Tài liệu giảng dạy CCNA - module 03 chapter 11-Advanced Routing Protocol Topics

1
Module 03 Routing Protocol
Chapter 11
Advanced Routing Protocol Topics
2
Table of Content
1
Route Summarization and Variable-Length Subnet Masks
2
Classless Routing Protocols and Classless Routing
3
1. Route Summarization and
Variable-Length Subnet Masks
4
Issues with IP Addressing

IP addressing crisis

As early as 1992, the IETF identified two specific concerns:

IP address exhaustion

Routing table growth
U N I V E R S I T Y
U N I V E R S I T Y
Internet
5
IP Addressing Solutions

Short term to extension to IPv4


Subneting masking: RFCs 950, 1812

Variable-length subnet masks: RFC 1812

Classless interdomain routing: RFCs 1518,
1519, 2050

Address allocation for private Internets: RFC
1918

Network Address Translation: RFC 1631

Route summarization: RFC 1518

Ultimate solution: IPv6 128-bit address
space
6
What is VLSM ?

Subnet 172.16.14.0/24 is divided into smaller subnets (Sub-
subnet):

Subnet with one mask at first (/27)

Further subnet one of these subnets not used elsewhere (/30)
172.16.0.0/16
172.16.14.32/27
172.16.14. 64/27
172.16.14.96/27
C

B
A
HQ
172.16.1.0/24
172
.16.
2.0/
24
HQ
172.16.14.136/30
172.16.14.132/30
172.16.14.140/30
7
VLSM is supported

Open Shortest Path First (OSPF).

Integrated Intermediate System to Intermediate System
(Integrated IS-IS).

Enhanced Interior Gateway Routing Protocol (EIGRP).

RIP v2.

Static routing.
8
A waste of space
9
When to use VLSM?
10

Calculating subnets with VLSM
11
Calculating subnets with VLSM (2)
Derived from the
172.16.32.0/20 Subnet
172.16.33.0/30
172.16.32.0/26
172.16.32.64/26
172.16.32.128/26
172.16.32.192/26
26-Bit Mask (62 Hosts)
Derived from the
172.16.33.0/26 Subnet
30-Bit Mask (2 Hosts)
172.16.33.12/30
172.16.33.8/30
172.16.33.4/30
12
Exercise Calculating subnets with
VLSM
60 Hosts 12 Hosts 12 Hosts
Using VLSMs, define appropriate subnets for addressing
the networks using 192.168.10.0/24.
28 Hosts
KL
Sydney
Perth
Singapore
13
Exercise Calculating subnets with

VLSM
60 Hosts 12 Hosts 12 Hosts
192.168.10.0/24
KL
Sydney
Perth
Singapore
192.168.10.64/27
192.168.10.128/30
192.168.10.132/30
192.168.10.136/30
28 Hosts
192.168.10.0/26 192.168.10.96/28 192.168.10.112/28
14
Route aggregation with VLSM
KL
Sydney
Perth
Singapore
192.168.48.0/24
192.168.49.0/24
192.168.50.0/24
192.168.51.0/24
192.168.52.0/24
192.168.53.0/24
192.168.54.0/24
192.168.55.0/24
192.168.56.0/24
192.168.57.0/24
192.168.63.0/24

1
9
2
.
1
6
8
.
5
6
.
0
/
2
1
192.168.52.0/22

1
9
2
.
1
6
8
.
4
8
.
0

/
2
0
192.168.48.0/22
Upstream
provider
Upstream
provider
Route summarization reduces routing table size by
aggregating routes to multiple networks into one
supernet
15
Route summarization example
16
Configuring VLSM
192.168.10.112/28
60 Hosts 12 Hosts 12 Hosts
192.168.10.0/24
KL
Sydney
Perth
Singapore
192.168.10.64/27
192.168.10.128/30
192.168.10.132/30
192.168.10.136/30
28 Hosts
192.168.10.0/26 192.168.10.96/28
S0
10.137

S0 10.137
17
2. CLASSLESS ROUTING
PROTOCOLS AND CLASSLESS
ROUTING
18
Classless and Classful Routing
Protocols

Classful routing protocols do not transmit the mask
information along with the subnet number.

Classless routing protocols do transmit mask information.
They support some advanced features such as VLSM and
summarization.
19
Autosummarization

When a router has interfaces in more than one Class A, B,
or C network, it advertises a single route for an entire Class
A, B, or C network into the other network. This feature is
called autosummarization.

When advertised on an interface whose IP address is not in
network X, routes related to subnets in network X are
summarized and advertised as one route. That route is for
the entire Class A, B, or C network X.

Classful routing protocols perform autosummarization by
default.

20
Autosumarization
Subnet mask: 255.255.255.0
10.3.4.0
10.3.5.0
10.3.6.0
10.3.7.0
172.16.3.0
172.16.1.0
I only know about
network 10.0.0.0 –
No subnets!
21
Autosummarization Pitfalls
10.3.4.0
10.3.5.0
10.3.6.0
10.3.7.0
172.16.3.0
172.16.1.0
Which route to
network 10.0.0.0
do I believe ?
10.2.1.0
10.2.2.0
10.2.3.0
10.2.4.0
172.16.1.0
Subnet mask: 255.255.255.0
22

Default route
Rest Net
Frame Relay
168.13.100.0
168.13.1.0/24
168.13.2.0
168.13.3.0
Dist 1
R 1
R 2
R 3
168.13.100.1
10.1.1.1
168.13.1.1
168.13.100.1
23
Ip route command
R1(config)# ip route 0.0.0.0 0.0.0.0 168.13.1.101
R1# show ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - 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 168.13.1.101 to network 0.0.0.0
168.13.0.0/24 is subnetted, 4 subnets
C 168.13.1.0 is directly connected, TokenRing0
R 168.13.3.0 [120/1] via 168.13.100.3, 00:00:05, Serial0.1

R 168.13.2.0 [120/1] via 168.13.100.2, 00:00:21, Serial0.1
C 168.13.100.0 is directly connected, Serial0.1
S* 0.0.0.0/0 [1/0] via 168.13.1.101
24
Ip route command (cont.)
R3# show ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - 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 168.13.100.1 to network 0.0.0.0
168.13.0.0/24 is subnetted, 4 subnets
R 168.13.1.0 [120/1] via 168.13.100.1, 00:00:13, Serial0.1
C 168.13.3.0 is directly connected, Ethernet0
R 168.13.2.0 [120/1] via 168.13.100.2, 00:00:06, Serial0.1
C 168.13.100.0 is directly connected, Serial0.1
25
Ip default-network command
R1(config)# ip default network 10.0.0.0
R1(config)# exit
R1# show ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - 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 168.13.1.101 to network 10.0.0.0
168.13.0.0/24 is subnetted, 5 subnets
R 168.13.200.0 [120/1] via 168.13.1.101, 00:00:12, TokenRing0
C 168.13.1.0 is directly connected, TokenRing0
R 168.13.3.0 [120/1] via 168.13.100.3, 00:00:00, Serial0.1
R 168.13.2.0 [120/1] via 168.13.100.2, 00:00:00, Serial0.1
C 168.13.100.0 is directly connected, Serial0.1
R* 10.0.0.0/8 [120/1] via 168.13.1.101, 00:00:12, TokenRing0