Giao thức định tuyến - Chapter 7 pdf

RIPv2 Routing Protocols and Concepts – Chapter 7 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public ITE PC v4.0 Chapter 1 1 Objectives  En cou nt e r a n d desc ri be th e limit a ti o n s o f RIPv1’ s cou e a d desc be e a o s o s limitations.  Apply the basic Routing Information Protocol Version Apply the basic Routing Information Protocol Version 2 (RIPv2) configuration commands and evaluate RIPv2 classless routing updates.  Analyze router output to see RIPv2 support for VLSM and CIDR  Identify RIPv2 verification commands and common RIPv2 issues.  Configure, verify, and troubleshoot RIPv2 in “hands- on” labs ITE PC v4.0 Chapter 1 2 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public Introduction Introduction  Difference between RIPv1 & RIPv2  RIPv1  RIPv1 •A classful distance vector routing protocol • Does not support discontiguous subnets Does not support discontiguous subnets •Does not support VLSM •Does not send subnet mask in routing update •Routing updates are broadcast RIPv2 •A classless distance vector routing protocol that is an enhancement of RIPv1 ’ s features enhancement of RIPv1 s features . •Next hop address is included in updates •Routing updates are multicast (224.0.0.9 vs. 255.255.255.255) http://www.cisco.com/univercd/cc/t d/doc/cisintwk/ito_doc/rip.htm ITE PC v4.0 Chapter 1 3 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public •The use of authentication is an option Introduction  Similarities between RIPv1 & RIPv2 – Use of timers to prevent routing loops Use of timers to prevent routing loops – Use of split horizon or split horizon with poison reverse to also help prevent routing loops. – Use of triggered updates when there is a change in the topology for faster convergence. Maximum hop count of 15 with the hop count of 16 signifying – Maximum hop count of 15 , with the hop count of 16 signifying an unreachable network. ITE PC v4.0 Chapter 1 4 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public RIP 1 Li it ti RIP v 1 Li m it a ti ons  Lab Topology 3t t  3 rou t er se t up Topology is discontiguous There exists a static summary route Static route information can be injected into routing table updates using redistribution.  Routers 1 & 3 contain VLSM Routers 1 & 3 contain VLSM networks Remember that both the R1 and R3 routers have subnets that are part of the 172 30 0 0/16 major classful the 172 . 30 . 0 . 0/16 major classful network (class B). Also remember that R1 and R3 are connected to R2 usin g subnets of the g 209.165.200.0/24 major classful network (class C). This topology is discontiguous and will not converge because ITE PC v4.0 Chapter 1 5 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public will not converge because 172.30.0.0/16 is divided by the 209.165.200.0/24. RIP 1 Li it ti RIP v 1 Li m it a ti ons  The topology shows that R2 has a static R2 has a static summary route to the 192.168.0.0/16 network. The configuration of this summar y route will be ITE PC v4.0 Chapter 1 6 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public y displayed later in this section. RIP 1 Li it ti RIP v 1 Li m it a ti ons  Review the VLSM addressing scheme in the figure As shown scheme in the figure . As shown in the top chart, both R1 and R3 have had the 172.30.0.0/16 network subnetted into /24 subnets subnets . –Four of these /24 subnets are assigned: – two to R1 ( 172.30.1.0/24 and ( 172.30.2.0/24) –two to R3 (172.30.100.0/24 and 172.30.110.0/24). Ithbtt ht h  I n th e b o tt om c h ar t , we h ave taken the 172.30.200.0/24 subnet and subnetted it again, usin g the first four bits for g subnets and the last four bits for hosts. The result is a 255.255.255.240 mask or /28. Subnet 1 and Subnet 2 are ITE PC v4.0 Chapter 1 7 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public Subnet 1 and Subnet 2 are assigned to R3. RIP 1 Limitations RIP v 1 Limitations  Scenario Continued S  VL S M -Recall this is sub netting the subnet  Private IP addresses are on LAN links  Public IP addresses are used on WAN links (through an ISP, or when inside users dt t id it nee d t o access ou t s id e s it es, a public IP address must be used.)  Loopback interfaces -These are virtual interfaces that can be pinged and ITE PC v4.0 Chapter 1 8 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public that can be pinged and added to routing table Cisco has set these addresses aside for educational purposes. RIPv1 Limitations  Loopback interfaces Notice that R3 is using loopback interfaces (Lo0, Lo1, and Lo2). A loopback interface is a software-only interface that is used to emulate a physical interface is used to emulate a physical interface . Like other interfaces, it can be assigned an IP address. Loopback interfaces are also used by other routing p rotocols , such as OSPF , for different p ur p oses. p, , pp These uses will be discussed in Chapter 11 OSPF. In a lab environment, loopback interfaces are useful in creating additional networks without having to add more physical interfaces on the router more physical interfaces on the router . A loopback interface can be pinged and the subnet can be advertised in routing updates.  Therefore, loopback interfaces are ideal for Therefore, loopback interfaces are ideal for simulating multiple networks attached to the same router. In our example, R3 does not need four LAN interfaces to demonstrate multiple subnets and ITE PC v4.0 Chapter 1 9 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public interfaces to demonstrate multiple subnets and VLSM. Instead, we use loopback interfaces. RIPv1 Limitations RIPv1 Limitations  Route redistribution Redistribution involves taking the routes from one routing – Redistribution involves taking the routes from one routing source and sending those routes to another routing source. • In our example topology, we want the RIP process on R2 to redistribute our static route (192.168.0.0/16) by importing the route into RIP and then sending it to R1 and R3 using the RIP process. R2( fi t)#ditibt tti - R2( con fi g-rou t er )# re di s t r ib u t e s t a ti c ITE PC v4.0 Chapter 1 10 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public [...]... v4.0 Chapter 1 © 20 07 Cisco Systems, Inc All rights reserved Cisco Public 32 Verifying T V if i & Troubleshooting RIPv2 bl h ti RIP 2 Reasons why it’s good to authenticate routing information y g g -Prevent the possibility of accepting invalid routing updates -Contents of routing updates are encrypted g p yp Types of routing protocols that can use authentication -RIPv2 RIPv2 -EIGRP -OSPF OSPF -IS-IS -BGP... v4.0 Chapter 1 © 20 07 Cisco Systems, Inc All rights reserved Cisco Public 29 VLSM & CIDR To verify that supernets are being sent and received use the following commands -Show ip route -Debug ip rip Debug ITE PC v4.0 Chapter 1 © 20 07 Cisco Systems, Inc All rights reserved Cisco Public 30 Verifying & Troubleshooting RIPv2 Basic Troubleshooting steps -Check the status of all links Check -Check cabling -Check... interface – Since the interface is 172 .30.100.1 with a /24 mask, it will only i l d ith k ill l include 172 .30.0.0 subnets with a /24 mask The only one that meets this condition is 172 .30.110.0 – The other 172 .30.0.0 subnets, 172 .30.200.16/28 and 172 .30.200.32/28, are not included because the /28 masks do not match the /24 mask of the outgoing interface ITE PC v4.0 Chapter 1 © 20 07 Cisco Systems, Inc All rights... R3 router is configured with VLSM subnets, subnets all of which are members of the class B network 172 .30.0.0/16: – 172 .30.100.0/24 (FastEthernet 0/0) 172 .30.100.0/24 – 172 .30.110.0/24 (Loopback 0) – 172 .30.200.16/28 (Loopback 1) – 172 .30.200.32/28 (L 172 30 200 32/28 (Loopback 2) b k As we saw with the 172 .30.0.0/16 updates to R2 by R3, p y –RIPv1 either summarizes the subnets to the classful boundary... which subnets to advertise ITE PC v4.0 Chapter 1 © 20 07 Cisco Systems, Inc All rights reserved Cisco Public 17 RIPv1 Limitations Why is RIPv1 on R3 not including the other subnets, 172 .30.200.16/28 172 30 200 16/28 and 172 .30.200.32/28, in updates to R4? – Those subnets do not have the same subnet mask as FastEthernet 0/0 – R3 will only include those 172 .30.0.0 172 30 0 0 routes in its routing table... its own 172 30 0 0 routes: 172 .30.0.0 172 .30.2.0/24 and 172 .30.1.0/24 •But R1 does not send R2 those subnets •R3 has a similar routing table •Both R1 and R3 are b B th d boundary routers and d t d are only sending the summarized 172 .30.0.0 network to R2 in their RIPv1 routing updates •As a result, R2 only k A lt l knows about th b t the 172 .30.0.0/16 classful network and is unaware of any 172 .30.0.0... R1 and R3 routers will summarize their 172 .30.0.0 subnets to the classful major network address of 172 30 0 0 when sending 172 .30.0.0 routing updates to R2 –From the perspective of R2, both updates have an equal cost of 1 hop to reach network 172 30 0 0/16 As you will see R2 installs both paths in the 172 .30.0.0/16 see, routing table ITE PC v4.0 Chapter 1 © 20 07 Cisco Systems, Inc All rights reserved... the RIPv2 fields in the route entry RIPv1 ITE PC v4.0 Chapter 1 RIPv2 © 20 07 Cisco Systems, Inc All rights reserved Cisco Public 21 Configuring RIPv2 Configuring RIPv2 on a Cisco router -Requires using the version 2 command -RIPv2 ignores RIPv1 RIPv2 updates To verify RIPv2 is configured use the show ip protocols command ITE PC v4.0 Chapter 1 © 20 07 Cisco Systems, Inc All rights reserved Cisco Public... Yes I can take version 1 or 2 ITE PC v4.0 Chapter 1 No No I can not take version 1 I can only send version 2 © 20 07 Cisco Systems, Inc All rights reserved Cisco Public 23 POP Quiz How do you make the RIPv2 back to the default “send 1” and receive 1 or 2”? - Hint: Gad(config-router)#version 1 is not the answer Version 2 Version 1 ITE PC v4.0 Chapter 1 © 20 07 Cisco Systems, Inc All rights reserved Cisco... Examining the routing tables -To examine the contents of routing updates use the debug ip rip command R2 is receiving two 172 .30.0.0 equal cost i i i t 172 30 0 0 l t routes with a metric of 1 hop R2 is receiving one route on Serial 0/0/0 from R1 and the other route on Serial 0/0/1 from R3 ITE PC v4.0 Chapter 1 R2 has two equal cost routes to the 172 .30.0.0/16 network © 20 07 Cisco Systems, Inc All rights . network 172 .30.0.0/16: – 172 .30.100.0/24 (FastEthernet 0/0) 172 .30.100.0/24 (FastEthernet 0/0) – 172 .30.110.0/24 (Loopback 0) – 172 .30.200.16/28 (Loopback 1) 172 30 200 32/28 (L b k 2) – 172 . 30 . 200 . 32/28 . 172 .30.0.0/16 network subnetted into /24 subnets subnets . –Four of these /24 subnets are assigned: – two to R1 ( 172 .30.1.0/24 and ( 172 .30.2.0/24) –two to R3 ( 172 .30.100.0/24 and 172 .30.110.0/24) on l y i nc l u d e 172 .30.0.0 subnets with a /24 mask. The only one that meets this condition is 172 .30.110.0. – The other 172 .30.0.0 subnets, 172 .30.200.16/28 and 172 .30.200.32/28, are