Static Routing

1. Static Routing Routing Protocols and Concepts – Chapter 2

2. Objectives • Define the general role a router plays in networks. • Describe the directly connected networks, different router interfaces • Examine directly connected networks in the routing table and use the CDP protocol • Describe static routes with exit interfaces • Describe summary and default route • Examine how packets get forwarded when using static routes • Identify how to manage and troubleshoot static routes

3. Context Index • 2.1 Router and Network • 2.2 Router Configuration Review • 2.3 Exploring Directly Connected Networks • 2.4 Static Route with “Next Hop” Address • 2.5 Static Routes with Exit Interfaces • 2.6 Summary and Default Static Routes • 2.7 Managing and Troubleshooting Static Routes • 2.8 Static Route Configuration Labs

4. 2.1 Router and Network 路由器和网络

5. 2.1.1 Role of the Router • Functions of a Router • Best Path Selections • Forwarding packets to destination

6. 2.1.2 Introducing the Topology • Introducing the Topology • 3 routers connected via WAN links • Each router connected to a LAN represented by a switch and a PC

7. 2.1.3 Examining the connection of the Router • Connections of a Router for WAN • -A router has a DB-60 port that can support 5 different cabling standards • Connections of a Router for Ethernet • -2 types of connectors can be used: Straight through and Cross-over • Straight through used to connect: • -Switch-to-Router, Switch-to-PC, Hub-to-PC, Hub-to-Server • Cross-over used to connect: • -Switch-to-Switch, PC-to-PC, Switch-to-Hub, Hub-to-Hub, Router-to-Router , Router-to-Server

8. 2.1.3 Examining the connection of the Router

9. 2.2 Router Configuration Review 路由器配置回顾

10. 2.2.1 Examining Router Interfaces • Examining Router Interfaces • -Show ip route command – used to view routing table • -Show Interfaces command – used to show status of an interface • -Show ip Interface brief command – used to show a portion of the interface information • -Show running-config command – used to show configuration file in RAM

11. 2.2.1 Examining Router Interfaces 出厂配置时的显示：默认情况下，所有路由器接口都是 shutdown 状态（即已关闭）

12. 2.2.2 Configuring an Ethernet Interface • Unsolicited Messages from IOS

13. 2.2.2 Configuring an Ethernet Interface • Reading the Routing Table

14. 2.2.3 Verifying Ethernet interface

15. 2.2.3 Verifying Ethernet interface • Ethernet interfaces participate in ARP

16. 2.2.4 Configuring a Serial Interface • Configuring a Serial interface • -Enter interface configuration mode • -Enter in the ip address and subnet mask • -Enter in the no shutdown command • Example: • R1(config)# interface serial 0/0/0 • R1(config-if)# ip address 172.16.2.1 255.255.255.0 • R1(config-if)# no shutdown

17. Physically connecting a WAN Interface • A WAN Physical Layer connection has sides: • Data Circuit-terminating Equipment (DCE) – This is the service provider. CSU/DSU is a DCE device. • Data Terminal Equipment (DTE) – Typically the router is the DTE device.

18. 2.2.5 Examining Router Interfaces • Configuring serial links in a lab environment • One side of a serial connection must be considered a DCE • This requires placing a clocking signal – use the clock rate command. • Example: • R1(config)# interface serial 0/0/0 • R1(config-if)# clockrate64000

19. 2.2.5 Examining Router Interfaces

20. 2.3 Exploring Directly Connected Networks 探究直连路由

21. 2.3.1 Verifying Changes the Routing Table • Routing Table Concepts • show ip routecommand reveals the content of the routing table. Why only have one Connected Route?

22. 2.3.1 Verifying Changes the Routing Table • Observing Routes as They are Added to the Routing Table.

23. 2.3.1 Verifying Changes the Routing Table • Remove a Connected Route from Routing Table • Disable debug ip routing by using either the undebug ip routingcommand or the undebug allcommand.

24. 2.3.2 Devices on Directly Connected Networks • When a router only has its interfaces configured & no other routing protocols are configured then: • -The routing table contains only the directly connected networks • -Onlydevices on the directly connected networks are reachable

25. 2.3.2 Devices on Directly Connected Networks

26. 2.3.2 Devices on Directly Connected Networks • Pings are discarded

27. 2.3.3 Cisco Discovery Protocol (CDP) • Purpose of CDP • A layer 2 Cisco proprietary tool used to gather information about other directly connected Cisco devices. • Concept of neighbors • 2 types of neighbors • Layer 3 neighbors • Layer 2 neighbors (CDP operates at Layer 2 only)

28. 2.3.3 Cisco Discovery Protocol (CDP) • CDP Operation (间隔60s，失效时间180s) • CDP show commands • Show cdp neighbors • Displays the following information: • Neighbor device ID • Local interface • Holdtime value, in seconds • Neighbor device capability code • Neighbor hardware platform • Neighbor remote port ID • Show cdp neighbors detail • -Useful in determining if an IP address configuration error

29. 2.3.4 Using CDP for Network Discovery

30. 2.4 Static Route with “Next Hop” Address 带下一跳地址的静态路由

31. 2.4.1 Purpose and Command Syntax of ip route • Purpose of ip route • A manually configured route used when routing from a network to a stub network

32. 2.4.1 Purpose and Command Syntax of ip route • IP route command • To configure a static route use the following command: ip route • Example:

33. 2.4.2 Configuring Static Route • Installing a Static Route in the Routing Table

34. 2.4.2 Configuring Static Route • Configuring routes to 2 or more remote networks • R1(config)# ip route 192.168.1.0 255.255.255.0 172.16.2.2 • R1(config)# ip route 192.168.2.0 255.255.255.0 172.16.2.2

35. 2.4.3 Routing Table Principles and Static route • 3 Routing principles • Ping测试： • PC1 to 172.16.2.1 • PC1 to 172.16.2.2 • PC1 to PC2 • PC3 to PC2

36. 2.4.3 Routing Table Principles and Static route • Finish the configuration

37. 2.4.4 Recursive Route Lookup • Resolving to an Exit Interface • The router first must match static route’s destination IP address with the Next hop address • The next hop address is then matched to an exit interface

38. 2.4.4 Recursive Route Lookup

39. 2.4.4 Recursive Route Lookup • Exit Interface is Down

40. 2.5 Static Routes with Exit Interfaces 带送出接口的静态路由

41. 2.5.1 Static Route and an Exit Interface • Configuring a Static route with an Exit Interface (本路由器接口) • single search instead of 2 searches. • serial point-to-point networks.

42. 2.5.2 Modifying Static routes • Modifying Static routes • Existing static routes cannot be modified. The old static route must be deleted by placing no in front of the ip route • Example: no ip route 192.168.2.0 255.255.255.0 172.16.2.2 • A new static route must be rewritten in the configuration

43. 2.5.3 Verifying the Static Route Configuration Try it

44. 2.5.4 Static routes and Ethernet exit interfaces • 需要进行ARP解析 • 下一跳表示为接口时可能会出现问题

45. 2.6 Summary and Default Static Routes 总结和默认静态路由

46. 2.6.1 Summary Static Route • Summarizing routes reduces the size of the routing table. • Route summarization is the process of combining a number of static routes into a single static route.

47. 2.6.1 Summary Static Route • Configuring a summary static route • Step 1: Delete the current static route • Step 2: Configure the summary static route • Step 3: Verify the new static route

48. 2.6.2 Default Static Route • Default Static Route • This is a route that will match all packets. • Stub routers that have a number of static routes all exiting the same interface are good candidates for a default route. • Configuring a default static route • Example: • Router(config)# ip route 0.0.0.0 0.0.0.0 [exit-interface | ip-address ]

49. 2.6.2 Default Static Route • Default static routes and subnet masks • Since the subnet mask used on a default static route is 0.0.0.0 all packets will match. R1(config)# ip route 0.0.0.0 0.0.0.0 serial 0/0/0

50. Verifying a Default Static Route • Before