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Q1. External EIGRP route exchange on routers R1 and R2 was failing because the routers had duplicate router IDs. You changed the eigrp router-id command on R1, but the problem persists. Which additional action must you take to enable the routers to exchange routes?
A. Change the corresponding loopback address.
B. Change the router ID on R2.
C. Reset the EIGRP neighbor relationship.
D. Clear the EIGRP process.
Answer: D
Q2. DRAG DROP
Drag and drop each step of the Unicast RPF process on the left into the correct order on the right.
Answer:
Q3. Which two statements about 802.1Q tunneling are true? (Choose two.)
A. It requires a system MTU of at least 1504 bytes.
B. The default configuration sends Cisco Discovery Protocol, STP, and VTP information.
C. Traffic that traverses the tunnel is encrypted.
D. It is supported on private VLAN ports.
E. MAC-based QoS and UDLD are supported on tunnel ports.
F. Its maximum allowable system MTU is 1546 bytes.
Answer: A,E
Q4. A service provider is deploying L2VPN LAN services in its MPLS cloud. Which statement is true regarding LDP signaling and autodiscovery?
A. LDP signaling requires that each PE is identified, and that an LDP session is active with its P neighbor for autodiscovery to take place.
B. LDP signaling requires that each P is identified, and that a targeted LDP session is active for autodiscovery to take place.
C. LDP signaling requires that each PE is identified, and that a targeted LDP session with a BGP route reflector is active for autodiscovery to take place.
D. LDP signaling requires that each PE is identified, and that a targeted LDP session is active for autodiscovery to take place.
Answer: D
Explanation:
LDP signaling requires that each PE is identified and a targeted LDP session is active for autodiscovery to take place. Although the configuration can be automated using NMS/OSS the overall scalability of the solution is poor as a PE must be associated with all other PEs for LDP discovery to work, which can lead to a large number of targeted LDP sessions (n2), which may be largely unused as not all VPLS will be associated with every PE. The security attributes of LDP are reasonably good, although additional configuration is required to prevent unauthorized sessions being set up. Although LDP can signal additional attributes, it requires additional configuration either from an NMS/OSS or static configuration.
Reference: http://www.cisco.com/en/US/products/hw/routers/ps368/products_white_paper09186a0080 1f6084.shtml
Q5. Which EIGRP packet types are sent as unicast packets?
A. hello, update, query
B. query, SIA query, reply
C. SIA query, reply, ACK
D. query, SIA query, SIA reply
Answer: C
Q6. When you enable the MPLS Multi-VRF feature, which two supported routing protocols can be used to exchange routing information between PE routers and CE routers? (Choose two.)
A. BGP
B. RIP
C. OSPF
D. EIGRP
E. IS-IS
Answer: A,B
Q7. Which statement describes what it means if a router has an OSPF priority set to 0?
A. A router with the OSPF priority set to 0 is one that can participate in the election of a DR. It has the highest priority.
B. A router with the OSPF priority set to 0 is one that cannot participate in the election of a DR, but it can become a BDR
C. A router with the OSPF priority set to 0 is one that cannot participate in the election of a DR. It can become neither a DR nor a BDR.
D. A router with the OSPF priority set to 0 is one that cannot participate in the election of a BDR, but it can become a DR
Answer: C
Q8. Which three options must be configured when deploying OSPFv3 for authentication? (Choose three.)
A. security parameter index
B. crypto map
C. authentication method
D. IPsec peer
E. encryption algorithm
F. encryption key
G. IPsec transform-set
H. authentication key
Answer: A,C,H
Q9. What is a reason for 6PE to use two MPLS labels in the data plane instead of one?
A. 6PE allows penultimate hop popping and has a requirement that all P routers do not have to be IPv6 aware.
B. 6PE does not allow penultimate hop popping.
C. It allows MPLS traffic engineering to work in a 6PE network.
D. It allows 6PE to work in an MPLS network where 6VPE is also deployed.
Answer: A
Explanation:
Q. Why does 6PE use two MPLS labels in the data plane?
A. 6PE uses two labels:
. The top label is the transport label, which is assigned hop-by-hop by the Label Distribution Protocol (LDP) or by MPLS traffic engineering (TE).
. The bottom label is the label assigned by the Border Gateway Protocol (BGP) and advertised by the internal BGP (iBGP) between the Provider Edge (PE) routers.
When the 6PE was released, a main requirement was that none of the MPLS core routers (the P routers) had to be IPv6-aware. That requirement drove the need for two labels in the data plane. There are two reasons why the 6PE needs both labels.
PHP Functionality
If only the transport label were used, and if penultimate hop popping (PHP) were used, the penultimate hop router (the P router) would need to understand IPv6.
With PHP, this penultimate hop router would need to remove the MPLS label and forward the packet as an IPv6 packet. This P router would need to know that the packet is IPv6 because the P router would need to use the correct Layer 2 encapsulation type for IPv6. (The encapsulation type is different for IPv6 and IPv4; for example, for Ethernet, the encapsulation type is 0x86DD for IPv6, while it is 0x0800 for IPv4.) If the penultimate hop router is not IPv6-capable, it would likely put the Layer 2 encapsulation type for IPv4 for the IPv6 packet. The egress PE router would then believe that the packet was IPv4. There is time-to-live (TTL) processing in both the IPv4 and IPv6 headers. In IPv6, the field is called Hop Limit. The IPv4 and IPv6 fields are at different locations in the headers. Also, the Header Checksum in the IPv4 header would also need to be changed; there is no Header Checksum field in IPv6. If the penultimate hop router is not IPv6-capable, it would cause the IPv6 packet to be malformed since the router expects to find the TTL field and Header Checksum field in the header. Because of these differences, the penultimate hop router would need to know it is an IPv6 packet. How would this router know that the packet is an IPv6 packet, since it did not assign a label to the IPv6 Forwarding Equivalence Class (FEC), and there is no encapsulation field in the MPLS header? It could scan for the first nibble after the label stack and determine that the packet is IPv6 if the value is 6. However, that implies that the penultimate hop router needs to be IPv6-capable. This scenario could work if the explicit null label is used (hence no PHP). However, the decision was to require PHP.
Load Balancing
Typical load balancing on a P router follows this process. The P router goes to the end of the label stack and determines if it is an IPv4 packet by looking at the first nibble after the label stack.
. If the nibble has a value of 4, the MPLS payload is an IPv4 packet, and the P router load balances by hashing the source and destination IPv4 addresses.
. If the P router is IPv6-capable and the value of the nibble is 6, the P router load balances by hashing the source and destination IPv6 addresses.
. If the P router is not IPv6-capable and the value of the nibble is not 4 (it could be 6 if the packet is an IPv6 packet), the P router determines it is not an IPv4 packet and makes the load balancing decision based on the bottom label. In the 6PE scenario, imagine there are two egress PE routers advertising one IPv6 prefix in BGP towards the ingress PE router. This IPv6 prefix would be advertised with two different labels in BGP. Hence, in the data plane, the bottom label would be either of the two labels. This would allow a P router to load balance on the bottom label on a per-flow basis. If 6PE used only the transport label to transport the 6PE packets through the MPLS core, the P routers would not be able to load balance these packets on a per-flow basis unless the P routers were IPv6-capable. If the P routers were IPv6-capable, they could use the source and destination IPv6 addresses in order to make a load balancing decision.
Reference: http://www.cisco.com/c/en/us/support/docs/multiprotocol-label-switching-mpls/mpls/116061-qa-6pe-00.html
Q10. Refer to the exhibit.
Which statement about this COS-DSCP mapping is true?
A. The expedited forwarding DSCP is mapped to COS 3.
B. COS 16 is mapped to DSCP 2.
C. The default COS is mapped to DSCP 32.
D. This mapping is the default COS-DSCP mapping on Cisco switches.
Answer: A
Explanation:
Here we see that COS 3 is mapped to DSCP 46, which is the Expedited forwarding class: The Expedited Forwarding (EF) model is used to provide resources to latency (delay) sensitive real-time, interactive traffic. The EF model uses one marking -- DSCP 46.