642-611 - MPLS - Implementing Cisco MPLS Exam
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What is NOT true about an explicit LSP tunnel?
The tunnels cannot be included in the IGP shortest path calculation.
What is true about the following configuration? ip vrf green rd 100:10 route-target both 100:10 ip vrf blue rd 100:11 route-target both 100:11 ip vrf orange rd 100:12 route target both 100:10 route-target both 100:14
Site orange can talk to another site using an RT of 100:14.
Site blue cannot talk to site orange.
Site orange can talk to site green
What is true about overlay VPN's?
They are easy to implement.
Optimal routing requires a full mesh of VC's.
Which command would you use to display TDP hello timers?
show tag-switching tdp parameters
When should you disable redistribution of IPv4 routing updates between MP-BGP neighbors?
When the network is using OSPF or ISIS instead of I-BGP as the network IGP.
The VPN called my_vpn is operating on interface s0/0 of a PE-router. The CE-PE routing protocol is RIP. The MPLS backbone IGP is OSPF. How could you verify that the routes received from the remote CE-router are being redistributed into RIP?
Verify the routing table in the local CE-router.
Instead of using a routing protocol between the PE and CE routers it is possible to use static routes in some cases. What is true about static routes in MPLS VPN's?
The static routes are on a per VRF basis.
You must always specify the outgoing interface.
What is the purpose of the global configuration command, ip dhcp relay information option vpn?
enables the DHCP relay agent to insert the VPN suboptions to the BOOTP request
Cell interleave is an issue with ATM MPLS networks. Which of the following could result in this problem?
Per-platform label allocation is being used.
The MPLS VPN provider is using a separate Internet VPN to provide Internet access to its MPLS VPN customers. Currently, all of its customers are not able to access the Internet. The partial provider's CE-Internet router configuration is shown below. Based on the configuration, what could be the cause of the problem? ip route 0.0.0.0 0.0.0.0 10.1.1.1 ! router bgp 51001 network 0.0.0.0 neighbor 10.2.2.2 remote-as 51002 ! PE neighbor router neighbor 10.2.2.2 prefix-list test1 out neighbor 10.3.3.3 remote-as 51001 ! Another Internet router neighbor 10.3.3.3 prefix-list test2 out ! ip prefix-list test2 permit 0.0.0.0/0 ip prefix-list test1 permit 0.0.0.0/0 ge 1
The test2 prefix-list should be applied to the 10.2.2.2 neighbor and the test1 prefix-list should be applied to the 10.3.3.3 neighbor.
Which of the following is a valid LDP identifier for a router using per-platform operation?
What is the proper command to associate interface s0/0 with a VRF named my_vpn?
Router (config-if)# ip vrf forwarding my_vpn
Note: Please refer to the Case Study What routing protocol is used between the PE11 and CE11A routes?
Which are valid modes of MPLS operation?
What does the NEGOTIATED field in the output of the show tag-switching atm-tdp capability command indicate?
It indicates a set of options that both LDP peer devices have agreed to share on this interface.
Which three statements are true about route reflectors? (Choose three.)
If the route is learned from an EBGP peer by the route reflector, it is reflected to all IBGP and EBGP peers.
If the route is learned from a non-client IBGP peer by the route reflector, it is reflected to EBGP peers and clients only.
If the route is learned from a client IBGP peer by the route reflector, it is reflected to all EBGP peers, non-clients, and clients (except the originating client).
What is true about frame mode MPLS?
It uses per-platform label allocation.
What is penultimate hop popping?
A process run on the P-router that removes a label before forwarding the packet to the egress router.
How could you check for potential MTU size issues on the path taken by a PE-to-PE LSP?
Use the ping vrf command with packet size set to the largest MTU along the path and DF bit set from the local PE-router to ping the remote PE-router.
What does LDP use to find non adjacent neighbors?
Directed hello packets
A pair of MPLS routers, operating in the default frame-mode, are connected over two parallel links. Which of the following describes what will happen when they try to establish LDP sessions?
Only one LDP session will be established.
What is the name given to an IP address that is extended with an RD?
A VPNv4 address
Which three pieces of information are configured within the VRF configuration mode - Router(config-vrf#)? (Choose three)
MPLS VPN providers can be vulnerable to denial of service attacks by customers generating too many routes and depletting resources in the PE router. Which are valid methods of combating this possibility?
Limit the number of prefixes from a BGP neighbor using the neighbor maximum prefix command.
Limit the number of routes that can be imported into a VRF using the maximum route command.
What is a benefit of CEF switching?
CEF is less CPU intensive than fast switching is.
What does FEC stand for in respect to MPLS?
Forwarding equivalence class.
Only one route target can be associated with each route. True or false?
Which IOS command is used to display the entries from the ATM TDP tag-binding database?
show tag-switching atm-td.p bindings
In a central services topology, which routes do client VRFs contain?
Routes from the server site, but not from the client site.
What form of label distribution is used by RSVP-TE?
Which IOS table is built when CEF is enabled?
Which of the following is NOT a valid topology?
How are OSPF route attributes propagates across the MPLS VPN backbone? (Choose two)
OSPF cost or external metric is propagated in the BGP MED attribute.
OSPF area, route type, and metric type are propagated in an extended BGP community.
Which component of MPLS architecture is a simple label-based forwarding engine that is independent of the type of routing protocol or label exchange protocol?
When running basic MPLS in conjunction with VPNs, how many labels does each packet contain?
Each packet contains at least two labels. One label identifies the path to the egress router and one that identifies the VPN.
Which statement is true about implementing a hub-and-spoke overlay VPN?
If a dynamic routing protocol like RIP is used, split horizon must be disabled at the hub router, or point-to-point sub-interfaces must be used.
When using IP over ATM, which three statements are true? (Choose three)
A Layer 2 hub and spoke topology is usually used because it is easier to manager.
Layer 2 devices have no knowledge of Layer 3 routing information. Virtual circuits must be established.
Layer 2 topology may be different than the Layer 3 topology, resulting in suboptimal paths and link utilization.
Which command would you use to display the capabilities of LC-ATM peer LSR's?
show tag-switching atm-tdp capabilities
Which statement is true about the hardware requirements of MPLS?
MPLS is available on low end routers, built their use is limited because of the additional processing and memory requirements needed to build the LFIB.
The VPN named my_vpn is operating on interface s0/0 of a PE-router. The CE-PE routing protocol is RIP. The MPLS backbone IGP is OSPF. However, when you review the configuration for the PE-router, you find that BGP has been configured. What explains this configuration?
This router is configured improperly. E-BGP is the required routing protocol between PE and CE-routers.
What is true about a PE router?
It participates in customer routing protocols.
It runs provider backbone IGP.
It exchanges VPNv4 routes with other routers.
It has to run BGP.
Given the following MPLS configuration to enable frame-mode MPLS over ATM: interface atm 0/0.2 point-to-point pvc auto ip unnumbered loopback 0 tag-switching ip Which command is using incorrect syntax?
Which customer routing protocols will support MPLS VPN's?
The VPN named my_vpn is operating on interface s0/0 of a PE-router. The CE-PE routing protocol is BGP. The MPLS backbone IGP is OSPF. How should you verity routing information is being exchanged between the PE-routers that support this VPN?
On the local PE-router, you use the show ip bgp vpn4 command and verify that routes from the remote PE-router have been received.
What is the most typical use of an overlapping VPN?
Companies that use MPLS VPNs to implement both intranet and extranet services.
What is true of MPLS TE?
Every LSR needs additional information about links in the network, available resources, and constraints.
LSP tunnels are normally determined by IP routing protocols. What can be used to create an LSP tunnel via a specific path that is not the one that would be chosen by the IP routing protocol?
What are three drawbacks of a peer-to-peer VPN using a shared provider edge (PE) router? (Choose three)
All the customers have to share a common IP address space.
The shared PE router has to know all routes for all customers.
Packet filters are required on the PE routers.
When is the conditional label distribution used?
To save memory space by not advertising a label for the MPLS WAN links.
Which statement represents the overall impact of convergence in a frame-mode MPLS network when there is a failure on a link that an LSP is using?
Overall convergence is not affected because, by default, frame-mode MPLS uses liberal retention mode.