requirements for internet gateways rfc-1009 & rfc-0904 reporter 林揚凱

Requirements for Internet Gateways

RFC-1009

&

RFC-0904

reporter林揚凱

Introduction

Autonomous System

Internet Gateway

Embedded Gateways


Gateways Characteristics

Protocols Required In Gateway

Gateway Algorithms

Operation and Maintenance(O&M)

Packet : A packet is the unit of transmission on a physical network.

Datagram : A datagram is the transmission in the IP protocol.To cross

a particular network a datagram is encapsulated inside a

packet.


Router: A router is a switch that receives data transmission units from input interfaces and,depending on the addresses in those units,routes them to appropriate output interfaces.There can be routers at different levels of protocol.

Gateway :In the Internet documentation generally,a gateway is an IP-Level Router

Datagram 網路層Packet 實體層

Introduction

NETWORK and GATEWAYS


Gateways ： A Gateway is connecting to two or more networks,appearing to each of these networks as a connected host.Thus,is has a physical interface and an IP address on each of the connected network.

GATEWAY

INTERFACE 1IP:X.X.X.X




Network ： Constituent network may be divided into two classed:Local-Area Network(LAN)Wide-Area Network(WAN)

Autonomous Systems(figure 1)


Characteristic ：一、 Be under the control of a single operations and maintenance(Q&M) organization.二、 Employ common routing protocols among themselves,to maintain their routing database dynamically.

Explain ： For technical,managerial,and sometimes political reasons,the gateways of the Internet system are grouped into collections called “autonomous systems”.

Internet Gateway


一、 Conforms to specific Internet protocols specified in this document.二、 Interfaces to two or more packet network.三、 Receives and forwards Internet datagrams.四、 Chooses a next-hop destination for each IP datagram.五、 Supports an interior gateway protocol(IGP) to carry out distributed routing and reachability algorithms with the other gateways in the same autonomous system.六、 Provides system support facilities,including loading,debugging,status reporting.

An Internet gateway is an IP-Level router that perform the following functions:

Embedded Gateways


A gateway may be a stand-alone computer

system , dedicated to its IP router functions .

Alternatively,it is possible to embed gateway

functionality within a host operating system which

supports connections to two or more networks.

Gateways Characteristics


•Advanced routing and forwarding algorithms.

•High availability.

•Advanced O&M(Operation and Maintenance) feature.

•High performance.

•Routing Table

Routing

im1

163.13.200.222

bbs

163.13.200.40

Telnet 163.13.200.40

MIS

163.13.200.32

www

163.13.200.33

163.13.200.254

FDDI 環形網路

Router

Router

Router

163.13.200.40163.13.200.40and

163.13.200.40and

128.0.0.0

163.13.200.40and

163.13.200.0BIOGO

Routing Table

Routing

im1

163.13.200.222

bbs

163.13.200.40

Searching……..

163.13.200.222 0000E8A2IIJJ163.13.200.40163.13.200.254

0000E8A222330000E8A21122

Destination0000E8A22233

Source0000E8A2IIJJ

Src IP Dest IP163.13.200.222 163.13.200.40

DATADATA

FDDI 環形網路

Router

Router163.13.200.254

Telnet 168.95.1.1

168.95.1.1and

168.95.1.1and

0.0.0.0

168.95.1.1

YES

Routing 2

im1

163.13.200.222

bbs

163.13.200.40

Searching……..

163.13.200.222 0000E8A2IIJJ163.13.200.40163.13.200.254

0000E8A222330000E8A21122

Destination0000E8A21122

Source0000E8A2IIJJ

Src IP Dest IP163.13.200.222 163.13.200.254

DATADATA

FDDI 環形網路

Router

Router

163.13.200.254

163.13.254.201

163.13.254.202

Destination Gateway Genmask Iface163.13.254.200 0.0.0.0 255.255.255.252 eth2163.13.200.0 0.0.0.0 255.255.252.0 eth0163.13.204.0 0.0.0.0 255.255.252.0 eth1127.0.0.0 0.0.0.0 255.0.0.0 lo0.0.0.0 163.13.254.201 0.0.0.0 eth2

Routing Table 2

IP:168.95.1.1

eth0 eth1 eth2 eth3

FDDI 環形網路

Router

Router

eth0 :163.13.200.254

eth2:163.13.254.201

eth2:163.13.254.202

FDDI:163.13.192.254

FDDI:163.13.254.1

Protocols Required In Gateway


IP(Internet Protocol)

ICMP(Internet Control Message Protocol)

IGMP(Internet Group Management Protocol)

EGP(Exterior Gateway Protocol)(Figure 1)

IGP(Interior Gateway Protocol)

IGP(Interior Gateway Protocol)(figure 2)


GGP(Gateway-to-Gateway Protocol)

RIP(Routing Information Protocol)

SPF(Shortest-Path-first)

Hello

Routing Information Protocol


RIP 是一個很簡單的 Routing Protocol , 是採用

Distance Vector 的方式 , 所謂 Distance Vector 是指以

Router 的個數來作為距離的判斷 , 而不以實際連

線的速率來作判斷 , 所以在某些時候所選的路徑

是經過最少的 Router , 但是並不一定速度最快 ,

這是使用 RIP 的缺點之一

Gateway Algorithms


Routing Algorithm

Special Addresses and Filters

Redirects

Broadcast and Multicast

TTL(Time-To-Live)

Operation and Maintenance(O&M)


Maintenance--Hardware Diagnosis

Control--Dumping and Rebooting

Control--Configuring the Gateway

Monitoring--Status and Performance

Monitoring--Error Logging


END

requirements for internet gateways rfc-1009 & rfc-0904 reporter 林揚凱

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