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TCOM 611
MPLS quiz
| Question | Answer | Hint | ||
|---|---|---|---|---|
| How many bytes are in a MPLS packet? | 4 Bytes | |||
| What layer is the MPLS packet header inserted in the IP packet? | Between layers 2 and 3 | Called the Shim Header | ||
| What label is used to signal Operation and Maintenance (OAM) used for failure detection, localization and performance monitoring? | OAM Alert – label 14 | |||
| When packets enter the network, the ingress router determines the __________ . | Forwarding Equivalence Class (FEC) | |||
| The ingress LER identifies the egress LER and sends it down the corresponding _______. | LSP Label Switch Path | |||
| True or False A data packet can have multiple MPLS labels | True | |||
| What are the two types of MPLS labels? | Transport and Inner | |||
| How are the transport labels learned by the MPLS enabled routers? | LDP or RSVP | |||
| MPLS EXP field is used for QoS, How many bits are in the EXP field? | 3 | only 8 class QoS | ||
| If your MPLS network is using more than 8 classes, How are additional bit acquired to gain additional classes? | Using the Most significant bits in the part of the label field (L-LSP) | |||
| What are the two MPLS modes? | Cell and Frame | |||
| In _________ mode, Routers exchange pure MPLS and IP packets. | Frame Mode | |||
| TRue or False: LDP exchanges messages between peers or also known as neighbors | True | |||
| LDP Neighbors are point-to-point and discovered via hello _________ messages 224.0.0.2 to a well known UDP port ___. | Multicast,646 | |||
| Remote LDP peers or peers that are not directly connected can also be discovered with unicast UDP _______ hellos | targeted | |||
| True or False: If pair of peers directly connected have more then one interface between each other there are multiple LDP sessions established. | False | |||
| LDP uses ___ for reliable delivery and session health | TCP | |||
| The ____ must converge for LDP to converge | IGP | |||
| What are the two label retention modes in MPLS? | liberal and conservative | |||
| label mapping advertisements for all routes may be received from all LDP peers. | Unsolicited Downstream label distribution mode | |||
| each LSR may advertise label mapping to its neighbors at any time it desires | Independent LSP Control | |||
| What protocols does MPLS TE leverage to distribute additional information about the network such as? Available bandwidth per interface by priority, Attribute flags per interface, Administrative weight per interface. | OSPF or IS-IS | |||
| What routing protocols support MPLS TE? | OSPF with LSA type 10and IS-IS with sub-TLV 250 and 251 | |||
| True or False: MPLS TE reserves bandwidth on a per tunnel basis. | True | |||
| MPLS TE tunnels have two types of priorities both using 0-7 with the lower number the being the best number. What are the 2 priority types? | setup,hold | |||
| True or False: MPLS TE tunnels can have a setup priority better than its hold priority. | false | |||
| The attribute flag of a link contains how many bits? | 32 | |||
| What metric are used to route MPLS TE traffic? | attributes, administrative weight, weight | |||
| When does MPLS TE flood information to all other routers? | links goes up or downLink’s configurations changes, when it’s time to periodically re-flood, link bandwidth changes significantly | |||
| RSVP is considered a ________ protocol and requires periodic refresh. | soft state | |||
| What is the default periodic flood time for MPLS TE? | 180 seconds | |||
| What method is used to calculate best path in MPLS TE? | constrained SPF | |||
| ____________allow for a tunnel to be built based on a series of explicitly defined next hops Include or exclude. | Explicit path-options | |||
| When using RSVP what device is responsible for controlling the LSP? | ingress LER | |||
| If there is an active tunnel up in the network and a better path becomes available the tunnel can be____________ to a new path. | re-optimized | |||
| What protocol provides end to end resource reservations? | RSVP | |||
| RSVP provides what 3 functions? | Path setup and maintenance Path teardown Path signaling | |||
| You want to ensure that your RSVP LSPs are following a particular path across the network. Which RSVP object ensures that your desire will be met? A. explicit route object B. record route object C. session object D. traffic specification object | A | |||
| Once the Path message reaches the destination it replies with a __________. A. ResvConfirm Message B. Hello Message C. Resv message D. Interserv Flowspec | C | |||
| A Resv is the acknowledgement that the reservation has been accepted end to end. What mechanism use by the egress tunnel router to signal headend tunnel? | Explicit route order | |||
| The Headend tunnel router sends a Path Message per tunnel to its neighbor every __ seconds? A. 5 B. 10 C. 30 D. 20 | C | |||
| What 2 messages are sent along the path to tear down the tunnel? | PathTer, and ResvTer | |||
| This MPLS TE optional mechanism allows LSPs to share bandwidth with itself. | Shared Explicit Reservation Style. | |||
| This feature of MPLS TE prevents the loss of data during tunnel re-optimization or a change in tunnel parameters. | make before break | |||
| When a MPLE TE tunnel needs to be built across multiple areas or an intra-area tunnel you must use explicate path with _______________ ERO. | Loose | This is used when the headend does not have routing past its own area and must rely on the ARB to complete the LSP tunnel to the egress LER. | ||
| What 3 methods are used to forward traffic down the MPLS tunnels? | static route, policy routing, and autoroute. | |||
| This routing feature of MPLS TE modifies the shortest path tree on the tunnel head-end LSR before the best routes are selected by the SPF. The path toward the tunnel tail-end LSR is replaced by a direct link created by the MPLS TE tunnel in the SPF tree. | autoroute | |||
| This mechanism can be configured on a per-LSP basis that monitor the interface rate and periodically resize the TE tunnel bandwidth. | Auto bandwidth | |||
| MPLS TE has the ability to mitigate packet loss associated with link and node failures using this predefined protection schemes know as ___________. | FRR | |||
| What are the 2 protection schemes that can be implemented with Fast Reroute FRR? | Path protection, Local protection | Local is more scalable | ||
| What are the advantages of Local protection? | Fast failure recovery,1:N scalability,Less consumption of network state | |||
| During a failure the PLR encapsulates the LSP onto the FRR tunnel to the___________. | Nhop | |||
| True or False: When you are using Node Protection of downstream nodes you automatically are protecting the links of the node. | true | |||
| What is the label mechanism is required to make node protection work properly? | ERO | |||
| What is the fast mechanism to determine a link failure with in the network? A. LDP Hellos B. IGP convergence C. RSVP Error detection D. Physical Layer | Physical Layer | |||
| When FRR is implemented and a failure occurs, a PathErr alerts the headend to ____________ the tunnel to find the most optimum path. | re-optimize | |||
| True or False: The IGP is just as effective as MPLS TE FRR in restoring service during a network failure in sub 50ms. | false | |||
| What is a new feature used to enhance the FRR capabilities in the IP/LDP to provide sub 50ms restoration of failures? | Loop Free Alternative | |||
| This most widely used MPLS QoS mechanism is highly scalable and parses data packets at the edge into classes on a per-hop queuing basis. | DifServ | |||
| How many classes does Differentiated Services Code Point (DSCP) support in the IP Packet? | 64 classes | |||
| How many classes does the MPLS EXP field support? | 8 classes | |||
| In this mode of MPLS QoS the packet classes are inferred based on the EXP field and maps a DSCP value to a EXP class. | EXP-Inferred LSP (E-LSP) | |||
| In this mode of MPLS QoS the packet classes are inferred from the label and the EXP value is ignored. | Label-Only-Inferred LSP (L-LSP) | |||
| An E-LSP is capable of carrying how many classes on a single LSP? | 8 Classes | |||
| In the Label Stacking process when going from IP to MPLS, what bits are copied to the EXP Field? | most significant bits | |||
| What are the 3 tunnel modes Tunnel modes that effect which PHB the resulting packets get in MPLS to MPLS or MPLS to IP? | Uniform, Short Pipe, Pipe | |||
| This tunnel mode propagates a copy of any changes made to the EXP value upward and downward. | Uniform Mode | |||
| This tunnel mode will copy the DSCP into EXP on imposition and does not modify the DSCP on exposition. | Short Pipe Mode | |||
| This model guarantees that there are no changes to the tunneled PHB marking through the LSP; even if an LSR along the path performs traffic conditioning and re-marks the traffic. | Pipe Mode | |||
| This extends MPLS traffic engineering to enable you to perform constraint-based routing of "guaranteed" traffic, which satisfies a more restrictive bandwidth constraint than that satisfied by CBR for regular traffic. The more restrictive bandwidth is term | DS-TE | |||
| The service provider network is a connection of point-to-point links or virtual circuits (VCs). Routing within the customer network is transparent to the service provider network, and routing protocols run directly between customer routers. | Overlay model | |||
| Both provider and customer network use the same network protocol and all the customer routes are carried within the core network (service provider network). | Peer to Peer model | |||
| What are the building blocks of the MPLS Layer 3 VPN? | MPLS LDP or RSVP, Virtual Routing and Forwarding (VRF), Route Distinguisher (RD), Route Targets (RT), MP-BGP | |||
| A technology that allows multiple instances of a routing table to co-exist within the same router at the same time and enables different customers to use overlapping addresses. | VRF | |||
| 8-octet field prefixed to the customer's Internet Protocol address (IPv4) used by the edge routers to identify which VPN a packet belongs to. | Route Distinguisher | |||
| MPLS based VPNs use____________ protocol to pass routes between PE devices. | BGP | |||
| An 8 byte field used to define the values that should be matched against to decide whether a route is eligible to be imported into this VRF. | Route Target | |||
| This extension called VPNv4 added to this protocol provides MPLS layer 3 route propagation. | MP-BGP | |||
| What protocols supported between PE to CE routers? | Static,RIPv2,OSPF,EIGRP,IS-IS,eBGP | |||
| An __________ can be understood as an intranet mapped onto the public Internet or some other transmission system not accessible to the general public. | Extranet | |||
| How does MPLS Layer 3 VPN’s provide for Extranet support using the? | VRF table import/export | |||
| A full mesh of MP-iBGP sessions is required between the PE routers, This creates scaling issues, but this issue can be alleviated somewhat by using __________ routers. | Route Reflectors | |||
| Many customers require Internet service at some or all of their locations, please list the 3 designs that could provide this connectivity? | Using Central Firewall,Using a separate BGP session Internet routing, Central Internet provider site with a default router. | |||
| This option allows routers to identify the site from which each route originated, the following Routing protocols are supported: OSPF, EIGRP, BGP. | Site of Origin | |||
| When redistributing MP-BGP VPNv4 routes into EIGRP that has multiple connections to the same network, what BGP attribute must be set to prevent loopbacks? | Site of Origin extended community with a route-map | |||
| What is the name of the RFC which gives MPLS providers the ability to efficiently transmit customer multicast traffic. | mVPN | |||
| These trees are built inside the providers and connected using GRE tunnels to distribute content to many users. | Multicast Distribution Tree | |||
| What are the 2 types of Multicast Distribution Tree’s? | Default MDT Groups, Data MDT Group | |||
| What label is used to indicate: Egress LSR request upstream LSR to perform pop | Implicit NULL – label 3 | |||
| What are the 3 MPLS Label operations the MPLS routers must perform? | PUSH,SWAP,POP | |||
| What label is used to indicate: Egress LSR request upstream LSR to perform swap? | Explicit NULL – label 0 |
Created by:
maa4116
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