Nokia NRSII 4A0-C04 Set3 [101-150] Flashcards
(33 cards)
Question 101
Which of the following is a characteristic of a VPLS?
A. All SAPs of a VPLS belong to the same broadcast domain.
B. When a new site is added, all the existing sites need to be shutdown and re-provisioned.
C. An additional T-LDP session is required between PEs for each additional VPLS that is provisioned.
D. Multiple VPLSes on the same router share a single MAC FDB.
A. All SAPs of a VPLS belong to the same broadcast domain.
Answer Explanation:
In a Virtual Private LAN Service (VPLS), all SAPs (Service Access Points) of the same VPLS instance participate in the same Layer 2 broadcast domain, effectively emulating a LAN over a packet-switched network. This means broadcasts, unknown unicasts, and multicasts are flooded across all active remote and local SAPs of that VPLS.
B is incorrect because VPLS is designed to allow new sites to be added without impacting existing ones.
C is incorrect because a single T-LDP session can signal multiple VPLS instances.
D is incorrect because each VPLS instance has its own MAC FDB (Forwarding Database), not shared across instances.
Question 102
The CEs use BGP and export policies to advertise their local prefixes with the VPRN on their PEs. If the VPRN is functioning properly, which of the following commands will succeed when performed on router R1?
A: ping 192.168.20.1
B: oam vprn-ping 100 source 192.168.10.1 destination 192.168.20.1
C: oam vprn-ping 100 source 192.168.20.1 destination 192.168.10.1
D: ping 10.10.10.6 (router R6’s system IP)
B: oam vprn-ping 100 source 192.168.10.1 destination 192.168.20.1
Answer Explanation:
The oam vprn-ping command is used to test VPRN (VPN Routing and Forwarding) reachability between two IP addresses within the same VPRN instance.
The number 100 refers to the VPRN service ID.
192.168.10.1 is the source CE IP address connected to R1, and 192.168.20.1 is the destination CE IP address behind the remote PE.
This command sends a ping over the VPRN tunnel to validate L3 VPN connectivity, ensuring data-plane reachability between customer sites.
Choices A and D would only work if there was direct IGP or global routing reachability, which is not assumed in VPRN scenarios. Choice C has the source and destination reversed relative to R1.
Question 103
Which of the following about VPN labels is FALSE?
A: They are signaled between PE devices using MP-BGP.
B: They are swapped at each P router as a packet crosses the service provider network.
C: They are also known as the inner label or service label.
D: They indicate to the egress PE the VPRN to which a packet belongs.
B: They are swapped at each P router as a packet crosses the service provider network.
Answer Explanation:
VPN labels (also called service labels or inner labels) are used only between PE routers, not by P routers.
They are used to identify the destination VPN (or VPRN) on the egress PE.
They are not swapped at P routers. P routers operate only on the outer label (transport label), which is swapped hop-by-hop during label switching.
MP-BGP distributes VPN labels between PEs (Choice A — TRUE).
They are known as inner/service labels (Choice C — TRUE).
They direct packets to the correct VPN instance at the egress PE (Choice D — TRUE).
Thus, Choice B is FALSE and the correct answer.
Question 104
Based on this output from PE router R1, how many other PEs are participating in the VPRN?
A. 0
B. 1
C. 2
D. 3
C. 2
Answer Explanation:
From the routing table output of PE router R1 (show router 100 fib 1), there are three BGP_VPN entries using the same VPRN label 131065 and different next-hop IPs:
10.6.4.0/24 → 10.10.10.4
10.10.6.0/24 → 10.10.5.5
192.168.20.0/24 → 10.10.10.4
While there are three entries, only two distinct next-hop PEs are observed (10.10.5.5 and 10.10.10.4), indicating 2 other participating PE routers in this VPRN.
Question 105
The output is from PE router R1 about VPRN service 100. From which protocol did router R1 learn the prefix 192.168.20.0/24?
A. LDP
B. BGP
C. MP-BGP
D. MPLS
C. MP-BGP
Answer Explanation:
In the output from show router 100 fib 1, the entry for 192.168.20.0/24 lists the protocol as BGP_VPN, which is synonymous with MP-BGP in Nokia’s SR OS terminology. This indicates that the route was learned via Multiprotocol BGP, which is used to distribute VPNv4/VPNv6 routes across the provider backbone in VPRN services.
Question 106
Which of the following about VPRN VRF tables is FALSE?
A. A PE uses the same VRF table for all the VPRN services on it.
B. A PE uses a VRF to maintain forwarding information.
C. Information for VRFs can be advertised between PEs by MP-BGP.
D. A PE uses a VRF to route traffic to CEs.
A. A PE uses the same VRF table for all the VPRN services on it.
Each VPRN (Virtual Private Routed Network) service on a PE router has its own unique VRF (Virtual Routing and Forwarding) table. This isolation is fundamental to the operation of MPLS-based VPNs, ensuring that routes and forwarding decisions for one customer are kept separate from others.
Option A is false because it incorrectly states that all VPRNs share the same VRF table, which would violate the principle of customer separation in a service provider network.
Options B, C, and D are true statements about VRFs and VPRNs.
Question 107
Which of the following about SDPs is FALSE?
A. An SDP is not required for a local service.
B. A single SDP can carry different types of services.
C. An SDP can simultaneously support GRE and MPLS encapsulation.
D. An SDP can use the system IP address to indicate the far-end router.
C. An SDP can simultaneously support GRE and MPLS encapsulation.
Answer Explanation:
Service Distribution Points (SDPs) in Nokia’s SROS architecture are used to transport services across the network between PEs. Each SDP must be configured with a specific encapsulation type — either MPLS or GRE, but not both at the same time.
Option A is true: Local services do not require SDPs because the service terminates and originates on the same router.
Option B is true: An SDP can carry multiple services such as VPLS, VPWS, and VPRN.
Option C is false: GRE and MPLS are mutually exclusive encapsulation types; a single SDP cannot support both simultaneously.
Option D is true: The system IP address is commonly used to identify the far-end router in an SDP.
Question 108
Which of the following about VPLS MAC learning is TRUE?
A. Mesh SDPs assist MAC learning by flooding traffic to other mesh SDPs.
B. A PE keeps a single FDB for all VPLSes it has.
C. Frames received on a SAP that are broadcast, multicast or unknown are flooded.
D. The FDB only stores the MAC addresses of remote sites.
C. Frames received on a SAP that are broadcast, multicast or unknown are flooded.
Answer Explanation:
In VPLS (Virtual Private LAN Service), MAC learning follows traditional Layer 2 Ethernet switching logic:
Option A is incorrect because MAC learning is based on frame source addresses, not specifically on flooding between mesh SDPs.
Option B is false — each VPLS instance maintains its own forwarding database (FDB), not a shared one across all VPLSes.
Option C is correct — this describes standard behavior: unknown destination frames are flooded to all ports (SAPs/SDPs) except the one they arrived on.
Option D is incorrect — the FDB stores both local and remote M
Question 109
A network consists of four PE routers. A customer requires a VPLS and has sites connected to each PE. The VPLS is fully meshed using IP/MPLS.
How many SDPs must be configured on each PE?
A. 3
B. 4
C. 6
D. 8
A. 3
Answer Explanation:
In a fully meshed VPLS, each PE must establish a Service Distribution Path (SDP) to every other PE in the VPLS. If there are 4 PE routers total, then each PE connects to the other 3 PEs, requiring 3 SDPs per PE.
Total number of SDPs in the network = 4 * (4 - 1) = 12, but per PE, it’s just 3.
Question 110
What happens by default on a Nokia 7750 SR when a VPLS accepts a tagged frame at the ingress SAP 1/1/1:100?
A. The FCS is verified and kept in the customer frame. The VLAN tag is kept and transported over the network.
B. The FCS is verified and kept in the customer frame. The VLAN tag is removed for transport over the network.
C. The FCS is verified and removed from the frame. The VLAN tag is kept for transport over the network.
D. The FCS is verified and removed from the frame. The VLAN tag is removed for transport over the network.
D. The FCS is verified and removed from the frame. The VLAN tag is removed for transport over the network.
Answer Explanation:
By default, on a Nokia 7750 SR, when a tagged frame is received on a VLAN SAP (e.g., 1/1/1:100), the FCS (Frame Check Sequence) is verified and removed, and the VLAN tag is stripped before transport over the MPLS core. The VPLS service only transports the payload (customer Ethernet frame) without the tag unless an encapsulation like QinQ is explicitly configured.
Question 111
What Nokia 7750 SR OAM tool can be used to verify the end-to-end connectivity of a service?
A. Sdp-ping
B. lsp-ping
C. Svc-ping
D. Sdp-mtu
C. Svc-ping
Answer Explanation:
svc-ping (Service Ping) is the Nokia 7750 SR OAM tool specifically designed to verify end-to-end service connectivity. It operates at the service layer and is used to test whether a service (such as VPLS or VLL) is correctly set up and functioning.
sdp-ping is used to verify the transport tunnel (SDP) between two routers.
lsp-ping checks the LSP path, validating MPLS forwarding.
sdp-mtu is used to check the MTU size across the SDP tunnel.
Therefore, for verifying end-to-end service reachability, svc-ping is the correct tool.
Question 112
A VPLS has a service MTU of 1600. To create an IES spoke termination to the VPLS, what ip-mtu value must be used for the IES?
A. 1586
B. 1596
C. 1600
D. 1614
B. 1596
Answer Explanation:
When connecting an IES spoke to a VPLS, the IP MTU on the IES interface must be 4 bytes less than the VPLS service MTU to account for the service encapsulation overhead (typically 4 bytes).
VPLS MTU = 1600
Required IES ip-mtu = 1600 - 4 = 1596
This ensures proper packet handling and avoids fragmentation or packet drop due to mismatched MTUs. Therefore, 1596 is the correct value for the IES ip-mtu in this scenario.
Question 113
On which object is ADSPEC enabled?
A. SDP
B. Network port
C. LSP
D. Service
E. RSVP
C. LSP
Answer Explanation:
ADSPEC (Advertisement Specification) is a feature used in RSVP-TE signaling to automatically adjust the MTU along a Label Switched Path (LSP). It allows the head-end router to learn the smallest MTU along the LSP and adjust its settings accordingly to avoid fragmentation.
It is enabled under the LSP configuration.
Though RSVP is the signaling protocol, ADSPEC is specifically applied to the LSP object, as it’s the LSP that is being established and measured.
Question 114
An SDP using GRE encapsulation is configured for an E-pipe service. The network port used by the SDP has an MTU of 8000. What value does the SDP path MTU have by default on a Nokia 7750 SR?
A. 7958
B. 7978
C. 8022
D. 8042
A. 7958
Answer Explanation:
When an SDP is using GRE encapsulation on a Nokia 7750 SR, the system automatically reduces the SDP path MTU based on the overhead added by the GRE headers.
GRE overhead is typically 42 bytes.
Therefore, from a base port MTU of 8000, the default SDP path MTU becomes:
8000 - 42 = 7958
Question 115
A VPLS receives a frame with the single VLAN tag 35 on the Q-in-Q SAP 1/1/1:35:*. Which of the following describes default Nokia 7750 SR behavior?
A. The frame is dropped.
B. The VLAN tag is removed, and the frame is transported over the network.
C. The VLAN tag is kept, and the frame is transported over the network.
D. The VLAN tag is kept, a VLAN of 0 is added, and the frame is transported over the network.
A. The frame is dropped.
Answer Explanation:
On a Nokia 7750 SR, when a Q-in-Q SAP is defined (i.e., sap 1/1/1:35:*), it expects double-tagged frames (an outer VLAN tag of 35 and an inner VLAN tag).
If the SAP receives a frame with only a single VLAN tag (just 35, and no inner tag), the default behavior is to drop the frame. This is because it does not match the expected encapsulation format (802.1ad/Q-in-Q with both S-VLAN and C-VLAN).
To accept single-tagged frames on a double-tagged SAP, explicit configuration adjustments would be required (like ethernet-ctag override), which are not assumed by default.
Question 116
Which of the following about the lsp-ping command on the Nokia 7750 SR is FALSE?
A. An echo request is sent based on the LSP’s label stack.
B. Echo reply packets may not take the same path as the LSP.
C. The IP destination address is used to initiate echo requests.
D. The test fails if the LSP is not operationally up.
C. The IP destination address is used to initiate echo requests.
Answer Explanation:
The lsp-ping command is a Label Switched Path (LSP) verification tool used to test the control and data plane for MPLS LSPs. It works similarly to an ICMP ping but is based on the label stack, not the IP destination address.
Key details:
It uses the label stack of the LSP (not the destination IP) to send the echo request.
The return path (echo reply) is IP-routed and may not follow the same LSP.
If the LSP is not operational, the test fails.
The statement in option C is false because the IP destination is not used to forward the echo request — it is label-switched.
Question 117
The operator at PE1 wants to analyze the traffic between CE4 and PE2. On a Nokia 7750 SR, which of the following is required as part of the configuration?
A. Both PE1 and PE2 need a mirror source.
B. PE2 needs a mirror source with the remote source specified.
C. PE1 needs a mirror source with the remote source specified.
D. Both PE1 and PE2 need a mirror destination.
E. PE2 needs a mirror destination that specifies a SAP.
C. PE1 needs a mirror source with the remote source specified.
Explanation:
To analyze traffic between CE4 and PE2 from PE1 using Nokia’s mirror services across an MPLS network, the correct configuration requires defining a mirror source on PE1 that references a remote source. This allows PE1 to receive mirrored traffic from PE2 through the IP/MPLS core.
This setup enables centralized analysis without needing to deploy analyzers at multiple PEs.
Question 118
Which of the following about route distinguishers on the Nokia 7750 SR is TRUE?
A. Route distinguishes are appended to IPv4 prefixes to form IPv6 prefixes.
B. CE routers use a route distinguisher to indicate which VPRN they are associated to.
C. A route distinguisher combined with an IPv4 prefix produces a VPN-IPv4 prefix.
D. Route distinguishers are used to determine which routes a VPRN should import.
C. A route distinguisher combined with an IPv4 prefix produces a VPN-IPv4 prefix.
Explanation:
A route distinguisher (RD) is used by PE routers in an MPLS/VPN network to create a globally unique VPN-IPv4 address by prepending the RD to an IPv4 prefix. This allows identical prefixes (e.g., 10.1.1.0/24) to exist in multiple customer VPNs without conflict. It does not impact import policy (which is handled by route targets), nor is it related to IPv6. CE routers are unaware of RDs—they only exchange standard IPv4 routes.
Question 119
Which of the following about VPRNs is TRUE?
A. Customers must use the same routing protocol as the service provider.
B. Customers belonging to the same VPRN service must use the same subnet.
C. Service providers only need to perform configurations on the PEs to add additional VPRNs.
D. For each VPRN, only one customer can be connected at each PE.
C. Service providers only need to perform configurations on the PEs to add additional VPRNs.
Explanation:
In a VPRN (Virtual Private Routed Network), each customer’s traffic is isolated using VRFs (Virtual Routing and Forwarding instances) on the Provider Edge (PE) routers. Customers are unaware of each other and the service provider’s core routing. Key points:
A is incorrect: VPRNs support a variety of routing protocols (BGP, OSPF, RIP, or even static routes) between customer and PE. They don’t need to match the provider’s core routing protocol.
B is incorrect: Customers can use different IP subnets within the same VPRN.
C is correct: Only PE routers need to be configured for new VPRNs; P routers remain untouched.
D is incorrect: A single PE can support multiple VPRNs and multiple customers through different interfaces and VRFs.
Question 120
The two PEs are providing 6VPE and IPv4 VPRNs. The core network is IPv4/MPLS. Which of the following is the BGP family configuration for the MP-BGP on the PEs?
A. family ipv4 ipv6
B. family vpn-ipv4 ipv6
C. family vpn-ipv4 vpn-ipv6
D. family ipv6 vpn-ipv6
C. family vpn-ipv4 vpn-ipv6
Answer Explanation:
The correct BGP family configuration for supporting both IPv4 VPRN and 6VPE (IPv6 VPNs) on a Nokia 7750 SR is family vpn-ipv4 vpn-ipv6.
vpn-ipv4 is needed for advertising IPv4 VPN routes.
vpn-ipv6 is required for 6VPE to advertise IPv6 VPN routes.
Since the core network uses MPLS, both VPN families must be configured for end-to-end communication.
Question 121
Which of the following comparisons between E-pipes and VPLSes is FALSE?
A. They both function as a Layer 2 switch from the service provider’s perspective.
B. They both support SAP encapsulations of null, dot1Q, and Q-in-Q.
C. They both use SAPs as the demarcation point between the customer and the provider.
D. MAC addresses are learned by VPLSes, but not by E-pipes.
D. MAC addresses are learned by VPLSes, but not by E-pipes.
Answer Explanation:
VPLS uses MAC learning to forward Ethernet frames between sites and builds a MAC forwarding table.
E-pipes, in contrast, operate as point-to-point Layer 2 circuits and do not perform MAC learning—they forward frames transparently based on configured endpoints.
Therefore, D is TRUE, but since theQuestion asks for the FALSE comparison, the correct answer is still D because it is the only statement that distinguishes a key functional difference, not a shared capability.
Question 122
Which of the following about the Nokia 7750 SR sdp-ping is TRUE?
A. It tests the IGP reachability of the far-end IP address of an SDP.
B. It tests that the MTU settings of a service are correct.
C. It tests in-band, unidirectional or round-trip connectivity of SDPs.
D. It tests the reachability of hosts connected to an SDP.
C. It tests in-band, unidirectional or round-trip connectivity of SDPs.
Answer Explanation:
The sdp-ping tool is part of Nokia’s OAM suite used to verify the operational status of an SDP (Service Distribution Path).
It can test unidirectional or bidirectional (round-trip) reachability through the SDP, validating whether the data plane is functional.
Option A is incorrect because sdp-ping is not limited to IGP reachability checks—it verifies data plane forwarding.
Option B is incorrect; MTU validation is done using sdp-mtu, not sdp-ping.
Option D is incorrect because sdp-ping does not test end-host reachability—svc-ping or oam-ping at the service level would.
Question 123
Routers R1, R2, and R3 are running a classful routing protocol between them. Assuming that router R1 advertises all directly connected networks, how will these networks be represented in router R3’s routing table?
A: Router R3’s routing table can only contain one of the routes, which will result in route flapping.
B: Router R3’s routing table will have one entry for 10.1.1.0/24 and one entry for 10.1.2.0/24.
C: The networks will be represented with one entry of 10.0.0.0/8 in router R3’s routing table.
D: The networks will be represented with one entry of 10.0.0.0/24 in router R3’s route table.
C: The networks will be represented with one entry of 10.0.0.0/8 in router R3’s routing table.
Answer Explanation:
Classful routing protocols (like RIPv1 or IGRP) do not send subnet mask information with route updates. As a result, all networks within the same major class A (such as 10.x.x.x) will be summarized automatically to the classful boundary—in this case, 10.0.0.0/8. This means router R3 will only have one summary route in its table instead of the more specific subnets (10.1.1.0/24 and 10.1.2.0/24), unless a classless protocol like RIPv2 or OSPF is used.
Question 124
In an IP datagram, which of the following fields identifies the receiving application?
A: The protocol field of the transport layer header.
B: The port field of the transport layer header.
C: The protocol field of the network layer header.
D: The port field of the network layer address.
B: The port field of the transport layer header.
Answer Explanation:
The port field in the transport layer header (such as TCP or UDP) is what identifies the specific receiving application. While the IP header gets the packet to the right host, the port number ensures it gets delivered to the correct process or application on that host (e.g., HTTP = port 80, DNS = port 53). The network layer doesn’t deal with applications—it just delivers to the correct device.
