TP-Link T2600G-28MPS T2600G-28MPSUN V1 User Guide - Page 190

Routing

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Chapter 10 Routing Routing is the method by which the host or gateway decides where to send the datagram. Routing is the task of finding a path from a sender to a desired destination. It may be able to send the datagram directly to the destination, if that destination is on one of the networks that are directly connected to the host or gateway. However, what if the destination is not directly reachable? The host or gateway will attempt to send the datagram to a gateway that is nearer to the destination. The goal of a routing protocol is very simple: It is to supply the information that is needed to do routing. The Routing module is mainly for routing management configuration of the switch, including the following submenus: Interface, Routing Table, Static Routing, DHCP Server, DHCP Relay and ARP. 10.1 Interface Interface is a virtual interface in Layer 3 mode and mainly used for realizing the Layer 3 connectivity between VLANs or routed ports. Each VLAN interface is corresponding to one VLAN. Each routed port is corresponding to one port. Each Layer 3 port-channel is corresponding to one port channel. Loopback Interface is purely software implemented. Interface has its own IP address and subnet mask to identify the subnet it belongs to, and it works as the gateway of the subnet to forward Layer 3 IP packets. Introduction of IPv6 Address IPv6 (Internet Protocol version 6), also called IPng (IP next generation), was developed by the IETF (Internet Engineering Task Force) as the successor to IPv4 (Internet Protocol version 4). Compared with IPv4, IPv6 increases the IP address size from 32 bits to 128 bits; this solves the IPv4 address exhaustion problem.  IPv6 features IPv6 has the following features: 1. Adequate address space: The source and destination IPv6 addresses are both 128 bits (16 bytes) long. IPv6 can provide 3.4 x 1038 addresses to completely meet the requirements of hierarchical address division as well as allocation of public and private addresses. 2. Header format simplification: IPv6 cuts down some IPv4 header fields or move them to IPv6 extension headers to reduce the load of basic IPv6 headers, thus making IPv6 packet handling simple and improving the forwarding efficiency. Although the IPv6 address size is four times that of IPv4 addresses, the size of basic IPv6 headers is 40 bytes and is only twice that of IPv4 headers (excluding the Options field). 3. Flexible extension headers: IPv6 cancels the Options field in IPv4 packets but introduces multiple extension headers. In this way, IPv6 enhances the flexibility greatly to provide scalability for IP while improving the handling efficiency. The Options field in IPv4 packets contains 40 bytes at most, while the size of IPv6 extension headers is restricted by that of IPv6 packets. 4. Built-in security: IPv6 uses IPSec as its standard extension header to provide end-to-end security. This feature provides a standard for network security solutions and improves the interoperability between different IPv6 applications. 179

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Chapter 10 Routing
Routing is the method by which the host or gateway decides where to send the datagram. Routing
is the task of finding a path from a sender to a desired destination. It may be able to send the
datagram directly to the destination, if that destination is on one of the networks that are directly
connected to the host or gateway. However, what if the destination is not directly reachable? The
host or gateway will attempt to send the datagram to a gateway that is nearer to the destination.
The goal of a routing protocol is very simple: It is to supply the information that is needed to do
routing.
The Routing module is mainly for routing management configuration of the switch, including the
following submenus:
Interface
,
Routing Table
,
Static Routing
,
DHCP Server
,
DHCP Relay
and
ARP
.
10.1 Interface
Interface is a virtual interface in Layer 3 mode and mainly used for realizing the Layer 3
connectivity between VLANs or routed ports. Each VLAN interface is corresponding to one VLAN.
Each routed port is corresponding to one port. Each Layer 3 port-channel is corresponding to one
port channel. Loopback Interface is purely software implemented. Interface has its own IP address
and subnet mask to identify the subnet it belongs to, and it works as the gateway of the subnet to
forward Layer 3 IP packets.
Introduction of IPv6 Address
IPv6 (Internet Protocol version 6), also called IPng (IP next generation), was developed by the
IETF (Internet Engineering Task Force) as the successor to IPv4 (Internet Protocol version 4).
Compared with IPv4, IPv6 increases the IP address size from 32 bits to 128 bits; this solves the
IPv4 address exhaustion problem.
IPv6 features
IPv6 has the following features:
1.
Adequate address space:
The source and destination IPv6 addresses are both 128 bits (16
bytes) long. IPv6 can provide 3.4 x 10
38
addresses to completely meet the requirements of
hierarchical address division as well as allocation of public and private addresses.
2.
Header format simplification:
IPv6 cuts down some IPv4 header fields or move them to IPv6
extension headers to reduce the load of basic IPv6 headers, thus making IPv6 packet handling
simple and improving the forwarding efficiency. Although the IPv6 address size is four times
that of IPv4 addresses, the size of basic IPv6 headers is 40 bytes and is only twice that of IPv4
headers (excluding the Options field).
3.
Flexible extension headers:
IPv6 cancels the Options field in IPv4 packets but introduces
multiple extension headers. In this way, IPv6 enhances the flexibility greatly to provide
scalability for IP while improving the handling efficiency. The Options field in IPv4 packets
contains 40 bytes at most, while the size of IPv6 extension headers is restricted by that of IPv6
packets.
4.
Built-in security:
IPv6 uses IPSec as its standard extension header to provide end-to-end
security. This feature provides a standard for network security solutions and improves the
interoperability between different IPv6 applications.
179