Requirements for Internet Gateways RFC-1009 & RFC-0904 reporter 林林林
Introduction
Autonomous System
Internet Gateway
Embedded Gateways
Requirements for Internet 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.
Requirements for Internet Gateways
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
Requirements for Internet 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
INTERFACE 2IP:X.X.X.X
INTERFACE 3IP:X.X.X.X
INTERFACE 4IP: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)
Requirements for Internet Gateways
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
Requirements for Internet Gateways
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
Requirements for Internet 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
Requirements for Internet Gateways
•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
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
Requirements for Internet Gateways
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)
Requirements for Internet Gateways
GGP(Gateway-to-Gateway Protocol)
RIP(Routing Information Protocol)
SPF(Shortest-Path-first)
Hello
Routing Information Protocol
Requirements for Internet Gateways
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
Requirements for Internet Gateways
Routing Algorithm
Special Addresses and Filters
Redirects
Broadcast and Multicast
TTL(Time-To-Live)
Operation and Maintenance(O&M)
Requirements for Internet Gateways
Maintenance--Hardware Diagnosis
Control--Dumping and Rebooting
Control--Configuring the Gateway
Monitoring--Status and Performance
Monitoring--Error Logging