Section 8: QoS (5 Points)

• Configure a QoS policy on R2 for traffic flowing from VLAN1 toward the rest of your network. Traffic found to have an IP precedence of 7, 5, and 1 should be limited to a maximum of 2 Mbps. Traffic above this figure with the stated precedence should be discarded. Use only one ACL to accomplish this requirement. Assume normal and excess burst sizes to both be 40000.

You are required to configure rate limiting inbound on R2 FastEthernet0/0. As you can only use one ACL to match on the precedence value, you must use a precedence mask. To match on precedence values, you must first convert these values in an 8-bit format where 00000001 is for precedence 0, 00000010 is for precedence 1, 00000100 for 2, 00001000 for 3, 00010000 for 4, 00100000 for 5, 01000000 for 6, and 10000000 for 7. 10100010 matches precedence values 7, 5, and 1 as the mask is an add operation of the individual values. This value is then converted into Hex giving the mask value of A2, which is used in the access-list. If you have configured this correctly as shown in Example 3-84, you have scored 2 points.

Example 3-84. R2 Rate Limiting Configuration

 interface FastEthernet0/0  rate-limit input access-group rate-limit 20 2000000 40000 40000    conform-action transmit exceed-action drop ! access-list rate-limit 20 mask A2 

• A future FXS module will be installed into R6 and VoIP traffic will flow between R1 and R6. Configure RSVP on R1 so that the RSVP setup must be complete before the destination phone rings. Each RSVP flow should be set to 100 kbps and allow for a maximum of 2 flows; allow a maximum of 15 seconds for this setup. You should also allow for 64 discard messages and 64 dynamic queues in your QoS configuration. You are not required to perform any configuration on R6 but can assume that the phone number on R6 will be 01962 when configuring the dial plan on R1.

A vast amount of information is supplied to you within this question; you just need to make sense of it all and put it into a valid configuration. Your flows are to be 100 kbps with a maximum of two flows, so your RSVP statement will be ip rsvp bandwidth 200 100. Fifteen seconds for this setup is enabled by the command call rsvp-sync resv-timer 15 and your fair-queue configuration should include the 64 discard messages, 64 dynamic queues, and, finally, the 2 RSVP flows using the command fair-queue 64 64 2. If you have configured this correctly as shown in Example 3-85, you have scored 3 points.

Example 3-85. R1 RSVP Voice QoS Configuration

 call rsvp-sync call rsvp-sync resv-timer 15 ! interface FastEthernet0/0 fair-queue 64 64 2 ip rsvp bandwidth 200 100 ! voice-port 1/0/0 ! dial-peer voice 01962 voip  destination-pattern 01962  session target ipv4:10.80.80.2  req-qos controlled-load  acc-qos controlled-load