Lab 4.9 QoS Pre-classify

Transcription

1 Lab 4.9 QoS Pre-classify Learning Objectives Configure a GRE tunnel Configure QoS pre-classify Verify QoS pre-classify operation Topology Diagram Scenario Weighted fair queuing (WFQ) allows routers to determine the ordering of packets for transmission on the basis of the flow or conversation into which a packet falls. A flow is defined by the source and destination addresses and port numbers, the transport protocol, and the IP Precedence value. Both Generic Routing Encapsulation (GRE) and IPsec tunnels copy a packet s markable type of service/differentiated services (ToS/DiffServ) byte from the inner header to the outer header during encapsulation. Flow-based tools all along the tunnel s path will be able to view the IP Precedence or differentiated 1-8 CCNP: Optimizing Converged Networks v5.0 - Lab 4-9 Copyright 2007, Cisco Systems, Inc

2 services code point (DSCP) marking. However, WFQ manages the allocation of network bandwidth by classifying traffic into prioritized flows, and dividing the network bandwidth fairly between those flows. Along the majority of the tunnel path, the only information able to be used to classify traffic will be the ToS/DiffServ byte. However, at the tunnel endpoints you can make more intelligent decisions about the prioritization of packets because you have access to the inner packets before you encapsulate them with another IP header. This scenario will guide you through implementing the QoS pre-classify feature to ensure that flow-based tools can make more intelligent decisions in provisioning bandwidth for tunneled flows. Preparation This lab uses the Basic Pagent Configuration for TrafGen and the switch to generate and facilitate lab traffic in a stream from TrafGen to R1 to R2. Prior to beginning this lab, configure TrafGen (R4) and the switch according to the Basic Pagent Configuration in Lab 3.1: Preparing for QoS. You can accomplish this easily on R4 by loading the basic-ios.cfg file from flash memory into the NVRAM, and reloading. TrafGen# copy flash:basic-ios.cfg startup-config Destination filename [startup-config]? [OK] 2875 bytes copied in secs (1975 bytes/sec) TrafGen# reload Proceed with reload? [confirm] On the switch, load the basic.cfg file into NVRAM and reload the device. Switch# copy flash:basic.cfg startup-config Destination filename [startup-config]? [OK] 2875 bytes copied in secs (1975 bytes/sec) TrafGen# reload Proceed with reload? [confirm] On TrafGen, instruct TGN to load the basic-tgn.cfg file and to start generating traffic. TrafGen# tgn load-config basic-tgn.cfg TrafGen# tgn start In addition, add the Fast Ethernet 0/5 interface on the switch to VLAN 20 since R3 will be the exit point from the network topology in this lab. Switch# configure terminal Switch(config)# interface fastethernet 0/5 Switch(config-if)# switchport access vlan 20 Switch(config-if)# switchport mode access 2-8 CCNP: Optimizing Converged Networks v5.0 - Lab 4-9 Copyright 2007, Cisco Systems, Inc

3 Step 1: Configure the Physical Interfaces Configure all of the physical interfaces shown in the diagram. Set the clock rate on the serial link between R1 and R2 to , the clock rate of the serial link between R2 and R3 to be , and use the command on all interfaces. Set the informational bandwidth parameter on the serial interfaces. R1(config)# interface fastethernet 0/0 R1(config-if)# ip address R1(config-if)# R1(config-if)# interface serial 0/0/0 R1(config-if)# bandwidth 800 R1(config-if)# ip address R1(config-if)# clock rate R1(config-if)# R2(config)# interface serial 0/0/0 R2(config-if)# bandwidth 800 R2(config-if)# ip address R2(config-if)# R2(config-if)# interface serial 0/0/1 R2(config-if)# bandwidth 128 R2(config-if)# ip address R2(config-if)# clock rate R2(config-if)# R3(config)# interface fastethernet 0/0 R3(config-if)# ip address R3(config-if)# R3(config-if)# interface serial 0/0/1 R3(config-if)# bandwidth 128 R3(config-if)# ip address R3(config-if)# Issue the show interfaces serial 0/0/0 include Queueing command on R1 to verify that the queuing strategy is WFQ. R1# show interface serial0/0/0 include Queueing Queueing strategy: weighted fair If you see fifo as the queuing type, use the interface-level fair-queue command on the serial interface to change the queuing strategy to WFQ. Step 2: Configure Static Routing Configure R1 and R3 with default routes towards R2. R1(config)# ip route R3(config)# ip route To which destination networks will R2 be able to forward IP traffic? 3-8 CCNP: Optimizing Converged Networks v5.0 - Lab 4-9 Copyright 2007, Cisco Systems, Inc

4 Does R2 have any knowledge of how to route to the /16 major network? Step 3: Configure the GRE Tunnel Your company currently maintains a GRE tunnel through the ISP router R2 terminating at R1 and R3. Create the tunnel interfaces on both R1 and R3 and use the addresses in the /16 address range as the endpoints of the tunnel. Use IP addresses in the /24 subnet as the addressing for the tunnel interfaces themselves. R2 does not need to have routing information for the network addresses you use in your private network ( /16). Create a GRE tunnel interface, by issuing the interface tunnel number command to enter interface configuration mode for the tunnel interface. The tunnel interface number is only locally significant; however, for simplicity, use tunnel interface number 0 on both R1 and R3. Next, configure addressing for the tunnel interface itself with the ip address address mask command, just like you would do on any other interface. Finally, assign a source and destination address for the tunnel with the tunnel source address and tunnel destination address commands, respectively. The tunnel source can alternatively be specified by interface. Tunneled traffic will be first sent to the other end of the GRE tunnel before being forwarded to its destination. Tunneling accomplishes this function by encapsulating packets with an outer IP header with the source and destination addresses supplied with the two previous commands. You do not need to configure a tunnel mode because the default tunnel mode is GRE. For more information on configuring GRE tunnels, reference the ISCW Lab 3.2: Configuring GRE Tunnels. R1(config)# interface tunnel 0 R1(config-if)# tunnel source serial 0/0/0 R1(config-if)# tunnel destination R1(config-if)# ip address R3(config)# interface tunnel 0 R3(config-if)# tunnel source serial 0/0/1 R3(config-if)# tunnel destination R3(config-if)# ip address Verify that you can ping across the tunnel to the other side. If you can do this, you have successfully set up the tunnel. R1# ping CCNP: Optimizing Converged Networks v5.0 - Lab 4-9 Copyright 2007, Cisco Systems, Inc

5 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to , timeout is 2 seconds: Success rate is 100 percent (5/5), round-trip min/avg/max = 20/28/44 ms R3# ping Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to , timeout is 2 seconds: Success rate is 100 percent (5/5), round-trip min/avg/max = 12/24/36 ms Step 4: Configure Routing Configure routing between R1 and R3 using Enhanced Interior Gateway Routing Protocol (EIGRP). Include the entire /16 major network in AS 1 and disable automatic summarization. R1(config)# router eigrp 1 R1(config-router)# no auto-summary R1(config-router)# network R3(config)# router eigrp 1 R3(config-router)# no auto-summary R3(config-router)# network Verify that the number of packets counted is increasing on the outbound interface of R3 using the show interfaces fastethernet 0/1 command. Issue the command twice to make sure the number of packets output has changed. If the number is not increasing, troubleshoot Layer 1, 2, and 3 connectivity and the EIGRP topology. If a tunnel s queuing strategy is first-in, first-out (FIFO), you may experience extreme delays in sending EIGRP packets over your tunnel. Remember that all of the traffic generated by Pagent is attempting to traverse the link as well and may cause delays in sending the EIGRP hellos. Step 5: Enable the QoS Pre-classify Feature On R1, issue the show queue interface command to view the open conversations exiting the Serial 0/0/0 interface. R1 show queue serial 0/0/0 Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: Queueing strategy: weighted fair Output queue: 64/1000/64/ (size/max total/threshold/drops) Conversations 1/10/256 (active/max active/max total) Reserved Conversations 0/0 (allocated/max allocated) Available Bandwidth 1158 kilobits/sec (depth/weight/total drops/no-buffer drops/interleaves) 64/32384/ /0/0 Conversation 38, linktype: ip, length: 991 source: , destination: , id: 0x45C8, ttl: 255, prot: CCNP: Optimizing Converged Networks v5.0 - Lab 4-9 Copyright 2007, Cisco Systems, Inc

6 Notice there is only one conversation. The protocol number at the end is 47, which is GRE the default tunnel encapsulation. Why is there only one conversation listed, despite multiple traffic flows coming out of TrafGen? Does GRE copy the inner IP header s ToS/DiffServ byte to the encapsulating IP header? On the basis of your answer to the previous question and given the current configuration of the network, what is the maximum number of tunneled GRE conversations that could be seen in the output of the show queue serial 0/0/0 command? QoS pre-classify allows traffic to be classified by the physical interface s flowbased queuing strategy before being encapsulated so that the physical interface s network bandwidth can be fairly distributed amongst distinct tunneled flows, and not only those tunneled flows that will be based on IP Precedence. This ensures that a disproportionate amount of tunneled traffic is not dropped or significantly delayed at the physical interface. Enable the QoS pre-classify feature by issuing the qos pre-classify command in interface configuration mode for the tunnel interfaces. R1(config)# interface tunnel 0 R1(config-if)# qos pre-classify R3(config)# interface tunnel 0 R3(config-if)# qos pre-classify Now, try looking at the queue contents of the serial interface. R1# show queue serial0/0/0 6-8 CCNP: Optimizing Converged Networks v5.0 - Lab 4-9 Copyright 2007, Cisco Systems, Inc

7 Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: Queueing strategy: weighted fair Output queue: 69/1000/64/ (size/max total/threshold/drops) Conversations 7/11/256 (active/max active/max total) Reserved Conversations 0/0 (allocated/max allocated) Available Bandwidth 1158 kilobits/sec (depth/weight/total drops/no-buffer drops/interleaves) 12/32384/437229/0/0 Conversation 43, linktype: ip, length: 641 TOS: 0 prot: 6, source port 0, destination port 6000 (depth/weight/total drops/no-buffer drops/interleaves) 6/32384/436558/0/0 Conversation 189, linktype: ip, length: 129 TOS: 0 prot: 6, source port 0, destination port 25 (depth/weight/total drops/no-buffer drops/interleaves) 8/32384/436129/0/0 Conversation 244, linktype: ip, length: 158 TOS: 0 prot: 6, source port 0, destination port 80 (depth/weight/total drops/no-buffer drops/interleaves) 7/32384/437819/0/0 Conversation 31, linktype: ip, length: 899 TOS: 0 prot: 6, source port 0, destination port 123 (depth/weight/total drops/no-buffer drops/interleaves) 8/32384/441933/0/0 Conversation 187, linktype: ip, length: 606 TOS: 0 prot: 6, source port 0, destination port 23 (depth/weight/total drops/no-buffer drops/interleaves) 11/32384/445293/0/0 Conversation 18, linktype: ip, length: 1003 TOS: 0 prot: 6, source port 0, destination port 110 (depth/weight/total drops/no-buffer drops/interleaves) 17/32384/3157/0/0 Conversation 164, linktype: ip, length: 1504 TOS: 0 prot: 6, source port 0, destination port 6000 What is different about this output compared to the show interfaces serial 0/0/0 output shown at the beginning of Step 5? Final Configurations R1# show run hostname R1 interface Tunnel0 ip address CCNP: Optimizing Converged Networks v5.0 - Lab 4-9 Copyright 2007, Cisco Systems, Inc

8 qos pre-classify tunnel source Serial0/0/0 tunnel destination interface FastEthernet0/0 ip address interface Serial0/0/0 ip address fair-queue clock rate router eigrp 1 network no auto-summary ip route end R2# show run hostname R2 interface Serial0/0/0 ip address fair-queue interface Serial0/0/1 ip address clock rate end R3# show run hostname R3 interface Tunnel0 ip address qos pre-classify tunnel source Serial0/0/1 tunnel destination interface FastEthernet0/1 ip address interface Serial0/0/1 ip address router eigrp 1 network no auto-summary ip route end 8-8 CCNP: Optimizing Converged Networks v5.0 - Lab 4-9 Copyright 2007, Cisco Systems, Inc