350-001 Cisco Certified Internetworking Expert Study Guides

Demo Question 13.

The relevant part of a EliteCertify router's configuration is displayed below: Classed-Based marking has been configured on this EliteCertify router as shown above to sort traffic into classes for appropriate treatment by upstream routers. Unfortunately, traffic received by an upstream router on the 192.168.1.0/24 network is not appropriately marked; VoIP packets are not marked *EF* and packets previously set by end-users as CS3 and EF are not remarked to DSCP 00000. Which of the following issues could be the cause of the problem? (Select all that apply).

A. Using NBAR to classify RTP traffic requires that IP CEF be disabled.
B. The VoIP-RTP access list includes both even and odd-numbered ports starting from 16384; while RTP only uses even-numbered ports.
C. The router has been improperly configured to only mark traffic flowing in the wrong direction.
D. The set ip dscp default command does not mark the packet with DSCP 0000, but instead resets the command use back to Cisco IOS default settings.
E. The Class-map VoIP-Remark has been improperly configured to simultaneously match more than one traffic type.
F. None of the above


Display Answer

Answer: C, E

Explanation: The first problem is that the service policy named Policy-NoTrust is being applied to the input direction of the ethernet interface, when it should be applied in the outbound direction for the upstream routers to see the correct DSCP markings of the packets. The second problem is the fact that the keyword "match-all" is being applied to the VOIP-Remark class map. This keyword instructs the IOS that all of the criteria in the entire map must match in order to be applied. In the configuration above, only a packet that matches all three of the criteria (DSCP EF, DSCP CS3, and DSCP AF21) will be marked, instead of packets that match any one of those. In this example, the correct syntax should have been "class-map match-any VoIP-Remark"