4A0-103 Sample Questions Answers

A separate label is used for each interface that the FEC is advertised on.

It uses fewer label resources than a per-interface label space.

It is typically used when the device has ATM or Frame Relay interfaces.

It uses more label resources than a per-interface label space.

A single label may be assigned to an FEC and used across all interfaces of the same router.

It is only valid when the LDP peers are directly connected over an interface, and the label is only going to be used for traffic sent over that interface.

LSPs must always terminate on a system ID.

MPLS and RSVP must be enabled on all routers.

Interfaces must be individually created in RSVP.

Path definitions must include at least one hop entry.

Admin groups can be configured using the command "configure>router>mpls>admin-group".

CSPF uses the information defined by admin groups when paths are computed for constraint-based LSPs.

By default, interfaces for which MPLS has been enabled are in the default admin group.

A LSP can make use of admin groups for constraint-based path calculations by including or excluding the admin group

The LSP is in the administrative down state.

The router's router ID overlaps another.

The router's interfaces do not have LDP running.

The router's system interface requires an IP address

RSVP-TE

TDP

LDP

ADP

MPLS-TE

The router has new entries added for the given FEC in its LIB.

The router has new entries added for the given FEC in its FIB.

The router generates a single label for the given FEC and advertises it to all its peers,

The router has multiple LSP tunnels for the given FEC.

The LSP can also use facility backup.

The LSP is limited to node protection.

You cannot request bandwidth on the protected LSP.

Node protection can be disabled.

Fast reroute requires you to manually define detour paths.

Fast reroute provides path protection close to the failure point

Fast reroute performs automatic path calculation and signaling.

Fast reroute protects both primary and secondary paths.

The packet will be label switched; the outer label TTL will be 249 and the inner label TTL will be 250.

The packet will be label switched; the outer label TTL will be 249 and the inner label TTL will be 251.

The packet will be label switched; both the outer label TTL and the inner label TTL will be 250.

The packet will be label switched; both the outer label TTL and the inner label TTL will be 249, because they must be the same.

Router R1

Router R4

Router R2

Router R3

show router mpls Isp "LSP 1" originate

show router mpls Isp "LSP 1" path detail

show router rsvp session originate

show router rsvp session "LSP 1"

RIPv2-TE

CSPF

OSPF-TE

ISIS-TE

RSVP-TE

CSPF looks for the delta bandwidth, taking down the first path if necessary.

CSPF looks for the delta bandwidth, implementing make-before-break.

After 5 failed attempts to find the bandwidth requested, the head end disables the LSP.

CSPF looks for the entire bandwidth requested, implementing MBB.

By defining new LSAs for the IS-IS protocol.

By utilizing the OSPF opaque LSAs to maintain interoperability with OSPF routing domains

By defining new TE extension TLVs to the IS-IS protocol.

By enabling CSPF algorithm extensions that allow link state TE to be implemented.

The router must build the Path State Block (PSB).

The router must build the Reservation State Block (RSB).

The router must build the Session State Block (SSB)

The router must send the second RESV refresh message.

The router must receive the second PATH refresh message.

The packet can only be forwarded as an unlabeled packet.

The packet can be forwarded as a labeled or unlabeled packet, depending on the received label value.

The packet can be forwarded as a labeled or unlabeled packet, depending on the destination IP address in the payload

The packet can only be forwarded as a labeled packet.

Independent control mode.

Ordered control mode.

Liberal label retention.

Conservative label retention.

Downstream on demand

Label request message

Notification message

Address message

Keepalive message

Initialization message

Hello message

Local FECs not included in the 192.168.1.0/24 address space and the system IP FEC.

Only the system IP FEC appears in the LIB.

Any local FECs, except those with a 24-bit mask.

Local FECs in the 192.168.1.0/24 address space.

When the interface to the peer router is down.

When router R1 has no route to the peer address 10.10.10.2.

When LDP is not configured on the peer router's interface.

When the targeted session is not configured.

TRUE

FALSE

It supports IGP-based LSPs.

It supports constrained path LSPs.

It does not support loose explicit path LSPs.

It is recommended for use in Traffic Engineering applications.

It cannot be used with facility backup fast reroute.

100Mbps

200Mbps

300Mpbs

600Mbps

700Mbps

It allows link LDP to be configured on the edge devices only.

It is used to signal the transport labels in the provider core.

It allows selective control over which devices are configured for LDP.

It is used to signal the service labels in the provider core.

Each PLR signals a bypass tunnel that avoids the next-hop downstream router.

When a failure occurs, the PLR pushs an additional label onto the label stack.

No bypass tunnel is established if the PLR cannot provide node protection.

The head-end router sets the local protection desired flag in the session attribute object.

The PLR sends it downstream with the RRO.

The PLR sends it downstream with the ERO.

It associates all detours with the source PLR.

The MP sends it upstream with the RESV message.

RIB

FIB

LIB

LFIB

It sets the address to the system address of the head-end router.

It sets the address to the next upstream hop from the ERO.

It sets the address to the next upstream hop from the PSB.

It sets the address to the next upstream hop from the RRO.

All routers along the path, R1, R2, and R3 can be PLRs.

If the R1-R2 link fails, router R4 becomes an MP.

If the R2-R3 link fails, router R3 becomes a PLR.

Router R1 is the LSP head-end and can be a PLR.

The LSP will switchover to another path if a failure occurs.

The LSP will switchover to a better path as soon as it is available.

CSPF must be enabled for this LSP to attempt to find a better path.

The LSP will switchover to a better path in a MBB fashion.

An IGP route takes priority over a transport tunnel.

Both LDP and RSVP-TE based tunnels can be used.

MPLS tunnels can be used to resolve the prefixes learned via IGP.

Multiple MPLS tunnels can be installed in the FIB.

Send a PathTear message towards router R6.

Send a PathTear message towards router R1.

Send a ResvTear message toward router R6.

Send a ResvTear message toward router R1.

The penultimate router will forward packets to the eLER, based on the IP header.

The eLER will receive packets with a top label value of 0.

The eLER will receive packets with a top label value of 3.

The penultimate router will pop the top label from the packets.

10.32.1.2

10.1.4.78

10.48.1.1

10.1.2.2

Router R1

Router R2

Router R3

Router R4

Router R5

125 Mbps

500 Mbps

625 Mbps

2000 Mbps

The inner label is the IPv4 Explicit Null. The outer label is the MPLS transport label,

The inner label is an MPLS transport label. The outer label is the IPv4 Explicit Null.

The inner label is the IPv6 Explicit Null. The outer label is an MPLS transport label.

The inner label is an MPLS transport label. The outer label is the IPv6 Explicit Null.

R4 (10.10.10.4) has established a link protection tunnel.

R6 (10.10.10.6) has established a link protection tunnel.

R2 (10.10.10.2) has established a node protection tunnel.

R1 (10.10.10.1) has not established a node protection tunnel.

The time router R2 takes to receive a PATH Error message from router R4.

The time router R2 takes to find out a number of RSVP Hello messages have been missed.

The time router R2 takes to send a PATH Tear message to the head-end router.

The time router R2 takes to receive a PATH message from router R4 after a PATH refresh interval.

The tail-end router performs the CSPF calculation for an LSP.

CSPF calculations are always performed on RSVP-TE based LSPs.

The head-end router performs the CSPF calculation for an LSP.

Each downstream router performs its own CSPF calculation for an LSP.

iLER

LER

LSR

PE

eLER

The customer's Layer 3 header is removed at the iLER.

The customer's Layer 2 header is removed at the iLER.

The customer's Layer 3 header is removed at the eLER.

The customer's Layer 2 header is removed at the eLER.

Enable the Idp-over-rsvp feature on all PEs and ABRs along the LSP tunnel.

Configure Link-LDP sessions between each PE-ABR and ABR-ABR pair.

Configure RSVP-TE LSPs in each area between each PE-ABR and ABR-ABR pair.

Configure T-LDP sessions with the tunneling option.

It supports traffic protection using IGP equal cost paths.

It supports CAC to prevent resource overbooking.

It supports LSPs with traffic engineering constraints.

It supports LSPs that follow the IGP best path.

PE, P

P, PE

PE, CE

CE, PE

CE, P

RSVP LSPs must exist between each PE-ABR pair, or ABR-ABR pair in each area.

When LDP-over-RSVP is active, the LDP prefixes are resolved to a physical egress interface.

Targeted sessions must exist between all routers along the tunnel path.

Link LDP sessions must exist between each ABR-ABR pair in each area.

If Shared Explicit reservation style is used, 400Mbps is reserved.

If Shared Explicit reservation style is used, 700Mbps is reserved.

If Fixed Filter reservation style is used, 400Mbps is reserved.

If Fixed Filter reservation style is used, 300Mbps is reserved.

The inner label will be exchanged with the MPLS outer label.

The inner label will be exchanged for a new label.

The outer label will be exchanged for a new label.

All labels will be exchanged for one new label.

All labels will be exchanged for an equal number of new labels.

When the reserved bandwidth goes above 80M.

When the reserved bandwidth goes above 40M.

When an additional 80M bandwidth is reserved.

When an additional 40M bandwidth is reserved.

Push an additional label onto the label stack.

Pop the label.

Swap the label.

Pop the label and push an additional label onto the label stack.

Both LSP-3 and LSP-4 take R1-R2-R4-R6.

Both LSP-3 and LSP-4 take R1-R3-R5-R6.

LSP-3 takes R1-R3-R5-R6 and LSP-4 takes R1-R2-R4-R6.

LSP-3 takes R1-R2-R4-R6 and LSP-4 takes R1-R3-R5-R6.

CSPF randomly chooses one of the equal cost paths for the two LSPs.

All FECs with a prefix of 192.168.1.0/30.

Local FECs with a prefix of 192.168.1.0/30.

All FECs excluding 192.168.1.0/30.

Local FECs excluding 192.168.1.0/30.

Each implementation can use them as they see fit.

They are used to carry the Ethertype value.

They are used to carry the TTL value.

They are used to carry QoS classification.

They are used to carry fragmentation flag information

Ordered control mode; downstream on demand.

Ordered control mode; downstream unsolicited.

Independent control mode; downstream on demand.

Independent control mode; downstream unsolicited.

Conservative label retention

Liberal label retention.

Downstream on demand.

Downstream unsolicited.

Disable route summarization on router R3

Enable LDP aggregate prefix match

Create an import policy to accept these FECs

Disable LDP exact match on the specified FECs

show router ldp default

show router ldp parameters

show router ldp settings

show router mpls settings

show router mpls label-options

RSVP-TE operates in a downstream unsolicited label advertisement mode.

RSVP-TE makes use of ordered control mode.

RSVP-TE is an MPLS signaling protocol, based on the resource reservation protocol.

RSVP-TE enables the establishment of explicitly routed LSPs that can be automatically routed away from network failures

RSVP-TE supports explicitly routed LSPs using either loose or strict route definitions.

The PLR issues a RSVP path message to the destination router to request the address of the MP.

The PLR learns the address of the MP from the ERO.

The PLR learns the address of the MP from the RRO

The PLR learns the address of the MP from the targeted RSVP hello message.

The PLR does not need to know the address of the MP.

Router R1

Router R2

Router R3

Router R4

Router R5

It uses a UDP connection with an arbitrary port number.

It uses a UDP connection with well known port number 646.

It uses a TCP connection with an arbitrary port number.

It uses a TCP connection with well known port number 646.

The LSP will stay on the current path indefinitely unless another failure occurs.

The LSP will stay on the current path until the resignal timer expires.

The LSP will switchover to R1-R2-R3-R5-R6 after the resignal timer expires.

The LSP will switchover to R1-R3-R5-R6 after the retry timer expires.

R1, R2, and R4 can be PLRs; R6 is the MP.

R1, R2, and R4 can be PLRs; R2, R4, and R6 are MPs.

R1, R2, R3, R4, and R5 can be PLRs; R6 is the MP.

R1, R2, R3. R4, and R5 can be PLRs; R2, R4, and R6 is the MP.

LSPs must always terminate on a system ID.

MPLS and RSVP must be enabled on all LSRs.

CSPF must be enabled.

Path definitions must include at least one hop entry.

It uses a UDP connection with an arbitrary port number.

It uses a UDP connection with well-known port number 646.

It uses a TCP connection with an arbitrary port number.

It uses a TCP connection with well-known port number 646.

The router 10.10.10.1 is a PLR providing node protection for the router 10.10.10.3.

One-to-one fast reroute protection is requested by an LSP.

The bypass-link tunnel is used to avoid the link with the egress interface address 10.3.4.4.

The bypass-node tunnel is used to avoid the next-hop downstream router 10.10.10.3.

A path definition can have both loose and strict hops.

A path definition can be configured with loose hops only.

A path definition is configured on the head-end router only,

A path definition is not required if CSPF is enabled on an LSP.

Independent control mode, downstream on demand

Independent control mode, downstream unsolicited

Ordered control mode, downstream on demand

Ordered control mode, downstream unsolicited

Router R4 swaps both the RSVP-TE LSP label and LDP transport label received with new labels,

Router R4 swaps the VPN service label received with a new label.

Router R4 uses the same RSVP-TE LSP label as the one received from router R3.

Router R4 uses the same LDP transport label as the one received from router R3.

The time router R4 takes to send a PATH Error message toward the head-end router.

The time router R4 takes to detect RSVP Hello message timeout from router R6.

The time router R4 takes to send a RESV Error message to the head-end router.

The time router R1 takes to signal an alternate path through router R3.

The MPLS TTL values are incremented at each request.

The router uses MPLS Echo Request packets that are IP-routed.

The router collects hop information along the tunnel's path.

The router performs an unidirectional LSP test.