Free Nokia Virtual Private LAN Services Practice Questions

Sample Practice Questions

Try these 10 sample questions from the Nokia Virtual Private LAN Services practice bank. Each includes the answer and explanation. Continue with the interactive practice above to review the full question set.

1. 1In the SR OS service model, what does a service access point identify?

   1. A.The customer-facing service interfaceCorrect answer: A
   2. B.The provider-facing service tunnel
   3. C.The remote service tunnel endpoint
   4. D.The inter-router transport interface

   Explanation: Nokia states: "The Service Access Point (SAP) identifies the customer-facing interface with null, dot1, or qinq encapsulation." A SAP identifies the customer-facing attachment, whereas an SDP connects routers.

   Reference: Service components — Service components

2. 2What network does VPLS present to customer sites connected through the provider?

   1. A.A set of unrelated routed subnets
   2. B.A point-to-point serial circuit
   3. C.A single bridged LAN domainCorrect answer: C
   4. D.A provider-managed IP routing domain

   Explanation: Nokia says VPLS "allows the connection of multiple sites in a single bridged domain over a provider-managed IP/MPLS network." The customer sites appear to share a LAN.

   Reference: Virtual Private LAN Service — VPLS service overview

3. 3What happens when a Layer 2 packet remains larger than the VPLS service MTU after service delineation overhead is removed?

   1. A.The VPLS forwards only the first fragment.
   2. B.The VPLS expands its service MTU.
   3. C.The VPLS discards the packet.Correct answer: C
   4. D.The VPLS fragments the packet.

   Explanation: Nokia states: "VPLS services do not support fragmentation and must discard any Layer 2 packet larger than the service MTU after the service delineation overhead is removed." The packet is discarded rather than fragmented.

   Reference: Virtual Private LAN Service — IP interface MTU and fragmentation

4. 4In a fully meshed VPLS core, how is a packet received on a mesh SDP handled with respect to other mesh SDPs in the same service?

   1. A.It is never forwarded to other mesh SDPs.Correct answer: A
   2. B.It is forwarded to other mesh SDPs only for known unicast.
   3. C.It is forwarded to other mesh SDPs only for unknown unicast.
   4. D.It is forwarded to other mesh SDPs only for multicast.

   Explanation: Nokia says "packets received from a mesh SDP are never forwarded to other mesh SDPs within the same service." This split-horizon rule avoids loops in the fully meshed core.

   Reference: Virtual Private LAN Service — Split horizon SAP groups and split horizon spoke SDP groups

5. 5What resilience does MC-LAG add beyond link redundancy in Nokia's implementation?

   1. A.Node-level redundancy in addition to link redundancyCorrect answer: A
   2. B.Link redundancy without protection from node failure
   3. C.Node redundancy without protection from link failure
   4. D.Neither link nor node redundancy

   Explanation: Nokia calls MC-LAG "an extension to the LAG feature to provide not only link redundancy but also node-level redundancy." This protects against failure of a peer node as well as an individual link.

   Reference: Multi-Chassis LAG and Pseudowire Redundancy Interworking — Overview > MC-LAG

6. 6Which PBB-VPLS mechanism helps reduce the number of customer MAC addresses visible in the core?

   1. A.MAC hidingCorrect answer: A
   2. B.Per-customer MAC learning in every core node
   3. C.Per-customer MAC advertisement to every core node
   4. D.Per-customer MAC replication to every core node

   Explanation: Nokia attributes increased scalability to "MAC hiding, service multiplexing, and pseudowire aggregation." MAC hiding is the mechanism relevant to the number of customer MACs exposed in the core.

   Reference: PBB-VPLS — Overview

7. 7Which statement describes an SR OS service distribution point?

   1. A.It is a unidirectional tunnel between routers.Correct answer: A
   2. B.It is a bidirectional tunnel between routers.
   3. C.It is a customer-facing port on one router.
   4. D.It is a tunnel dedicated to exactly one service.

   Explanation: Nokia defines the SDP as "the unidirectional transport tunnel that connects services between two routers." Its direction and transport role distinguish it from a customer-facing SAP.

   Reference: Service components — Service components

8. 8What distinguishes a local VPLS service from a distributed VPLS service?

   1. A.Local services use multiple routers; distributed services use only one router.
   2. B.Local services use one service router; distributed services use more than one.Correct answer: B
   3. C.Local services use routing tables; distributed services use forwarding databases.
   4. D.Local services use MPLS tunnels; distributed services use only Ethernet ports.

   Explanation: Nokia describes a VPLS service as connecting SAPs "on one (which is considered a local service) or more (which is considered a distributed service) service routers." The number of service routers distinguishes the two.

   Reference: Virtual Private LAN Service — VPLS service overview

9. 9A virtual port has a port MTU of 1520 bytes and service delineation overhead of 4 bytes. What is the largest VPLS service MTU it can support while becoming operational?

   1. A.1524 bytes
   2. B.1516 bytesCorrect answer: B
   3. C.1512 bytes
   4. D.1520 bytes

   Explanation: Nokia states that a virtual port cannot become operational unless "the configured port MTU minus the virtual port service delineation overhead is greater than or equal to the configured VPLS service MTU." Here 1520 minus 4 is 1516 bytes.

   Reference: Virtual Private LAN Service — IP interface MTU and fragmentation

10. 10A VPLS frame enters a SAP in a split horizon group. Which group members are excluded from receiving a copy?

    1. A.Only the other SAPs in that group
    2. B.Only the spoke SDPs in that group
    3. C.Other SAPs and spoke SDPs in that groupCorrect answer: C
    4. D.Neither SAPs nor spoke SDPs in that group

    Explanation: Nokia states: "Traffic arriving on an SAP or a spoke-SDP, or both, within a split horizon group is not copied to other SAPs and spoke-SDPs in the same split horizon group". Members of other groups can still receive copies.

    Reference: Virtual Private LAN Service — Split horizon SAP groups and split horizon spoke SDP groups