QoS, MPLS and Metro Ethernet Quiz

Which statement is _incorrect_ about MPLS?

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

• MPLS only allows 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 level 2 routing functionalities with level 3 switching functions

• If MPLS works over Ethernet it will use the TYPE field as the label

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

• If MPLS works over Ethernet, it will add the generic MPLS header to be able to label

Which of the following statements is _incorrect_?

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

• LSRs (Label Switch Routers) are internal label-based “switch-routers”

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

• The TTL field in an MPLS label has no correspondence with 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 in the same LSP (using EXP bits)

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

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

• In an L-LSP, the label can determine scheduling class, while EXP bits can determine 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 splitting available bandwidth in each link among different priorities

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

• DS-MPLS-TE necessarily places each QoS class on an entirely separate LSP

When implementing MPLS-VPNs, which statement is _incorrect_?

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

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

• The MPLS core (Provider routers, “P” routers) can itself run various IGP protocols (OSPF, IS-IS...)

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

Regarding packet forwarding in MPLS, which statement is _correct_?

• The actions performed by an LSR are: push, pop, or “no-stop”

• Penultimate Hop Popping (PHP) helps to reduce the label-processing load 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 in length

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

• It is the same RD for all VRFs in the entire 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 USA

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

• Many retail stores offer significant discounts on that day

• At La Salle it’s always summer, so no special day could be called “Black Friday”