MPLS Fundamentals

1 MPLS labels are locally significant.

A True
B False

If you want to pop a label but you want to keep the QoS information, which of these is better to use?

Explicit NULL label
Implicit NULL label

The MPLS backbone is visible to CE's?

True
False
True False

ATM data is cut into chucks of what size?

48 bytes
64 bytes
53 bytes

FEC stands for:

Forwarding Equivalence Channel
Forwarding Edge Channel
Forwarding Edge Class
Forwarding Equivalence Class

TLDP send targeted "Hello" messages to multicast address 244.0.0.2.

True
False
True False

MPLS can be carried over which Layer 2 technology? (Multiple answers may apply)

HDLC
Ethernet
PPP
ATM
Sonet/SDH
All of the above

Which LSR can do the action "Pop"? (Multiple answers may apply)

Egress LSR
Intermediate LSR
Ingress LSR

Packets enter the LSP at the _________ LSR. (Fill in the blank)

Ingress
Egress

Packets leave the LSP at the _________ LSR. (Fill in the blank)

Ingress
Egress

In a typical IP network routers take independent forwarding decisions.

True
False
True False

What happens to the TTL when a packet leaves MPLS? (Multiple answers may apply)

A It is decremented by one
B It is copied from the label stack to the IP header
C Nothing

Which of these statements in TRUE?

Packets with the same label always have the same FEC
Packets with the same FEC always have the same label

Packets can leave a LSP at any point along it.

True
False
True False

RSVP needs to use the underlying IGP for path selection

True
False
True False

ATM is based on:

Frame-switching
Packet-switching
Cell-switching

LDP makes its own path selection decisions.

True
False
True False

MPLS labels can vary in length.

True
False
True False

The MPLS header is how many bits long?

48 bits
3 bits
53 bits
32 bits
20 bits

Which of these protocols is used to distribute the outer label? (Multiple answers may apply.)

MG-BGP
TLDP}
RSVP
LDP

MPLS was defined by the IETF in what year?

A 1997
B 2007
C 1987

If an LSR receives a label of 3, what does it mean?

Do PHP
Take a closer look at this packet
This is the bottom label in the stack

How many layers are there in the OSI model?

A 5
B 6
C 7
D 8

Which of these are label distribution modes? (Multiple answers may apply)

Downstream on demand
Unsolicited downstream
Unprecedented downstream
Unsolicited upstream
Upstream on demand

Which of these are label distribution modes? (Multiple answers may apply)

Downstream on demand
Unsolicited downstream
Unprecedented downstream
Unsolicited upstream
Upstream on demand

In which of these label distribution modes will the LSR send labels without being asked to do so?

Downsteam on demand
Unsolicited Downstream

LSPs are bi-directional.

True
False
True False

Which port is an LDP "Hello" message sent on

A TCP 636
B UDP 656
C UDP 636
D TCP 656
E UDP 646
F TCP 646

Which of these control modes only creates a label binding for a FEC if it has received a label binding from the next-hop or is the egress LSR?

Downstream LSP control mode
Upstream LSP control mode
Ordered LSP control mode
Dependent LSP control mode
Independent LSP control mode

The CE router needs to have MPLS running on it.

True
False
True False

How many bytes does an MPLS header add to the size of the packet?

A 32
B 1
C 8
D 4

The EXP field of the MPLS header is used for what?

Indicates the bottom of the stack
Defines class of service
Label mapping
Time to Live

MPLS packets are routed through a network.

True
False
True False

Inside the LDP identifier there is a 4 byte field that identifies what?

A Label distribution mode
B LSR
C LFIB
D LSP
E Label space

What is the length of the LDP identifier?

32 bits
4 bytes
4 bits
6 bytes

In LDP, the signaling of the labels to neighbors is in the opposite direction to the packet flow.

True
False
True False

Which label is used to identify the LSP?

Inner
Outer
Both

What does a service provider use to separate customers VPNs?

Outer label
EXP field in MPLS header
Inner label
Destination IP address
LDP ID

Which of these protocols require the neighbor to be directly connected?

A LDP
B MG-BGP
C TLDP

Different VPN customers can use over-lapping IP addresses.

True
False
True False

An intermediate LSR can do what action? (Multiple answers may apply)

Swap
Push
PHP

Which label is examined when there are multiple labels in the stack?

A Both
B Outer
C Inner

What is another name for ingress LSR? (Multiple answers may apply)

LSP
P
LER
PE

IP packets are all the same size.

True
False
True False

When using LDP the LSP will follow the same path as the IGPs shortest path.

True
False
True False

Intermediate LSR's will look at the IP header on a packet.

True
False
True False

Which LSR can do the action "Push"? (Multiple answers may apply)

Egress LSR
Ingress LSR
Intermediate LSR

Match the label number with it's name:

Label 0              Explicit NULL
Label 3              OAM
Label 1              Implicit NULL
Label 14            Router Alert

VCI stands for:

Virtual _______ Indicator

Which of these ports is used to negotiate LDP parameters?

UDP 636
TCP 636
UDP 646
TCP 646
UDP 656
TCP 656

ATM headers are locally significant.

True
False
True False

Match the protocol with the traffic identifier:

ATM                   Timeslots
Frame Relay        VPI/VCI
TDM                   DLCI

Match the RSVP message with the correct statement:

Path Message      Is sent in the upstream direction
RESV Message   Is sent in the downstream direction