4A0-107 Practice Exam Questions with Answers Nokia Quality of Service Certification

The slope-policy

The SAP-ingress policy

The network-queue policy

The scheduler-policy

The network-policy

The WRED-policy

The arbitrator-policy

network

scheduling

slope

SAP-ingress

network-queue

Shapeless policing at SAP-ingress only.

Shapeless policing at SAP-ingress and egress.

Biased round robin queuing at ingress only.

Soft shaping at all network interfaces.

Soft shaping at network ingress only.

Queue 6 within-CIR packets, then queue 5 within-CIR packets, then queue 5 and queue 6 above-CIR packets in round-robin.

Queue 6 within-CIR packets, then queue 5 within-CIR packets, then queue 5 and queue 6 above-CIR packets in biased round-robin.

Queue 6 within-CIR packets, then queue 5 within-CIR packets, then queue 6 above-CIR packets, and finally queue 5 above-CIR packets.

Queue 6 and queue 5 within-CIR packets in biased round-robin, then queue 5 and queue 6 above-CIR packets in round-robin.

BGP

Telnet

ICMP

SNMP

802.1p bits

Precedence

DSCP

EXP

1 multipoint and 8 unicast.

8 queues, regardless of traffic type.

8 unicast and 24 multipoint.

8 unicast and 8 multipoint.

16 queues, distributed as desired.

8

16

6

4

3

It will be discarded because the high-priority-only threshold is exceeded.

It will be queued but re-marked as "out-of-profile."

It will be queued in the reserved portion of the buffer pool and remain "in-profile."

It will be queued in the shared portion of the buffer pool but contend for shared buffer space with packets from other queues.

It will be queued in the shared portion of the buffer pool but may be dropped if the buffer utilization exceeds the start-average value of the low slope.

802.1p adds 16 bits to the Layer 2 header,

802.1p adds 16 bits to the Layer 3 header.

802.1p specifies 64 different priority levels.

802.1p uses a field in the 802.1Q header.

802.1p uses a field in the Layer 3 IP header

802.1p defines a 3-bit Class of Service field.

It is a parent scheduler.

It is the top-level scheduler.

It can allocate up to 50 Mbps of bandwidth to scheduler "low" since the bandwidth is not used by another Tier 3 scheduler.

It is a child scheduler.

It can only have queues as children.

Defining the slope of the TCP slow-start mechanism for self generated traffic.

Defining the slope of the scheduling rate per forwarding class when using HQoS.

Defining the high and low slope values when deploying buffer admission control for UDP traffic in the committed buffer pool.

Defining the high and low slope values when deploying buffer admission control for TCP traffic in the shared buffer pool.

Defining the high and low slope values when deploying buffer admission control for TCP traffic in the committed buffer pool.

Packets that arrive in a burst are immediately dropped; packets that arrive with the proper in between space are immediately.

Packets are buffered on arrival and are forwarded at an average rate conforming with PIR, typically, with a reduced burstiness.

Packets with an average arrival rate higher than PIR are immediately dropped; conforming packets are forwarded at the same rate at which they arrive.

Packets with an average arrival rate higher than PIR are buffered for future processing; conforming packets are immediately forwarded.

TRUE

FALSE

Policer 3 forwards packets as out-of-profile when its PIR bucket has 4000 tokens.

Policer 3 starts discarding low-priority packets when its PIR bucket has at least 3000 tokens.

Policer 4 forwards all its packets as out-of-profile.

Policer 4 starts discarding low-priority packets when its PIR bucket has at least 3000 tokens.

The slope-policy

The SAP-ingress policy

The SAP-egress policy

The network-queue policy

The scheduler-policy

Classification

Marking

Buffer admission control

Scheduling

To have control over the amount of the low priority packets that enter the queue.

To control any traffic flowing through the shared buffer space of the queue.

To limit the number of the TCP sessions that go into slow start during congestion.

To force the TCP algorithm to increase its transmission window upon detecting a congestion.

Queue 3 within-CIR packets, then queue 4 within-CIR packets, then queue 3 and queue 4 above-CIR packets in round-robin.

Queue 4 within-CIR packets, then queue 3 within-CIR packets, then queue 3 and queue 4 above-CIR packets in round-robin.

Queue 3 within-CIR packets, then queue 4 within-CIR packets, then queue 3 above-CIR packets, and finally queue 4 above-CIR packets.

Queue 4 within-CIR packets, then queue 3 within-CIR packets, then queue 4 above-CIR packets, and finally queue 3 above-CIR packets.

PIR = 4 Mbps, CIR = 1 Mbps

PIR = 1 Mbps, CIR = 1 Mbps

PIR = 10 Mbps, CIR = 1 Mbps

PIR = 5 Mbps, CIR = 1.25 Mbps

PIR = 1.25 Mbps, CIR = 1.25 Mbps

Each network egress port receives its own buffer pool.

Each SAP-egress port receives its own buffer pool.

All SAP-ingress ports on the same MDA share a buffer pool.

All the network ingress ports on the same MDA share a buffer pool.

Each network ingress port on the same MDA receives its own buffer pool.

PIR = 4Mbps. CIR = 1Mbps

PIR = 1Mbps, CIR = 1 Mbps

PIR = 10Mbps, CIR = 1Mbps

PIR = 5Mbps, CIR = 1.25Mbps

PIR = 1.25Mbps, CIR = 1.25Mbps

Classification rules must specify both an FC and a profile for the packets.

A network policy is applied at a physical port.

Classification is performed with behavior-aggregate statements only.

Match criteria can be chosen from dot1p, DSCP, and EXP fields in the packet.

prec

lsp-exp

src-ip

do1p

Queue parameters with which the queue will compete for bandwidth.

The level of hierarchy with which a group of schedulers is associated.

Bandwidth controls that limit each child scheduler or child queues associated with the scheduler.

The maximum bandwidth that the parent scheduler can offer its child queues or schedulers.

Interfaces, ports, SAPs

Ports, ports, MDAs

MDAs, MDAs, ports

Interfaces, interfaces. MDAs

MDAs, ports, interfaces

PIR

CIR

MBS

burst-limit

The default forwarding class for all traffic, including ICMP, is BE, which is placed in queue 1.

The SAP has been shut down.

The IP-match criteria has been misconfigured for ICMP traffic.

Queue 3 has no rate or CIR configured and thus cannot hold any packets.

The SAP-ingress policy has not been applied to the SAP.

IS-IS

RSVP

ICMP

BGP

The administrative PIR values are ignored and both operational rates are set to the minimum residual rate allowed by the hardware.

The administrative PIR value is ignored and both operational rates are set to the administrative CIR value.

They are chosen as the largest multiple of the hardware rate step that is less than or equal to the corresponding CIR/PIR administrative value.

They are chosen as the smallest multiple of the hardware rate step that is greater than or equal to the corresponding CIR/PIR administrative value.

It may exceed PIR of the queue.

It may be exceeded by the average servicing rate of the queue.

It varies depending on the traffic characteristics.

It is the rate at which packets are forwarded out of the queue.

Packets can be classified into 16 different FCs when using priority mode queuing.

This feature is available on egress SAPs within any service.

MPLS EXP bits can be changed based on multi-field classification.

If a Behavior Aggregate (BA) and Multi-field (MF) match occurs, only the MF override parameters will take effect.

If a Behavior Aggregate (BA) and Multi-field (MF) match occurs, the BA classification can override the forwarding class while the MF classification can override the profile.

Microflow reservations using RSVP

DSCP to EXP translation

Traffic classification

Automatic profiling and policy configuration

Buffer memory management

Traffic scheduling

A device that provides no differentiation between customer traffic flows.

A device that classifies and marks customer traffic.

A device that uses MPLS EXP bits to differentiate between traffic flows.

A device that creates macroflows towards the core from multiple customer sites.

A device that passes macroflows while optionally changing QoS markings.

0

min

max D. 50000

Set the CBS to 0.

Set the MBS equal to the CBS.

Set the high-priority-only equal to the MBS.

Set the MBS to 0.

Set the high-priority-only to 0.

Limiting the maximum forwarding rate of each individual policer and, at the same time, marking, packets as in-profile or out-of-profile.

Putting packets in a buffer as they are received, and marking packets as in-profile or out-of-profile as they are removed from the buffer.

Rate-limiting the collective output of several policers, and to reallocate bandwidth that is not utilized by some policers to other policers that need to use it.

Rate-limiting the collective output of several policers towards each egress FFPC, while maintaining control of the maximum overall forwarding rate.

NC, low

NC, high

BE, low

BE, high

Multi-field classification can use both MAC criteria and IP criteria in the same SAP-ingress QoS policy.

Behavior aggregate classification can use both lsp-exp and dscp in the same SAP-ingress QoS policy.

Multi-field classification cannot use both IP criteria and IPv6 criteria in the same SAP-ingress QoS policy.

Behavior aggregate classification cannot use both dot1p and lsp-exp in the same SAP-ingress QoS policy.

All out-of-profile traffic will be dropped before that of any in-profile traffic.

The discard probability slope of an in-profile traffic is steeper than that of an out-of-profile traffic.

When the shared buffer utilization reaches 55%, both in-profile and out-of-profile packets may be dropped.

The maximum probability with which an out-of-profile packet can be dropped is higher than that of an in-profile packet.

When the shared buffer utilization is at 61%, only in-profile packets are currently in the shared buffer pool.

All buffer space is initially allocated to access pools, and some of it is reallocated to network pools if network interfaces are configured on it.

All buffer space is initially allocated to network pools, and some of it is reallocated to access pools if service SAPs are configured on it.

Buffer space is allocated 50% for access pools and 50% for network pools.

Buffer space is allocated 25% for access pools and 75% for network pools.

PIR

CIR

Level

Weight

An SLA is used to provide automated, real-time testing and alarming for throughput, latency, and jitter across a provider's network.

An SLA is an agreement between a customer and a provider that dictates the treatment of customer traffic across the provider's network.

An SLA allows customers to control all traffic within the service provider's network by prioritizing their traffic over others as desired.

An SLA allows a customer to pre-mark traffic and ensure that traffic is treated as per the agreement within the provider's network.

An SLA is a standard set of network QoS policies that a provider shares to all its customers, allowing them to better understand the treatment of traffic within the provider's network.

EXP markings on transit control traffic are not set correctly.

The priority of all self-generated traffic needs to be lowered to allow all other traffic to take precedence.

The priority of various control packets requires special treatment throughout the network.

The BGP process is consuming too many CPU cycles and is impacting OSPF performance.

It enables fine-tuned SLA control that is not possible when using a common set of queues for all L2/L3 services.

It enables CFHP and hierarchy scheduling (egress) for each network interface.

It improves scalability by allowing the use of queues instead of the default set of policers used on network egress.

It allows for enforcing bandwidth reservations of the LSPs that are used by the SDPs configured on the network interfaces.

It smooths out traffic bursts.

It drops the packets when average peak rate is exceeded.

It may additionally color the packets as they arrive.

It buffers the packets at its output before sending them out.

The default scheduler spends an equal amount of time servicing each queue that has traffic to be sent out.

Queue-type can be configured as best-effort, expedite, or auto-expedite.

A queue will be serviced as expedited if its type is configured as expedited, regardless of the forwarding classes mapped to it.

A queue configured as auto-expedited will be an expedited queue as long as no Best Effort FC is mapped to it.

In order to mark Layer 2 traffic, sgt-qos will set various ToS bits.

DSCP bits can be set per application, per routing instance.

The DSCP marking stays nc1 for all applications. Only the internal FC is manipulated across different applications.

In order to mark Layer 2 self-generated traffic, network interfaces must be set to dot1Q.

The internal forwarding class for self-generated traffic is set once and applied to the base router and all VPRN instances.

When using profile-mode queues, traffic that is marked as in-profile on ingress and scheduled in the above-CIR loop will still be considered as in-profile at egress.

When an HQoS strategy using an egress port-scheduler has been deployed, Tier 1 receives its scheduling rates based on the amount of egress bandwidth available for each forwarding class.

The greater the difference between PIR and CIR rates in a queue, the less likely a CIR will be provided.

Packets scheduled out of high-priority queues in the default scheduler will have a lower chance of packet loss at the expense of incurring a higher probability of delay.

When using priority-mode queues, traffic that is marked as in-profile on ingress and scheduled in the above-CIR loop will be considered as in-profile at egress.

8

3

5

6

The IOM3 adds more memory to both forwarding complexes which increases the total number of queues available.

The IOM3 only contains a single forwarding complex which reduces the number of queues used.

The IOM3 allows multiple forwarding classes to be assigned to a single queue.

The IOM3 allows queues to be dynamically allocated between ingress and egress.

The IOM3 has a larger CPU capable of tracking active hardware queue utilization and adjusting memory allocation accordingly.

Profile mode queues

Priority mode queues

1 queue

3 queues

3 forwarding classes

1 forwarding class, with 2 subclasses

1 forwarding class, with 3 subclasses

When queues use shared buffer space, buffers are more efficiently utilized.

Queues that use reserved buffer space will have memory available for their reserved portion.

When a queue is not using its reserved portion, other queues can use it.

Using reserved buffer space prevents a queue from being starved of buffer resources by other queues.

HQoS schedulers cannot be children of an egress port-scheduler.

HQoS schedulers provide a dynamic method of allocating scheduling resources to queues.

HQoS scheduler policies can be applied to an MDA to schedule network ingress traffic.

A scheduler policy applied to multiple SAPs within the same service will result in a single hardware scheduler operating across all SAPs within the service.

The primary contributors to latency are distance, scheduling, and congestion.

The weighted round robin scheduling algorithm will result in more delay for high priority traffic than the regular round robin algorithm.

The round robin scheduling algorithm will result in less jitter for low priority traffic than a strict priority scheduler.

Packet loss can be reduced by decreasing the amount of buffer space available to a queue.

Latency can be reduced by increasing the amount of buffer space available to a queue.

All forwarded packets will be in-profile

Packets forwarded above CIR will be marked out-of-profile and the rest will be in-profile

Excess packets that arrive within a burst larger than CBS will be forwarded as out-of-profile

All forwarded packets will be out-of-profile

A customer is complaining that his VoIP traffic is being dropped even though it is sending the correct DSCP markings. Packets are not being dropped on ingress.

A customer is complaining that his VoIP traffic is being dropped even though it is sending the correct DSCP markings. Packets are being dropped on ingress.

A commercial builder has requested numerous dot1Q epipes, VPRNs, and VPLS services to a business park and is only paying up to a maximum 200Mbps.

An equipment manufacturer has requested a NULL epipe service that will transparently pass dot1Q between the new location and national headquarters.

True

False

The process happens only before the packet goes through the switching fabric.

The process happens only before the packet goes onto the egress port.

Marking/remarking the packets is for future classification.

Marking/remarking the packets will occur right after classification of the packet.

The DSCP value will be set to af21.

The DSCP value will be set to af23.

The DSCP value will remain as ef.

The EXP value, in the MPLS headers, will be set to 4.

The EXP value, in the MPLS headers, will be set to 3.

DSCP is part of the Layer 3 header.

DSCP is a 6-bit field.

DSCP specifies eight different priorities.

DSCP specifies four precedence levels.

DSCP is part of the Layer 2 header

DSCP specifies 128 different per-hop behaviors.

The egress port scheduler takes the ratio of requested bandwidth to total bandwidth request from all children. It allocates bandwidth fairly, using these percentages and not exceeding the egress interface speed.

The egress port scheduler allocates bandwidth based on a WRR distribution method that takes into account the CIR and PIR requested at each level and the max speed, either default or configured, on egress.

The egress port scheduler allocates bandwidth on a first come, first served distribution method that takes into account the total CIR and PIR requested at each level and the max PIR requested from a single level.

The egress port scheduler will limit the bandwidth offered to the egress port based on the over-subscription factor, provisioned under the router interface, while using a WRR scheduler for the remaining bandwidth.

The egress port scheduler will use the Russian Dolls Method to allocate bandwidth to each level of requested bandwidth. HPO-Only is automatically set to 100%, allowing only high priority traffic to be buffered during congestion.

WRED monitors the shared buffer space utilization over a period of time.

WRED disables the TCP slow-start congestion control mechanism.

WRED uses two configurable slopes for each buffer pool: a high slope and a low slope.

WRED uses the shared buffer utilization, instead of the individual queue depth, to get a better picture of the average resource utilization of the shared buffer space.

WRED polices the shared buffer pool and marks all packets above a certain rate as "discard eligible."

Network ingress port

Epipe ingress SAP

ES egress SAP

Ingress MDA

VPRN ingress interface

Shared buffer space