Routing và Static Routes

Router Fundamentals

Router Components

- CPU
- RAM (running-config, routing table)
- NVRAM (startup-config)
- Flash (IOS image)
- ROM (bootstrap)
- Interfaces

Boot Process

1. POST (Power-On Self Test)
2. Load bootstrap từ ROM
3. Load IOS từ Flash
4. Load startup-config từ NVRAM
5. Nếu không có → Setup mode

Router Configuration

Initial Config

Router> enable
Router# configure terminal
Router(config)# hostname R1
R1(config)# enable secret Cisco123
R1(config)# line console 0
R1(config-line)# password Console123
R1(config-line)# login
R1(config-line)# logging synchronous
R1(config-line)# exit
R1(config)# line vty 0 4
R1(config-line)# password Vty123
R1(config-line)# login
R1(config-line)# transport input ssh
R1(config-line)# exit
R1(config)# ip domain-name abc.local
R1(config)# crypto key generate rsa modulus 2048
R1(config)# username admin privilege 15 secret Admin123
R1(config)# service password-encryption
R1(config)# banner motd # Authorized access only #
R1(config)# end
R1# write memory

Interface Configuration

R1(config)# interface gi0/0
R1(config-if)# description "WAN to ISP"
R1(config-if)# ip address 203.0.113.2 255.255.255.252
R1(config-if)# no shutdown
R1(config-if)# exit

R1(config)# interface gi0/1
R1(config-if)# description "LAN Gateway"
R1(config-if)# ip address 192.168.1.1 255.255.255.0
R1(config-if)# no shutdown
R1(config-if)# exit

# Verify
R1# show ip interface brief
R1# show interfaces gi0/0
R1# show ip interface gi0/0

Static Routing

Cấu trúc lệnh

ip route <network> <mask> {next-hop | exit-interface} [AD] [permanent]

AD (Administrative Distance):
- Connected: 0
- Static: 1
- eBGP: 20
- EIGRP: 90
- OSPF: 110
- RIP: 120
- iBGP: 200

Các loại Static Route

1. Next-hop route

R1(config)# ip route 192.168.2.0 255.255.255.0 10.0.0.2

2. Directly connected route

R1(config)# ip route 192.168.2.0 255.255.255.0 gi0/0

3. Fully specified route (khuyến nghị)

R1(config)# ip route 192.168.2.0 255.255.255.0 gi0/0 10.0.0.2

4. Default route

R1(config)# ip route 0.0.0.0 0.0.0.0 203.0.113.1

5. Host route

R1(config)# ip route 192.168.1.100 255.255.255.255 10.0.0.2

6. Floating static route (backup)

# AD cao hơn để làm backup
R1(config)# ip route 192.168.2.0 255.255.255.0 10.0.0.2 1
R1(config)# ip route 192.168.2.0 255.255.255.0 10.0.0.6 5

IPv4 Routing Table

Cấu trúc

Codes: C - Connected, S - Static, R - RIP, O - OSPF, D - EIGRP

Gateway of last resort is 203.0.113.1 to network 0.0.0.0

S*  0.0.0.0/0 [1/0] via 203.0.113.1
C   192.168.1.0/24 is directly connected, GigabitEthernet0/1
L   192.168.1.1/32 is directly connected, GigabitEthernet0/1
S   192.168.2.0/24 [1/0] via 10.0.0.2

Xem routing table

R1# show ip route
R1# show ip route static
R1# show ip route connected
R1# show ip route 192.168.1.0
R1# show ip route summary

Longest Prefix Match

Destination 192.168.1.100:
- 0.0.0.0/0 (default) - /0
- 192.168.1.0/24       - /24
- 192.168.1.100/32     - /32 ← Chọn route này

Rule: Prefix dài nhất thắng

IPv6 Static Routes

# Enable IPv6 routing
R1(config)# ipv6 unicast-routing

# Configure interface
R1(config)# interface gi0/0
R1(config-if)# ipv6 address 2001:db8:1::1/64
R1(config-if)# ipv6 enable
R1(config-if)# no shutdown
R1(config-if)# exit

# Static IPv6 route
R1(config)# ipv6 route 2001:db8:2::/64 2001:db8:1::2

# Default IPv6 route
R1(config)# ipv6 route ::/0 2001:db8:1::2

# Verify
R1# show ipv6 route
R1# show ipv6 interface brief
R1# show ipv6 interface gi0/0

NAT (Network Address Translation)

NAT Types

Static NAT: 1-1 mapping (private to public)
Dynamic NAT: Pool to pool
PAT (Overload): Many to 1 (most common)

Static NAT

R1(config)# ip nat inside source static 192.168.1.10 203.0.113.10

R1(config)# interface gi0/1
R1(config-if)# ip nat inside
R1(config-if)# exit

R1(config)# interface gi0/0
R1(config-if)# ip nat outside
R1(config-if)# exit

Dynamic NAT

# Define pool
R1(config)# ip nat pool MYPOOL 203.0.113.10 203.0.113.20 netmask 255.255.255.0

# ACL cho inside
R1(config)# access-list 1 permit 192.168.1.0 0.0.0.255

# NAT rule
R1(config)# ip nat inside source list 1 pool MYPOOL

# Apply to interfaces
R1(config)# interface gi0/1
R1(config-if)# ip nat inside
R1(config-if)# exit
R1(config)# interface gi0/0
R1(config-if)# ip nat outside

PAT (Overload)

# Với interface
R1(config)# ip nat inside source list 1 interface gi0/0 overload

# Với pool
R1(config)# ip nat inside source list 1 pool MYPOOL overload

# Verify
R1# show ip nat translations
R1# show ip nat statistics
R1# clear ip nat translation *

Port Forwarding

# Forward port 80 to internal server
R1(config)# ip nat inside source static tcp 192.168.1.100 80 203.0.113.10 80
R1(config)# ip nat inside source static tcp 192.168.1.100 443 203.0.113.10 443

DHCP

DHCP Server trên Router

# Enable service
R1(config)# service dhcp

# Exclude IPs
R1(config)# ip dhcp excluded-address 192.168.1.1 192.168.1.10
R1(config)# ip dhcp excluded-address 192.168.1.100 192.168.1.110

# DHCP Pool
R1(config)# ip dhcp pool LAN-POOL
R1(dhcp-config)# network 192.168.1.0 255.255.255.0
R1(dhcp-config)# default-router 192.168.1.1
R1(dhcp-config)# dns-server 8.8.8.8 8.8.4.4
R1(dhcp-config)# domain-name abc.local
R1(dhcp-config)# lease 7
R1(dhcp-config)# exit

# Static binding
R1(config)# ip dhcp pool PRINTER
R1(dhcp-config)# host 192.168.1.50 255.255.255.0
R1(dhcp-config)# hardware-address 0011.2233.4455
R1(dhcp-config)# client-name Printer
R1(dhcp-config)# default-router 192.168.1.1
R1(dhcp-config)# exit

# Verify
R1# show ip dhcp binding
R1# show ip dhcp pool
R1# show ip dhcp statistics

DHCP Relay

# Trên router (khi DHCP server ở subnet khác)
R1(config)# interface gi0/1.10
R1(config-subif)# ip helper-address 10.0.0.10
R1(config-subif)# exit

Bài tập thực hành

Hãy cấu hình routing và NAT!