4A0-103 Alcatel-Lucent Multi Protocol Label Switching Questions and Answers

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.

Both the primary and secondary paths are explicitly defined.

The primary path is active and the secondary path is in hot standby.

The LSP defined will use the primary path and will signal the secondary path to become active if the primary path fails.

The LSP has the same source and destination for both primary and secondary paths.

Message-IDs replace individual refresh messages.

Refresh reduction applies only to reservation messages.

RSVP generates a summary-refresh message for each LSP.

An LSP state change causes an incremented Message-ID.

IGP-based LSPs are established solely from information contained in routing tables.

The constraint-based routed LSP is calculated at the ingress of the network, based on the router database and user defined constraints.

The constraint-based routed LSP is calculated at each hop of the LSP, based on the route table and user defined constraints.

IGP-based LSPs must use LDP signaling.

The Maximum Allocation Model (MAM) provides the most efficient bandwidth utilization model

In the Maximum Allocation Model (MAM), each CT receives dedicated bandwidth constraints.

In the Russian Doll Model (RDM), a CT2 LSP automatically preempts a CT1 LSP.

Using the Russian Doll Mode! (RDM), a CT1 LSP may use unreserved CTO bandwidth.

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"

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.

from prefix-list direct

match local

from protocol direct

match protocol direct

from protocol local

The path must include at least one hop.

The path may be used multiple times in a single LSP.

The path may comprise loose hop entries only.

The path must define the LSP's tail end.

The path may be used for multiple LSPs.

Administrative Groups

Shared Risk Link Groups

Strict hop LSP paths

Fast reroute

4

1

5

6

CSPF chooses a link that is a member of both administrative groups

CSPF chooses only those links that are NOT members of the green admin group

CSPF prunes the green links and uses these links for the secondary path

CSPF signals the LSP path over the green links only, and prunes all other links

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.

Label space mode

Label retention

Control mode

Keepalive factor

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.

1

2

3

4

Independent control mode, downstream on demand

Independent control mode, downstream unsolicited

Ordered control mode, downstream on demand

Ordered control mode, downstream unsolicited

Label swapping

Pushing a label on an unlabeled packet

Label allocation

Routing lookups

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.

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.

The LSP can use facility and one-to-one FRR simultaneously.

The LSP is limited to node protection.

A single protection tunnel is used for all LSPs with the same path.

A detour protection tunnel is created for the LSP.

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.

The secondary path will take R1-R3-R2-R4-R6.

The secondary path will take R1-R2-R4-R6.

The secondary path will take R1-R2-R3-R5-R6.

The secondary path will take R1-R3-R2-R4-R5-R6.

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.

IGP-based LSPs are calculated based on information contained in routing tables.

Constraint-based LSPs are calculated using the head-end router's TED.

Constraint-based LSPs must use RSVP-TE signaling.

IGP-based LSPs must use LDP signaling.

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.

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.

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.

LDP is not configured on R2.

R2 does not have a route to 10.10.10.3.

LDP is not configured on R3's interface to R2.

The targeted session is not configured on R2.

Admin groups

Hop-limit

Strict hops

TE-Metric

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.

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.

125 Mbps

500 Mbps

625 Mbps

2000 Mbps

The PLR issues an RSVP PATH message to the tail-end requesting 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 knows the address of the MP is the same as the tail-end router.

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.

ERO is used by downstream routers to determine the next-hop for the LSP.

ERO contains label information used to signal an LSP path.

ERO is not always present in the PATH message.

Each downstream router updates information inside the ERO.

Secondary_Path-1

Secondary_Path-2

Secondary_Path-3

Secondary_Path-4

The router does not have a route to reach to the peer 10.10.10.2/32.

The router does not have a route to reach to the prefix 192.10.1.2/32.

The router does not have an export policy defined to export the prefix 192.10.1.2/32 into LDP.

The router receives an invalid label for the prefix 192.10.1.2/32 from its peer.

Type 8 LSA — Link Local LSA

Type 9 LSA — Link local Opaque LSA

Type 10 LSA — Area local Opaque LSA

Type 11 LSA —AS Opaque LSA

The peer with the higher physical address.

The peer with the higher transport address.

The peer with the lower physical address.

The peer with the lower transport address.

The peer that generated the first Hello message.

A new LDP session is established on R1-R3-R6 as soon as the FIB is updated.

The LDP session remains unchanged until the existing path R1-R2-R4-R6 goes down.

A new LDP session is established on R1-R3-R6 as soon as router R1 receives a new label for router R6.

The LDP session remains unchanged until router R3 stops advertising the maximum metric for the link to router R6.

Frame mode requires multiple sessions between peers.

The lower transport address initiates the session.

Established LDP sessions run over a TCP connection.

An LDP session is established immediately after Init messages are exchanged between peers.

Conservative label retention

Liberal label retention

Downstream on demand

Downstream unsolicited

The TC field is set based on the value of the DSCP field inside the customer packet.

The TC field is set to a specific value via explicit administrative configuration.

The TC field is set to a system generated random number.

The TC field is set by the eLER.

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 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.

Per-interface label space, liberal retention mode

Per-platform label space; liberal retention mode

Per-interface label space, conservative retention mode

Per-platform label space, conservative retention mode

They list the RSVP session names that the router is refreshing,

They list the Message IDs that the router is refreshing,

They list the Tunnel IDs that the router is refreshing.

They list the LSP I Ds that the router is refreshing.

Type 10 opaque LSAs are supported by IS-IS.

Type 10 opaque LSAs are flooded to all areas of the routing domain.

Type 10 opaque LSAs are stored in an LSDB.

Type 10 opaque LSAs are used for traffic engineering support.

Link protection tunnels are established if a router is unable to establish node protection tunnels.

Link protection tunnels are only requested for a primary LSP path.

Link protection tunnels can be created for both one-to-one or facility Fast Reroute.

Link protection tunnels detour around a failed next downstream router.

Each PLR signals a protection tunnel that avoids the downstream node.

A single protection tunnel can protect all LSPs that go through the same hop.

A link protection tunnel is signaled if a node protection tunnel cannot be established.

Protection tunnels used in this LSP are also detour tunnels.

The DMP sends the DMP_Object in each detour's PATH messages.

The DMP summarizes PATH messages, giving each detour its own MSGJD.

The DMP identifies itself as the previous hop in each detour's PATH message.

The DMP sends a single PATH message containing the merged DETOUR_Objects.

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.

Liberal label retention mode

T-LDP enabled with peers to which load balancing is desired.

ECMP enabled in the config > router context.

Hashing used to select the egress label.

Export policy applied to advertise multiple labels for a given FEC.

Label bindings are distributed to other routers when explicitly requested.

Label bindings are distributed to all neighbors including non-downstream routers.

Label bindings are distributed if labels have not been received from downstream routers.

All labels received from downstream neighbors are stored in the LIB.

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

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

The outer label TTL will be 251 and the inner label TTL will be 251.

The outer label TTL will be 251 and the inner label TTL will be 252.

Per-platform label space, conservative retention mode

Per-interface label space, conservative retention mode

Per-platform label space, liberal retention mode

Per-interface label space, liberal retention mode

Send a Path Tear message towards router R6.

Send a Path Tear message towards router R1.

Send a Resv Tear message toward router R6.

Send a Resv Tear message toward router R1.

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.

The adjacency forms with the lower timeout value.

The adjacency forms with the higher timeout value.

The adjacency is in init state.

The adjacency times out after 30 seconds.

configure router mpls retry-timer 30

configure router mpls resignal-timer 30

configure router mpls retry-attempts 30

configure router mpls global-revertive 30

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.

The customer's Layer 2 header is preserved at the iLER for Layer 2 services.

The customer's Layer 2 Header is preserved at the iLER for Layer 3 services.

The service provider's Layer 2 header is added at the iLER for Layer 2 services.

The service provider's Layer 2 header is added at the iLER for Layer 3 services.

A packet arriving with label 131066 will be forwarded out interface 1 /1 /4 with label 131070.

The router is an egress router for FEC 10.10.10.221/32.

There are multiple LSPs to reach FEC 10.10.10.244/32.

The router's system address is 10.10.10.242/32.

A router will never receive a packet containing this label value.

Request a new label from the peer that provided this label.

Pop the label.

PUSH an additional label onto the label stack.

Signal a new label to the peer that sent the packet.

This configuration already is configured for FRR.

fast-reroute facility

fast-reroute one-to-one

secondary < name >

standby

Local FECs, not including those in the 192.168.1.0/24 address space.

Only system ID FECs may appear in the LIB.

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

Local FECs in the 192.168.1.0/24 address space

Static LSPs

Reserved use

Vendor proprietary use

Management LSPs

Dynamic LSPs

Type 9 LSA ?Link local LSA

Type 10 LSA ?Area local LSA

Type 8 LSA ?TE router LSA

Type 11 LSA ?Network LSA

The egress RSVP interface has 80 percent bandwidth unreserved.

LSPs can reserve an additional 9.9 Gbps bandwidth on this RSVP interface.

The head end reserves 100Mbps for the LSP.

The egress RSVP interface has 1Gbps bandwidth unreserved.

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.