Lesson 9 - Depovere.com

flutteringevergreenNetworking and Communications

Oct 29, 2013 (3 years and 11 months ago)

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IP Routing

Static Routing

2003
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2004
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Information management

2

Groep T Leuven


Information department

2
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The Router


Router Interface is a physical connector that enables a
router to send or receive packets


Each interface connects to a separate network


Consist of socket or jack found on the outside of a
router


Types of router interfaces:


-
Ethernet


-
Fastethernet


-
Serial


-
DSL


-
ISDN


-
Cable

2003
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2004
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Information management

3

Groep T Leuven


Information department

3
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Routing Table


Routing table should contain at least 2 items


Destination address


Pointer to the destination

Network 10.1.1.0 is missing !

2003
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2004
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Information management

4

Groep T Leuven


Information department

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Routing Table

Router3#show ip route

Codes: C
-

connected, S
-

static, I
-

IGRP, R
-

RIP, M
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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, E
-

EGP


i
-

IS
-
IS, 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



10.0.0.0/24 is subnetted, 7 subnets

S 10.1.1.0 [1/0] via 10.1.4.1

S 10.1.2.0 [1/0] via 10.1.4.1

S 10.1.3.0 [1/0] via 10.1.4.1

C 10.1.4.0 is directly connected, Serial2/0

C 10.1.5.0 is directly connected, FastEthernet0/0

C 10.1.6.0 is directly connected, Serial3/0

S 10.1.7.0 [1/0] via 10.1.6.2

Router3#

2003
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2004
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Information management

5

Groep T Leuven


Information department

5
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Routing order


1.
Check for a connected network

2.
Search for a matching host route

3.
Search for a matching network route

4.
Search for a default gateway (last resort)

2003
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2004
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Information management

6

Groep T Leuven


Information department

6
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The router


As a packet travels from one networking device to another


-
The Source and Destination IP addresses
NEVER
change


-
The Source & Destination MAC addresses

CHANGE

as
packet is forwarded from one router to the next.


-
TTL field decrement by one until a value of zero is reached
at which point router discards packet (prevents packets from
endlessly traversing the network)

2003
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2004
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Information management

7

Groep T Leuven


Information department

7
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Router Path


step 1


PC1 Wants to send something to PC 2 here is part of
what happens


Step 1

-

PC1 encapsulates packet into a frame.
Frame contains R1’s destination MAC address

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2004
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Information management

8

Groep T Leuven


Information department

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Router Path


step 2

Step 2

-

R1 receives Ethernet frame.

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2004
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Information management

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Information department

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Router Path


step 2


Step 2

-

R1 receives Ethernet frame.


R1 sees that destination MAC address matches
its own MAC.


R1 then strips off Ethernet frame.


R1 Examines destination IP.


R1 consults routing table looking for destination
IP.


After finding destination IP in routing table, R1
now looks up next hop IP address.


R1 re
-
encapsulates IP packet with a new
Ethernet frame.


R1 forwards Ethernet packet out Fa0/1 interface.

2003
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2004
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Information management

10

Groep T Leuven


Information department

10
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Router Path


step 3

Step 3

-

Packet arrives at R2


R2 receives Ethernet frame


R2 sees that destination MAC address matches its own
MAC


R2 then strips off Ethernet frame


R2 Examines destination IP


R2 consults routing table looking for destination IP


After finding destination IP in routing table, R2 now looks
up next hop IP address


R2 re
-
encapsulates IP packet with a new data link frame


R2 forwards Ethernet packet out S0/0 interface

2003
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2004
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Information management

11

Groep T Leuven


Information department

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Router Path


step 4

Step 4

-

Packet arrives at R3


R3 receives PPP frame


R3 then strips off PPP frame


R3 Examines destination IP


R3 consults routing table looking for destination IP


After finding destination IP in routing table, R3 is directly
connected to destination via its fast Ethernet interface


R3 re
-
encapsulates IP packet with a new Ethernet frame


R3 forwards Ethernet packet out Fa0/0 interface

Step 5

-

IP packet arrives at PC2.


Frame is decapsulated & processed by upper layer
protocols.


2003
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2004
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Information management

12

Groep T Leuven


Information department

12
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Demo


packet tracer

2003
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2004
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Information management

13

Groep T Leuven


Information department

13
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Case studies


Summary routes


Default routes


Alternative routes


Floating static


Load sharing


Trouble shooting static routes

2003
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2004
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Information management

14

Groep T Leuven


Information department

14
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Exercise


Configure the routing that all traffic goes clock wise

10.1.0.0/24

10.5.0.0/24

10.2.0.0/24

10.3.0.0/24

10.4.0.0/24

10.6.0.0/24

10.7.0.0/24

64 kbps

128 kbps

16 kbps

.1

.1

.1

.1

.2

.2

.2

.2

.1

.1

.1

.2