Preguntas sobre MPLS y Metro Ethernet

Which statement is incorrect about MPLS?

• MPLS leverages existing layer 2 technologies as protocols for the link layer

• MPLS only allows the transport of IP traffic

• The MPLS header is also called 'Shim Header'

• The MPLS header is positioned between layer 2 and the IP header

Which statement is true about MPLS?

• MPLS integrates and connects the routing functionalities of level 2 with the switching functions of level 3

• If MPLS operates over Ethernet, it will use the TYPE field as a label

• In MPLS, routing decisions are made at each hop in the same way as in IP

• If MPLS operates over Ethernet, it will add the generic MPLS header to enable labeling

Which of the following statements is incorrect?

• LERs (Label Edge Routers) are the edge nodes where packets are labeled or unlabeled

• LSRs (Label Switch Routers) are internal 'switch-routers' based on labels

• LSPs (Label Switched Paths) act like connection-oriented virtual circuits

• The TTL field in an MPLS label does not correspond to any Ethernet header field

Which corresponds to a label distribution protocol in MPLS?

• RIPv2

• RSVP

• OSPF

• LACP

Which of these statements is incorrect about E-LSP vs. L-LSP?

• An E-LSP allows prioritizing up to 8 different traffic classes within the same LSP (using EXP bits)

• In an L-LSP, we can define multiple drop priorities through EXP bits

• In an L-LSP, the entire PHB (scheduling + drop priority) is determined solely by the label field

• In an L-LSP, the label can determine the scheduling class, while the EXP bits can determine the drop priority

Regarding DS-MPLS-TE (DiffServ MPLS + Traffic Engineering), which statement is incorrect?

• DS-MPLS-TE is based on combining Traffic Engineering with QoS in MPLS

• DS-MPLS-TE allows dividing the available bandwidth on each link among different priorities

• DS-MPLS-TE can define different per-hop behaviors (PHB) for labeled traffic

• DS-MPLS-TE necessarily places each QoS class in a completely separate LSP

When implementing MPLS-VPNs, which statement is incorrect?

• Customers (CE devices) can run different routing protocols in their own networks

• MP-BGP (Multiprotocol BGP) is used to exchange VPNv4 routes across the MPLS core

• The MPLS core (Provider routers, 'P' routers) can run multiple IGP protocols (OSPF, IS-IS...)

• Only a single routing protocol can be used among all PE (Provider Edge) routers

Regarding packet forwarding in MPLS, which statement is correct?

• The actions performed by an LSR are: push, pop or 'do not stop'

• The 'Penultimate Hop Popping' (PHP) helps to reduce the processing load of labels on the egress LER

• The pop action is always performed only at the egress LER, never by a penultimate node

• LSRs do not perform push actions, only LERs do

Regarding the Router Distinguisher (RD) in MPLS VPNs, which statement is incorrect?

• It is 64 bits long

• It is added to a 32-bit IPv4 address to create a VPNv4 address, preventing IP overlap

• It is the same RD for all VRFs across the MPLS network

• Each VRF typically has its own RD to keep address spaces distinct

Which statement is incorrect about 'Black Friday'?

• It is celebrated after 'Thanksgiving Day' in the U.S.

• The term originated in Philadelphia to describe the heavy pedestrian/vehicle traffic

• Many retail stores offer significant discounts that day

• In La Salle, it is always summer, so no special day could be called 'Black Friday'