300-610 practice question 7 of 35

A small company hosts several critical applications on bare-metal servers connected via iSCSI protocol to shared JBOD storage. One of the critical…

A small company hosts several critical applications on bare-metal servers connected via iSCSI protocol to shared JBOD storage. One of the critical applications is experiencing latency issues, which the engineering team suspects is due to incorrect prioritization for iSCSI traffic. An engineer must update the network QoS settings to prioritize iSCSI traffic with these requirements: iSCSI traffic must be prioritized. The solution must be able to differentiate between different types of iSCSI traffic. The solution must be scalable because iSCSI traffic is expected to increase in the future. The solution must not disrupt other traffic. Which two configurations must the engineer apply to the devices on the network to meet the requirements? (Choose two.)

Answer options

A: class-map match-all ISCSI match access-group name ISCSI policy-map QoS_Policy class ISCSI priority percent 50 Correct answer

B: ip access-list extended ISCSI permit tcp any any eq 3260 Correct answer

C: policy-map QoS_Policy class class-default priority percent 100 police rate 100 mbps burst 5000 packets conform-action transmit exceed-action drop

D: ip access-list extended iSCSI permit tcp any any eq 865

Correct Answer:

A. class-map match-all ISCSI match access-group name ISCSI policy-map QoS_Policy class ISCSI priority percent 50; B. ip access-list extended ISCSI permit tcp any any eq 3260

Explanation

To meet the requirements, a Modular QoS CLI (MQC) configuration is needed. First, an access control list (ACL) is required to classify the iSCSI traffic. Option B correctly creates an extended ACL named ISCSI that matches traffic destined for TCP port 3260, the standard port for iSCSI. Second, a policy must be created to prioritize this classified traffic. Option A correctly defines a class-map that uses the ISCSI ACL for matching, and then a policy-map that assigns a 50% priority queue to that class. Together, these two configurations correctly identify and prioritize iSCSI traffic.

Why Incorrect

C. This option configures the class-default queue, which applies to all other traffic, not specifically iSCSI. Prioritizing all default traffic is not the requirement.
D. This ACL matches TCP port 865, which is not the standard IANA-assigned port for iSCSI traffic (which is 3260).

References

1. Cisco Nexus 9000 Series NX-OS Quality of Service Configuration Guide, Release 10.2(x), "Configuring Classification" chapter. This document shows the syntax for creating an ACL and using it within a class-map via the match access-group command.

2. Cisco Nexus 9000 Series NX-OS Quality of Service Configuration Guide, Release 10.2(x), "Configuring Queuing and Scheduling" chapter. This document explains the use of the priority command within a policy-map to provide strict priority scheduling for a traffic class.

3. Internet Assigned Numbers Authority (IANA), "Service Name and Transport Protocol Port Number Registry". The registry officially lists port 3260 for the iSCSI service name over TCP.

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