4A0-107 Questions and Answers

FC H1, high

FCH1, low

FCAF, high

FCAF, low

55 Mbps / 1.1 = 50 Mbps

55 Mbps

55 Mbps + 55 Mbps * 0.1 / 1.1 = 60 Mbps

55 Mbps * 1.1 = 60.5 Mbps

The first 3 bits of the DSCP value are copied directly into the EXP field on the first network egress.

The EXP bits are set on the first network egress, based on a combination of the SAP-ingress classification and the network policy applied.

The 3 priority bits are copied directly from the dot1p header into the EXP field of the first MPLS header.

The EXP bits are set based on a default map that translates DSCP codes into internal forwarding classes on SAP-ingress.

TRUE

FALSE

Real-time

Assured

Non-conforming

High priority

In-profile

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

It will be stored in the queue’s reserved buffer space and become out-of-profile.

It will be stored in the queue’s reserved buffer space and remain in-profile.

It will contend for shared buffer space with packets from other queues.

QoS is not configured on the router.

Packets in forwarding classes "be" and "12" are being queued.

Traffic belonging to forwarding class "ef" is not experiencing queuing delays.

Traffic belonging to forwarding class "11 "will never make use of the shared buffer pool.

Out-of-profile traffic in the shared buffer pool is being dropped.

High-1

Assured

Best Effort

Expedited

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.

Once before going through each of the redundant switching fabrics.

To protect against failure of either ingress or egress card.

Once before going through the switching fabric, and once more before going onto the egress port.

Once to decide if the packet is in-profile or out-of-profile, and once more to process the packet according to its profile.

3

4

6

8

TCP port numbers

LSP EXP

DSCP

Source and destination IP addresses

Dot1p priority

Negative jitter results in a smaller than expected interval between transmitted packets.

Jitter does not have any effect on the quality of video applications.

Serialization delay is not affected by congestion.

Queuing delay is a fixed form of delay in networks.

A packet is accepted into a queue based on its priority and forwarding class.

Buffer admission control limits the number of out-of-profile packets that enter the queue.

Both high priority-only buffer space and WRED can be used in a queue.

Priority is used when a packet enters a SAP-ingress queue.

An egress unicast queue defined in a network queue policy

An ingress unicast queue defined in a SAP-ingress policy

An ingress multipoint queue defined in a SAP-ingress policy

An ingress multipoint queue defined in a network queue policy

It is important that all packets are classified in the same way at all SAP-ingress points.

Once a packet is classified to a forwarding class, it cannot change across the network.

Packet enters a node will be treated as per the local hop's configured policy.

Native IP packets entering a network port will be marked at the first network egress by default

Native IP packets entering a network port will not be marked at the first network egress by default.

Native IP packets entering a network port will be marked at the first network egress, regardless of the re-marking configuration.

16

8

32

48

56

Packets corresponding to a layer-2 service can be pre-marked on SAP-ingress.

Packets corresponding to a layer-2 service can be pre-marked on network-ingress.

Packets corresponding to a layer-3 service can be pre-marked on SAP-ingress.

Packets corresponding to a layer-3 service can be pre-marked on network-ingress.

Microflow reservations using RSVP

DSCP to EXP translation

Traffic classification

Automatic profiling and policy configuration

Buffer memory management

Traffic scheduling

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 incoming packets belonging to forwarding class “l2” are stored in the reserved buffer space.

All incoming packets belonging to forwarding class “af” are stored in the reserved buffer space.

All incoming packets belonging to forwarding class “l1” are stored in the reserved buffer space.

In-profile packets in the shared buffer space are being dropped.

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

EF, in

H1, out

BE, out

L1, in

Ensure that traffic flows conform to their traffic profile.

Log violations of metered traffic flows exceeding the CIR value set on the entity across which the traffic is moving.

Provide fairness between traffic flows, so that conforming (in-profile) traffic flows are not starved of bandwidth and/or buffer space by non-conforming (out-of-profile) flows.

Minimize packet loss and reduce end to end latency.

Ensure that variable latencies do not cluster short bursts of originally conforming packets and render them nonconforming.

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.

It sets the destination IP address of the packet.

It uses RVSP to inform other QoS capable routers how the packet should be treated.

It sets the TOS, DSCP, EXP, or DOT1p field based on classification criteria.

It can use a customer’s encapsulated data to determine a packet’s forwarding class.

EF

H1

L1

H2

L2

The default forwarding class defined in the SAP-egress policy.

The forwarding class inherited from network ingress classification.

Best Effort.

If there is no match, packets will be dropped.

When applied at the port level for access ingress.

When applied at the FP (Forwarding Pass) level for access ingress.

When applied at the FP (Forwarding Pass) level for network ingress.

When applied at the port level for network egress.