iprouting(ppt53)-經(jīng)營(yíng)管理(參考版)
2024-08-20 15:12本頁(yè)面
【正文】 來(lái)自 中國(guó)最大的資料庫(kù)下載 IP Routing 來(lái)自 中國(guó)最大的資料庫(kù)下載 Overview What is Routing? The Routing Process IP Routing Distance Vector Routing Protocols Link State Routing Protocols Routing Information Protocol (RIP) Interior Gateway Routing Protocol (IGRP) Verifying the IP Routing Configuration 來(lái)自 中國(guó)最大的資料庫(kù)下載 What is Routing (1)? 來(lái)自 中國(guó)最大的資料庫(kù)下載 What is Routing (2)? ? To be able to route packets, a router must know, at a minimum, the following: ? Destination address ? Remote works from neighbor routers or administrator ? Possible routers to all remote works ? The best route to each remote work ? How to maintain and verify routing information ? Static Routing ? Dynamic Routing 來(lái)自 中國(guó)最大的資料庫(kù)下載 What is Routing (3)? ? LANtoLAN Routing ? Routers must be capable of seamlessly handling packets encapsulated into different lowerlevel frames without changing the packets’ Layer 3 addressing. ? LANtoWAN Routing ? The routers enable LANtoWAN packet flow by keeping the endtoend source and destination addresses constant while encapsulating the packet at the port to a data link that is appropriate for the next hop along the path 來(lái)自 中國(guó)最大的資料庫(kù)下載 The Routing Process IP Address = Hardware Address = 08004. . . IP Address = Hardware Address = 08009. . . ARP Cache 08009. . . 08006. . . ARP Cache 08004. . . 4 1 08005... 08006... 2 ping ARP Cache Network 1 Network 2 4 3 ARP Broadcast for Router Interface A ARP Broadcast for Router Interface B A Router B E0 E1 14 1 1 1 2 1 6 1 7 3 8 3 9 Routing Table 3 10 3 11 3 12 3 13 4 14 來(lái)自 中國(guó)最大的資料庫(kù)下載 IP Routing Example in the Book Static Routing Default Routing Dynamic Routing Administrative Distances Routing Protocols Comparison between Distance Vector and Link State Routing 來(lái)自 中國(guó)最大的資料庫(kù)下載 Example in the Book S0 S1 2501B E0 E0 S0 2501A S0 E0 2501C S0 F0/0 2612A Set the clock rate to this interface 來(lái)自 中國(guó)最大的資料庫(kù)下載 Static Routing (1) ? The process of an administrator manually adding routes in each router’s routing table ? Advantages: ? No overhead on the router CPU ? No bandwidth usage between routers ? Security (administrator can allows routing to certain works) ? Disadvantages: ? Knowledge about the interwork is required ? Manually updating the routing table whenever changes ? Not efficient and feasible in large owrks 來(lái)自 中國(guó)最大的資料庫(kù)下載 Static Routing (2) ? Command used to add a static route to a routing table: ip route mask next_hop_address or exit_interface [permanent] ? [permanent] is used to keep the route in the routing table even if the next hop device cannot be contacted. ? Command used to delete a static route to a routing table: no ip route work mask next_hop_address or exit_interface 來(lái)自 中國(guó)最大的資料庫(kù)下載 Default Routing ? Default route – a static routing table entry (the gateway of last resort) used to direct frames whose next hop is not specified in the routing table ? It is used on stub works, which means that they have only one exit port out of the work. It also acts as the gateway for this router. ? Use ip route next_hop_address to define Default route ? Always use together with ip classless to tell a router to forward packets to a default route when the destination work is not in the routing table. ? Ip classless mand is on by default for IOS 來(lái)自 中國(guó)最大的資料庫(kù)下載 Dynamic Routing ? The process of using routing protocols to find and update routing tables on routers. ? Advantages: ? Automatically adjust for changes in the interwork ? Dynamic routing can be fault tolerant and can scale well ? Disadvantage: ? Overhead on the router CPU ? Bandwidth usage between routers ? Examples: RIP, IGRP (covered in CCNA 2) ? Interior Gateway Protocol (IGP) – exchange routing information with routers in the same autonomous system (AS) ? Exterior Gateway Protocol (EGP) – munication between ASs. ? AS – a collection of works under a mon administrative domain. 來(lái)自 中國(guó)最大的資料庫(kù)下載 Administrative Distances ? To rate the trustworthiness of routing information received on a router from a neighbor router. ? Value 0255: the smaller the most trusted, and if several routes to same destination present, the router will use the route with smaller administrative distances instead Route Source Default Distance Connected interface (work directly connected) 0 Static route 1 EIGRP (enhanced IGRP) 90 IGRP 100 OSPF
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