Requirements for Internet Gateways

1. Requirements for Internet Gateways RFC-1009 & RFC-0904 reporter 林揚凱

2. Requirements for Internet Gateways • Gateways Characteristics • Protocols Required In Gateway • Gateway Algorithms • Operation and Maintenance(O&M) • Introduction • Autonomous System • Internet Gateway • Embedded Gateways

3. Requirements for Internet Gateways Introduction • 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. Datagram 網路層 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 Packet 實體層

4. Requirements for Internet Gateways NETWORK and GATEWAYS Network：Constituent network may be divided into two classed: Local-Area Network(LAN) Wide-Area Network(WAN) 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.

5. Requirements for Internet Gateways Autonomous Systems(figure 1) Explain：For technical,managerial,and sometimes political reasons,the gateways of the Internet system are grouped into collections called “autonomous systems”. 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.

6. Requirements for Internet Gateways Internet Gateway An Internet gateway is an IP-Level router that perform the following functions: 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.

7. Requirements for Internet Gateways 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.

8. Requirements for Internet Gateways Gateways Characteristics • Advanced routing and forwarding algorithms. • High availability. • Advanced O&M(Operation and Maintenance) feature. • High performance. • Routing Table

9. 163.13.200.222 163.13.200.40 Router im1 bbs MIS www Router FDDI環形網路 163.13.200.32 163.13.200.33 Telnet163.13.200.40 Routing 163.13.200.254

10. 163.13.200.40 163.13.200.40 163.13.200.40 and and and Routing Table BIOGO 163.13.200.0 Router 128.0.0.0 163.13.200.40

11. 163.13.200.222 0000E8A2IIJJ 163.13.200.40 0000E8A22233 163.13.200.254 0000E8A21122 163.13.200.222 163.13.200.40 Router bbs im1 Router FDDI環形網路 Telnet 168.95.1.1 Destination 0000E8A22233 Source 0000E8A2IIJJ Src IP Dest IP 163.13.200.222 163.13.200.40 DATA Searching…….. Routing 163.13.200.254

12. 168.95.1.1 168.95.1.1 and and 0.0.0.0 YES 168.95.1.1

13. 163.13.200.222 0000E8A2IIJJ 163.13.200.40 0000E8A22233 163.13.200.254 0000E8A21122 163.13.200.40 163.13.200.222 Router bbs im1 Router FDDI環形網路 Destination 0000E8A21122 Source 0000E8A2IIJJ Src IP Dest IP 163.13.200.222 163.13.200.254 DATA Searching…….. Routing 2 163.13.254.201 163.13.254.202 163.13.200.254

14. eth0 eth1 eth2 eth3 Routing Table 2 IP:168.95.1.1 Destination Gateway Genmask Iface 163.13.254.200 0.0.0.0 255.255.255.252 eth2 163.13.200.0 0.0.0.0 255.255.252.0 eth0 163.13.204.0 0.0.0.0 255.255.252.0 eth1 127.0.0.0 0.0.0.0 255.0.0.0 lo 0.0.0.0 163.13.254.201 0.0.0.0 eth2

15. Router Router FDDI環形網路 FDDI:163.13.192.254 eth2:163.13.254.201 FDDI:163.13.254.1 eth2:163.13.254.202 eth0 :163.13.200.254

16. Requirements for Internet Gateways 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)

17. Requirements for Internet Gateways IGP(Interior Gateway Protocol)(figure 2) GGP(Gateway-to-Gateway Protocol) RIP(Routing Information Protocol) SPF(Shortest-Path-first) Hello

18. Requirements for Internet Gateways 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

19. Requirements for Internet Gateways Gateway Algorithms Routing Algorithm Special Addresses and Filters Redirects Broadcast and Multicast TTL(Time-To-Live)

20. Requirements for Internet Gateways Operation and Maintenance(O&M) Maintenance--Hardware Diagnosis Control--Dumping and Rebooting Control--Configuring the Gateway Monitoring--Status and Performance Monitoring--Error Logging

21. Requirements for Internet Gateways END