Wan routing Basics

Network instance
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-A network-router-a ================= router-B-B network-
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| Region ---- LAN ---- → | region --- wide-area interconnected subnet --- → | region ---- LAN ----- → |

There is only one network adapter (one IP address) in the network. Any host can only directly access the machine in the subnetwork. A vro is equivalent to a host with multiple NICs. Each Nic can communicate directly with a subnet. As we know, the two networks are connected by establishing a WAN subnet. There are only two machines in this subnet, namely the routers on both sides. Of course, its subnet mask is 255.255.255.252. As long as the Seiral ports of vroa A and vrob B are in the same subnet and their Ethernet ports belong to the and B networks respectively, we have established A channel between the and B networks. As long as A host in Network A sets the gateway as router A, its information can be forwarded to Network B through router A and router B.
In this example, we use the most widely used Cisco 2501 router. the physical structure of this router is simple. The network interface only has two Serial ports and one Ethernet port, but supports the complete routing function. The protocol used is TCP/IP, because other protocols such as IPX and Netbeui are outdated.
Instance 1: connect a lan to B LAN through Cisco 2501

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Assume that the experiment conditions are as follows:
Network A: 202.96.199.0 -- 202.96.199.255
Network B: 202.97.76.0 -- 202.97.76.31
DNS Server: 202.96.199.2 (master), 202.96.199.3 (Backup)
Domain: xxx.com
Wan Interconnection: a subnet containing four IP addresses (two available IP addresses) is required,
Set to: 202.98.0.0 -- 202.98.0.3, where 202.98.0.1 is sent to Network A and 202.98.0.2 to Network B.
Interconnected leased line rate: 128 kbps

The specific network parameter allocation table is as follows:
Project A Network B
Network No. 202.96.199.0 202.97.76.0
Subnet Mask 255.255.255.0 255.255.255.255.255.255.255.255.255.255.
Domain xxx.com yyy.com
Ethernet address 202.96.199.1 202.97.76.1
IP address 202.98.0.1 202.98.0.2
The leased line speed is 128 kbps and left
Domain Name Server master: 202.96.199.2
Backup: 202.96.199.3 and left
First, enter the vro: connect your computer's serial port to the Console port of the vro and log on to the vro。 using software such as Netterm or Super Terminal.

Router> en:
Passwd: ****** (enter the super password)

Global configuration: (Network A and Network B are the same)

Router # conf terminal (switch to configuration status)
Router (config) # enable secret my-root-password (define a super password)
Router (config) # ip host Router-A (vro name defined, Network B is Router-B)
Router (config) # ip domain-name xxx.com (defines the domain name, Network B is yyy.com)
Router (config) # nameserver 202.96.199.2 (defines the Primary Domain Name Server)
Router (config) # nameserver 202.96.199.3 (defines the backup Domain Name Server)
Router (config) # ip classless
Router (config) # line vty 0 4
(Five telnet virtual terminals are defined, that is, five people can log on to the vrotelnet at the same time)
Router (config-line) # password my-telnet-password (defines the telnet password)
Router (config-line) # exit
Router (config) # exit

Address and route Configuration:
/****** A network vro ******/
Router-A # conf t (switch to configuration status)
Router-A (config) # int e0 (Ethernet 0 port configured)
Router-A (config-if) # description the LAN port link to my local network (port description)
Router-A (config-if) # ip add 202.96.199.1 255.255.255.0
(Defines the Ethernet IP address. The subnet mask is represented as a class C Network)
Router-A (config-if) # no shutdown (activation port)
Router-A (config-if) # exit
Router-A (config) # int s0 (configure the Serial 0 port)
Router-A (config-if) # description the WAN port link to Router-B (port description)
Router-A (config-if) # ip add 202.98.0.1 255.255.255.255.252 (define the ip address of the interconnected Wan)
Router-A (config-if) # bandwidth 128 (Port rate defined, unit: kbps)
Router-A (config-if) # no shutdown (activation port)
Router-A (config-if) # exit
Router-A (config) # ip route 202.97.76.0 255.255.255.255.202.98.0.2
(Define a static route to reach the peer LAN through the gateway, and the IP address is the peer Wan IP address)
Router-A (config) # exit
Router-A # wr m (save configuration)

/****** B network vro ******/
Router-B # conf t
Router-B (config) # int e0
Router-B (config-if) # description the LAN port link to my local network (port description)
Router-B (config-if) # ip add 202.97.76.1 too many requests
(Defines an Ethernet IP address. The subnet mask is a subnet with 32 addresses)
Router-B (config-if) # no shutdown
Router-B (config-if) # exit
Router-B (config) # int s0
Router-B (config-if) # description the WAN port link to Router-A (port description)
Router-B (config-if) # ip add 202.98.0.2 255.255.255.252
Router-B (config-if) # bandwidth 128
Router-B (config-if) # no shutdown
Router-B (config-if) # exit
Router-B (config) # ip route 202.96.199.0 route 255.255.0 202.98.0.1
(Define a static route to reach the peer LAN through the gateway, and the IP address is the peer Wan IP address)
Router-B (config) # exit
Router-B # wr m (save configuration)

Configuration complete.

Here is the configuration list of vrouters for Network A and Network B.
Router:
Router-A # sh run
Building Configuration...
Current configuration
Version 11.2:
Service udp-small-servers
Service tcp-small-servers
Hostname Router-
Enable secret test-
Ip subnet-zero
Interface Ethernet0
Description the LAN port link to my local network
Ip address 202.96.199.1 255.255.255.0
Interface Serial0
Description the WAN port link to Router-B
Ip address 202.98.0.1 255.255.255.252
Bandwidx 128
Interface Serial1
No ip address
Shutdown
Ip domain-name xxx.com
Ip name-server 202.96.199.2
Ip name-server 202.96.199.3
Ip classless
Ip route 202.97.76.0 255.255.255.255.202.98.0.2
Line con 0
Line aux 0
Line vty 0 4
Password telnet-
Login
End
Router-#
Rouer B:
Router-B # sh run
Building Configuration...
Current configuration
Version 11.2:
Service udp-small-servers
Service tcp-small-servers
Hostname Router-B
Enable secret test-B
Ip subnet-zero
Interface Ethernet0
Description the LAN port link to my local network
Ip address 202.97.76.1 too many requests
Interface Serial0
Description the WAN port link to Router-
Ip address 202.98.0.2 255.255.255.252
Bandwidx 128
Interface Serial1
No ip address
Shutdown
Ip domain-name yyy.com
Ip name-server 202.96.199.2
Ip name-server 202.96.199.3
Ip classless
Ip route 202.96.199.0 route 255.255.0 202.98.0.1
Line con 0
Line aux 0
Line vty 0 4
Password telnet-B
Login
End
Router-B #

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