Extended IP Address

Ii. Expand the I P address

The rapid development of the Internet is incredible. This rapid development has led to two major address challenges:
* IP address depletion
* Route table growth and manageability

IP addressing solution:
Enable more hierarchical layers in IP addresses to reduce IP address consumption and Internet route table entries. These solutions include:
* Subnet Mask
* Private Network Address Allocation
* Network Address Translation (NAT)
* Systematic addressing
* Variable Length Subnet Mask (VLSM)
* Route Induction
* Classless Inter-Domain Routing (CIDR)

IP address category:
The first byte (decimal) of an address.
1 ~ 126A
128 ~ 191B class
192 ~ 223C class
224 ~ 239D class
240 ~ 255E class
Class D addresses are not widely used. They are multicast addresses. Some routing protocols use the following Class D multicast addresses:
OSPF-----224.0.0.5 and 224.0.0.6
R00002 ----- 224.0.0.9
EIGRP----224.0.0.10

Systematic editing address:
Systematic addressing is like making a phone call. Every telephone Bureau does not need to know the country's phone number. If the first phone number is not 0, the switchboard will find the link in its telephone entry and take it over, if it is 0, it will be regarded as the zone number, for example, 0791-6221155. It will send this information to the Nanchang telephone Bureau (0791) and the Nanchang telephone Bureau will find the 6221155 link and connect it, in this way, your switchboard does not need to have entries in other places, so that others can have a meal. J. The principle can also be used in routers.

Advantages of systematic addressing:
* Reduce the number of Route entries
Routing induction is a method that uses an IP address to represent a set of IP addresses after systematic addressing planning. by summarizing the routes, we can maintain the route table entries as manageable, which can bring the following benefits:
------ Improve routing (forwarding) efficiency;
------ When the route table is re-computed or a match is retrieved through the route table entry, the number of CPU cycles required is reduced;
------ Reduces the memory demand for Routers
------ Faster convergence when the network changes
------ Easy troubleshooting

* Valid Address Allocation
Systematic addressing enables us to use all possible addresses because our address groups are continuous;

Variable Length Subnet Mask (VLSM)
VLSM provides the ability to include multiple subnet masks in A primary class (class A, Class B, and class C) network, as well as the ability to subscribe to one subnet. It has the following advantages:
* More effective use of IP addresses-If VLSM is not used, the company will be restricted to using only one subnet mask for A, B, and C network numbers;
* Better routing induction capability-VLSM allows more system layers in the addressing plan, so better routing induction can be performed in the route table.

Route Induction
In large interconnected networks, there are hundreds of thousands of networks. In this environment, you generally do not want the router to save all these routes in its routing table. Route induction (also called route aggregation or upernetting) can reduce the number of Route entries that must be saved by the router, because it represents a series of network numbers in an inductive address.
Another advantage of routing induction in large and complex networks is that it can protect other routers from changes in the network topology.

Routing induction is feasible and most effective only when a correct address planning is used. In a subnet environment, when the network address is a continuous block in the form of 2, routing induction is the most effective.

The routing selection protocol summarizes or aggregates routes based on the shared network address. Classless routing protocol-OSPF and OSPF-supports subnet-based routing, including address-based routing of VLSM compilers. The classless routing protocols-r1_1 and IGRP-automatically generalize routes on the boundaries of a classless network. The classless routing protocol does not support route induction on any other bit boundary, but does not support route induction on any bit boundary.
Because there are fewer route table entries, routing induction can reduce the consumption of vro memory and reduce the network traffic caused by the route selection protocol. To make routing induction in the network work correctly, the following requirements must be met:
* Multiple IP addresses must share the same high bit;
* The Route Selection protocol must be based on the 32-bit IP address and the length of the 32-bit prefix.
* Route update must transmit the prefix length (subnet mask) along with a 32-bit IP address.

Route induction in a Cisco Router
CISCO manages route induction using the following two methods:
* Send route Summary
* Select a route from route Induction

A subnet with Discontinuous addresses refers to some subnets in the same primary-class network separated by other different primary-class networks.

Route Selection protocol support for Route Induction
Does the Protocol automatically sum up when there is a network boundary? Can automatic induction be disabled? Can automatic induction be performed out of the category network boundary?
R1_1: No
Is r1_2
IGRP?
Is
OSPF No -- yes

Classless Inter-Domain Routing (CIDR)
CIDR is a technology developed to help mitigate the problem of increasing IP addresses and route tables. The concept of CIDR is that multiple Class C address blocks can be combined or aggregated to generate a larger class I P address set (that is, more hosts are allowed ). The block-based Class C address is assigned to each ISP.

Use a serial IP Address
To enable IP processing on a serial interface without assigning a specific ip address to the interface, you can use the "IP unnumbered type number" interface to configure commands. In this command, "type number" is another interface with an assigned IP address on the router (this interface is called a specified interface or a reference interface, that is, the type and number of the interface from which the unnumbered interface borrows the IP address. It cannot be another unnumbered interface. If you want to disable the I P processing function in the serial interface, you can use the NO form of this command.

No number interface restrictions:
* Serial interfaces using HDLC, PPP, LAPB, and SLIP protocols and tunnel interfaces can be Unnumbered. It cannot be in X. 25. Use the unnumbered interface to configure commands on the SMDS interface of the exchange-type multi-region data service.
* We cannot use the PING command to determine whether the unnumbered interface has been UP, because the interface has no address. SNMP can remotely monitor the status of this interface.
Example:
Interface Ethernet0 Ip address 10.1.1.1 255.255.255.0! Interface Serial0 ip unnumbered Ethernet0

Helper Address)

Vro does not distribute broadcasts. The help address helps the client establish contact with the server by directly forwarding these broadcast packets to the target server.

The help address command changes the Broadcast Destination Address to the single-point transfer room delivery address (or a targeted broadcast-this broadcast in a subnet ), enables the broadcast message to be routed to a specific destination instead of all places.

Use the "ip helper-address" interface to configure the command to configure an interface that may receive broadcasts. In this command, "ADDRESS" refers to the destination ADDRESS used to forward User Datagram Protocol (UDP) broadcasts. The specified address can be a single point transfer address or a targeted broadcast address of the remote server.

If the "ip helper-address" command is defined, the forwarding function for eight default UDP ports is automatically enabled, which are: TFTP (69), DNS (53), time (37), NETBIOS service (137), n etbios datagram Service (138), BOOTP server (67), BOOTP client (68) and the access control system TACACS (49 ).
If the "ip helper-address" command is defined and the "ip forward-protocol udp" command is defined for the eight u d p ports, then the broadcast data packets destined for these eight UDP ports are automatically forwarded.

"Ip forward-protocol" Description:
"Ip forward-protocol" command description
UdpUDP-Transport Layer Protocol
Port (optional) when the "udp" keyword is specified, you can define the UDP destination port number or port name
Nd Network Disk; an old protocol used by the diskless Sun Workstation
Sdns Network Security Protocol

Instance:
Interface Ethernet 0 Ip address 172.16.1.100 255.255.255.0 Ip helper-address 172.16.2.2! Ip forward-protocol udp 3000no ip forward-protocol udp tftp

The "ip helper-address" command must be configured on the router interface that receives the original customer broadcast packet.
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