

4

ip route command

RTR(config)# ip route prefix mask {address | interface} [distance] [tag tag] [permanent]

prefix IP route prefix for the destination.

mask Prefix mask for the destination.

address IP address of the “next hop” that can be used to reach that network.

interface Network interface to use (exit-interface)

distance (Optional) An administrative distance.

tag tag (Optional) Tag value that can be used as a "match" value for controlling redistribution via route maps. (CCNP Advanced Routing)

Permanent (Optional) Specifies that the route will not be removed, even if the interface shuts down. (CCNP Advanced Routing)

5


• If the exit interface (gateway) is “down” the static route will not be put in the routing table.

6


• If the router cannot reach the outgoing interface that is being used in the route, the route will not be installed in the routing table.

• This means if that interface is down, the route will not be placed in the routing table.

7

Administrative Distance and Metric

[ administrative distance / routing metric (or cost) ]

The cost for all static routes is “0” The default administrative distance for static

routes is “1”

Hoboken#show ip route


S 172.16.1.0/24 [1/0] is directly connected, Serial0


8

Administrative Distance

Administrative Distance is the “trustworthiness” of the routing information. Lower the administrative distance the more trustworthy the information. If the router hears about a route to the same network from more than one source it will

use the administrative distance to decide which route to put in the routing table.

9

Examples from the curriculum

10


• Two choices.

• We will see the differences in a moment.

11


• The network 0.0.0.0 and mask 0.0.0.0 are known as a “default route”

• Can be written 0.0.0.0/0

• Known as a “quad zero” route”

• More later

12

Static Routing

Some extra information on static routing that is not in the curriculum

13

Static Routing

Router(config)#ip route destination-prefix destination-prefix-mask {address | interface} [distance] [tag tag] [permanent]

14

Static Routing

Configuring static routes Routers do not need to configure static routes for their own directly connected

networks. We need to configure static routes for networks this router needs to reach. We will need to configure static routes for the other routers as well, as “routing

information about a path from one network to another does not provide routing information about the reverse, or return path.”

Convergence – When all the routers in the network (AS) have accurate and consistent information, so that proper routing and packet forwarding can take place.

Convergence will not happen until all the routers have complete and accurate routing information, meaning we must configure static routes on all the routers before packets will be correctly delivered.

172.16.0.0/16 192.168.1.0/24

.1 .1.2 .2

RTA RTB RTC192.168.2.0/24

.1 .1

10.1.0.0/16

s0 s0 s1s1e0 e0

15

Basic static route example Be sure to use the proper subnet mask!

RTA(config)#ip route 192.168.1.0 255.255.255.0 172.16.0.2

RTA#show ip route


C 172.16.0.0/16 is directly connected, Serial0

S 192.168.1.0/24 [1/0] via 172.16.0.2


Network/subnet route

Intermediate-Address (usually “next-hop”)

172.16.0.0/16 192.168.1.0/24

.1 .1.2 .2

RTA RTB RTC192.168.2.0/24

.1 .1

10.1.0.0/16

s0 s0 s1s1e0 e0

Static Routing

16

Basic static route example (continued) [1/0] – [ Administrative Distance / Metric ] Administrative Distance – This is the “trustworthiness” of the routing information. The default

administrative distance of static routes is 1. The Administrative Distance of a directly connected route is 0. Lower the AD the more trustworthy. If the router learns about a route to a network from more than one source, it will install the route

with the lower administrative distance in the routing table.


RTA#show ip route



S 192.168.1.0/24 [1/0] via 172.16.0.2


172.16.0.0/16 192.168.1.0/24

.1 .1.2 .2

RTA RTB RTC192.168.2.0/24

.1 .1

10.1.0.0/16

s0 s0 s1s1e0 e0

Static Routing

17

Basic static route example (continued) [1/0] – [ Administrative Distance / Metric ] Metric – This is the “cost” of getting to this route, I.e. how far away this network is. The lower the cost, the closer the network. Static routes always show a cost of “0” even if it was configured with the intermediate address is

multiple-hops away. Much more later.


RTA#show ip route



S 192.168.1.0/24 [1/0] via 172.16.0.2


172.16.0.0/16 192.168.1.0/24

.1 .1.2 .2

RTA RTB RTC192.168.2.0/24

.1 .1

10.1.0.0/16

s0 s0 s1s1e0 e0

Static Routing

18

Recursive Lookup The router knows it can get to 192.168.1.0/24 network by forwarding the packets to the router at

the ip address of 172.16.0.2 How does the router know how to get to the ip address 172.16.0.2? It does a recursive lookup – first (1) by looking up the 192.168.1.0/24 network and finding it

needs to forward the packet to 172.16.0.2 – the router then (2) looks up the 172.16.0.0 network and sees it can forward it out the interface Serial 0.


RTA#show ip route



S 192.168.1.0/24 [1/0] via 172.16.0.2


172.16.0.0/16 192.168.1.0/24

.1 .1.2 .2

RTA RTB RTC192.168.2.0/24

.1 .1

10.1.0.0/16

s0 s0 s1s1e0 e0

1

2

Static Routing

19

Static Routes and the Routing Table Process Notice that the static route is entered into the routing table by the routing table process (debug ip routing) with

a metric of 0.

172.16.0.0/16 192.168.1.0/24

.1 .1.2 .2

RTA RTB RTC192.168.2.0/24

.1 .1

10.1.0.0/16

s0 s0 s1s1e0 e0

RTA#debug ip routing

IP routing debugging is on

RTA#conf t

Enter configuration commands, one per line. End with CNTL/Z.


05:53:48: RT: add 192.168.1.0/24 via 172.16.0.2, static metric [1/0]



RTA(config)#undebug all

Static Routing

20

Configuring all of the static routes Notice that the intermediate-address is always the next-hop ip address. This does not always have to be the case, and we will look at other options in the presentation

on Static Routes- Additional Information Good idea to do a “copy running-config startup-config” if everything is working right. To verify the routes are in there, you can do a:

Router# show running-config

172.16.0.0/16 192.168.1.0/24

.1 .1.2 .2

RTA RTB RTC192.168.2.0/24

.1 .1

10.1.0.0/16

s0 s0 s1s1e0 e0



RTB(config)#ip route 192.168.2.0 255.255.255.0 172.16.0.1

RTB(config)#ip route 10.1.0.0 255.255.0.0 192.168.1.2

RTC(config)#ip route 192.168.2.0 255.255.255.0 192.168.1.1

RTC(config)#ip route 172.16.0.0 255.255.0.0 192.168.1.1

Static Routing

21

172.16.0.0/16 192.168.1.0/24

.1 .1.2 .2

RTA RTB RTC192.168.2.0/24

.1 .1

10.1.0.0/16

s0 s0 s1s1e0 e0



RTA#show ip route



10.0.0.0/16 is subnetted, 1 subnets

S 10.1.0.0 [1/0] via 172.16.0.2

S 192.168.1.0/24 [1/0] via 172.16.0.2


RTA#ping 10.1.0.1

!!!!!

RTA#ping 192.168.1.2

!!!!!

RTA#ping 192.168.1.1

!!!!!

Static Routing

22

Recursive Lookup The router knows it can get to 192.168.1.0/24 network by forwarding the packets to the router at

the ip address of 172.16.0.2 How does the router know how to get to the ip address 172.16.0.2? It does a recursive lookup – first (1) by looking up the 192.168.1.0/24 network and finding it

needs to forward the packet to 172.16.0.2 – the router then (2) looks up the 172.16.0.0 network and sees it can forward it out the interface Serial 0.


RTA#show ip route



S 192.168.1.0/24 [1/0] via 172.16.0.2


172.16.0.0/16 192.168.1.0/24

.1 .1.2 .2

RTA RTB RTC192.168.2.0/24

.1 .1

10.1.0.0/16

s0 s0 s1s1e0 e0

1

2

Static Routing – Recursive Lookups

23

Recursive Lookup (continued) We can take this even further. One route can be used to resolve the route of another. It doesn’t matter how the routes are resolved, whether they are directly connected, static or

dynamic. Note: If an intermediate address cannot be resolved, that route and any routes it affects are not

installed in the routing table.


RTA#show ip route



S 192.168.1.0/24 [1/0] via 172.16.0.2

S 10.1.0.0/16 [1/0] via 192.168.1.2


172.16.0.0/16 192.168.1.0/24

.1 .1.2 .2

RTA RTB RTC192.168.2.0/24

.1 .1

10.1.0.0/16

s0 s0 s1s1e0 e0

1

2

3


24

Note regarding recursive route lookups Every route that does not reference an exit-interface must finally be resolved via a

route with an interface descriptor reference in the corresponding path descriptor – a route with an exit-interface.

Static routes cannot be recursively resolved and will not be in the routing table. Consider these three static routes:

Route1: ip route 10.1.0.0 255.255.0.0 20.1.1.1 Route2: ip route 20.1.0.0 255.255.0.0 30.1.1.1 Route3: ip route 30.1.0.0 255.255.0.0 10.1.1.1

Route1 is resolved by Route2 which is resolved by Route3. None of these routes are finally resolved via a route with an exit-interface. This leads to endless recursion. The routing table process will not permit these static routes to be entered in the routing

table. Note: Static default routes (coming soon) can never be resolved via another default

route. (later)


25

Static Routes and the Routing Table Process Notice that the static route is entered into the routing table by the routing table process

(debug ip routing) with a metric of 0.

172.16.0.0/16 192.168.1.0/24

.1 .1.2 .2

RTA RTB RTC192.168.2.0/24

.1 .1

10.1.0.0/16

s0 s0 s1s1e0 e0

RTA#debug ip routing

IP routing debugging is on

RTA#conf t

Enter configuration commands, one per line. End with CNTL/Z.





RTA(config)#undebug all

Static Routing – Routing Table Process

26

Need only to use only an exit interface. For point-to-point serial interfaces, the next-hop address in the routing table is never

used by the packet-delivery procedure, so it is not needed. (It could even reference a bogus IP address.)

Notice that the static route appears in the routing table as directly connected, however it is still a static route with an administrative distance of 1.

172.16.0.0/16 192.168.1.0/24

.1 .1.2 .2

RTA RTB RTC192.168.2.0/24

.1 .1

10.1.0.0/16

s0 s0 s1s1e0 e0

RTA(config)#ip route 192.168.1.0 255.255.255.0 serial 0

RTA#show ip route



S 192.168.1.0/24 is directly connected, Serial0


Static Routing – Point-to-Point Links

27

Using an intermediate address instead of an exit-interface:

If an intermediate address is used on a static route via a point-to-point link, it is only used to find the exit-interface,

This recursive lookup is unnecessary and takes extra processing.


RTA#show ip route



S 192.168.1.0/24 [1/0] via 172.16.0.2


172.16.0.0/16 192.168.1.0/24

.1 .1.2 .2

RTA RTB RTC192.168.2.0/24

.1 .1

10.1.0.0/16

s0 s0 s1s1e0 e0

1

2

Static Routing – Point-to-Point Links

28

Using both an intermediate address instead and an exit-interface: Notice we changed 172.16.0.0 to an Ethernet link. Static routes via broadcast links, it is best to use both an exit interface and intermediate

address. This saves the router from having to do a recursive route lookup for the intermediate

address of 172.16.0.2, knowing the exit interface is Ethernet 0.

172.16.0.0/16 192.168.1.0/24

.1 .1.2 .2

RTA RTB RTC192.168.2.0/24

.1 .1

10.1.0.0/16

s0 s0 s1s1e0 e0

RTA(config)#ip route 192.168.1.0 255.255.255.0 eth 1 172.16.0.2

RTA#show ip route



S 192.168.1.0/24 [1/0] via 172.16.0.2 Ethernet1


e1 e0

Static Routing – Ethernet interfaces

29

Static Route Rule of Thumb

Static routes via point-to-point links

It is best to configure static routes with only the exit interface.

For point-to-point serial interfaces, the next-hop address in the routing table is never used by the packet-delivery procedure, so it is not needed. (It could even reference a bogus IP address.)

Static routes via broadcast networks such as Ethernet

It is best to configure static routes with both the next-hop address and the exit-interface.

Using only an intermediate address

“What about static routes referencing only intermediate network address? In short, try to avoid using them. The reason is that these static routes are not bound to any interface, rely on intermediate address resolvability, and thus converge more slowly. They can also create unexpected routing loops.” Alex Zinin, Cisco IP Routing

NOTE: Most of our examples in this course do not follow either of these rules-of-thumb – but you may want to use it on your network.

30

Static routes in the real-world Soon we will learn about dynamic routing protocols (RIP, etc.), where routers can learn

automatically about networks, without the manual configuration of static routes. Does this mean that static routes are never used in the real-world? No! Static routes are used in conjunction with dynamic routing protocols. It is common to use a static route where using a dynamic routing protocols would have

disadvantages or where it just not needed.

Common uses for Static Routes

31

Static routes in the real-world (continued) In the example above, there is only one route, link, between Cabrillo College’s network and the

ISP. When there is only a single route to a network, this is known as a stub network. It is very common for the ISP to have a static route pointing to it’s customers’ networks, in this

case Cabrillo College.

Cabrillo College

ISP

10.1.1.2/24

10.1.1.1/24

172.16.0.0/16

ip route 172.16.0.0 255.255.0.0 10.1.1.2


32

Static routes in the real-world (continued) What about Cabrillo College and sending packets to the ISP – packets going to the Internet? It is also common for customer networks to use a special kind of static route, known as a default static route. Of course we will examine this later throughout the rest of this course, but for now we specify the network and

mask as “0.0.0.0 0.0.0.0” (pronounced “quad-zero”). This tells the router to forward all packets to this next-hop address (or exit interface) that do not have an explicit

route in the routing table.

Cabrillo College

ISP

10.1.1.2/24

10.1.1.1/24

172.16.0.0/16

ip route 172.16.0.0 255.255.0.0 10.1.1.2

ip route 0.0.0.0 0.0.0.0 10.1.1.1

Default


33 Any packets not matching the routes 172.16.0.0/16 or 10.1.1.0/24 are sent to the router 10.1.1.1 –

where it is now their “problem.”

Cabrillo College

ISP

10.1.1.2/24

10.1.1.1/24

172.16.0.0/16

ip route 172.16.0.0 255.255.0.0 10.1.1.2

ip route 0.0.0.0 0.0.0.0 10.1.1.1

RTB#show ip route

Gateway of last resort is 10.1.1.1 to network 0.0.0.0


10.0.0.0/24 is subnetted, 1 subnets

C 10.1.1.0 is directly connected, Serial1

S* 0.0.0.0/0 [1/0] via 10.1.1.1

Default


34

Summarizing static routes

There are many times when a single static route can replace several static routes.

In other words, summarizing several static routes into a single static route.

Host 1

Host 2 Host 3

Hub

Hub Hub

S0 S0

S0 S1

E0 E0

E0

172.16.2.0/24

172.16.3.0/24

172.16.1.0/24

192.168.1.0/24

192.168.2.0/24

SanJose2

SanJose1

Baypointe

.1

.1

.1

.1 .1

.2.2172.16.0.0/24

35

Baypointe Let’s configure three static routes on Baypointe using either an intermediate-address or exit interface:

Baypointe(config)# ip route 172.16.1.0 255.255.255.0 192.168.1.2



Host 1

Host 2 Host 3

Hub

Hub Hub

S0 S0

S0 S1

E0 E0

E0

172.16.2.0/24

172.16.3.0/24

172.16.1.0/24

192.168.1.0/24

192.168.2.0/24

SanJose2

SanJose1

Baypointe

.1

.1

.1

.1 .1

.2.2172.16.0.0/24


36

Baypointe The three static routes can be summarized into a single route:

Baypointe(config)# ip route 172.16.1.0 255.255.255.0 192.168.1.2Baypointe(config)# ip route 172.16.2.0 255.255.255.0 192.168.1.2 Baypointe(config)# ip route 172.16.3.0 255.255.255.0 192.168.1.2

Summarized route:


The summarized route will now include all three subnets! Be sure to use the proper mask – 255.255.0.0! Using a 255.255.255.0 mask will only route for 172.16.0.0/24 subnet and not

172.16.1.0/24, 172.16.2.0/24 or 172.16.3.0/24.


37

Baypointe Summarized route:


Advantages: Fewer routes in the routing table – faster routing table lookup. Subnets can be added and deleted on 172.16.0.0 network without having to change static

route on Baypointe router.

Host 1

Host 2 Host 3

Hub

Hub Hub

S0 S0

S0 S1

E0 E0

E0

172.16.2.0/24

172.16.3.0/24

172.16.1.0/24

192.168.1.0/24

192.168.2.0/24

SanJose2

SanJose1

Baypointe

.1

.1

.1

.1 .1

.2.2172.16.0.0/24


38

Verify static routes

Copy running-config startup-config

39

Ping and Traceroute to troubleshoot

Thanks

Say Connected for more chapters on Routing

Follow us on

Facebook Twitter Google+

https://www.facebook.com/pages/ApexTgi-Pvt-Ltd/353478941333744

https://twitter.com/ApextgiNoida

https://plus.google.com/b/116818519717421915276/+ApexTGIndiaPvtLtdNoida/posts

Technology

Configure Static Routing Protocal in Cisco Packet Tracer