VPWS

Historically, solutions were based on leased FR or ATM (bandwidth, QoS) lines. True. False.

The IETF proposes two main solutions: 1. Virtual Private Wire Services (VPWS), pt-to-pt VPNs (FR/ATM/Ether.) 2. Virtual Private LAN Services (VPLS), mpt-to-mpt VPNs (Ethernet). True. False.

Customers can't keep their old links. True. False.

L2VPNs are more flexible than L3VPNs. True. False.

L2VPNs are independent of the L3 protocol. True. False.

Solution with CEs only (managed by customers)  Complex CE configuration if large number of sites and VPNs  May require purchase of equipment to support tunnels  It may be better to outsource the service to the SP. True. False.

IETF solutions are based on having CE devices and PE devices. True. False.

CEs only dialogue with local PEs. True. False.

In L2VPNs routing interaction occurs between the customer and service provider. In the L3VPNs, CEs and PEs perform peering. True. False.

In L2VPNs customers can run any type of L3 protocol between sites. True. False.

In L2VPNs using VPWS, multiple (logical) interfaces between each CE and its PE are required, one per remote CE that each CE needs to connect to. True. False.

In the forwarding plane, only LDP-based signaling use the same scheme for L2 frame encapsulation and transport across MPLS networks. True. False.

In the control plane, LDP-based signaling and BGP-based signaling differ significantly. True. False.

A PW emulates a single pt-to-pt connection to transport services over the SP packet-switched network (SPN), as an MPLS network. True. False.

In VPWS an MPLS-based L2VPN is composed of a collection of PWs. True. False.

IETF names PEs PW Emulation Edge-to-Edge (PWE3). True. False.

The term PW emphasizes that as far as possible the MPLS network should be invisible to the end customer, in such a way that the two CEs interconnected by the PWs appear to be directly connected back-to-back. True. False.

Ethernet. Mapping of traffic into a PW can be on a per-VLAN or on a per-port basis. True. False.

PWs can be supported not only by MPLS networks, but also by IP or Ethernet using tunnels. True. False.

In the per-port basis case, if the connection between a CE and its PE router contains multiple VLANs, each VLAN can be mapped to a different PW for transport to a different remote CE. True. False.

unstructured L1 TDM circuits and SONET/SDH, as well as structured bit streams, are supported by PWs. True. False.

TDM structures are universally delimited by placing an easily detectable periodic bit pattern, called the Frame Alignment Signal (FAS). True. False.

"structured TDM" refer to TDM with any level of structure imposed by an FAS. True. False.

structured TDM signifies a bit stream upon which no structure has been imposed, implying that all bits are available for user data. True. False.

Attachment Circuit (AC) is aphysical or virtual connection between CE and PE. True. False.

The IETF proposes two solutions for L2VPNs; 1. Virtual Private Wire Services (VPWS), pt-to-pt VPNs (FR/ATM/Ether.) 2. Virtual Private LAN Services (VPLS), mpt-to-mpt VPNs (Ethernet). True. False.

Virtual Private Wire Services (VPWS) is similar to ATM / FR services and uses mpt-to-mpt MPLS tunnels (LSPs). True. False.

Virtual Private LAN Services (VPLS) known as Transparent LAN Service (TLS) and uses pt-to-mpt MPLS tunnels. True. False.

In Virtual Private LAN Services (VPLS) service = The SPN is a LAN switch. True. False.

Forwarder. A PE subsystem that selects the PW to use in order to transmit a payload received on an AC. True. False.

Control plane. There are two alternatives: LDP-based signaling and BGP-based signaling. True. False.

For Ethernet, one PW may be mapped to: One VLAN and multiple ports (multiple VLANs mapped to a single PW). True. False.

Forwarding plane:L2 frames encapsulated and retransmitted over MPLS network. True. False.

GRE: Generic Routing Encapsulation is atunneling protocol developed by Cisco that can encapsulate a wide variety of L3 protocols inside virtual pt-to-pt or pt-mpt links over an IP network. True. False.

An MPLS network can't to set up PWs that carry the PDUs of different L2 protocols across the network. True. False.

We can distinguish three layers of L2 PDUs be encapsulated. : Tunnel header Demultiplexer field PW encapsulation. True. False.

Tunnel header: which contains the information needed to transport the PDU across the MPLS network;. True. False.

Demultiplexer field: is used to distinguish individual PW within a single tunnel; this field must be understood by the tunneling protocol as well;. True. False.

PW encapsulation: contains the information about the enclosed L2 PDU but is not necessary in order to properly emulate the corresponding L2 protocol. True. False.

Ingress PE removes: preamble and FCFs. True. False.

Two modes of transportation:  Tagged: 802.1Q tags are used for PW PDU processing.  Raw : May or may not contain tags, but are processed. True. False.

PDUs in the PW. Each field is associated with a layer of the PW reference model: 1. Tunnel Header: Info for PDU transport by SPN 2. PW Header: Identifies individual PWs in a tunnel (VLAN, VPN or outgoing connection). 3. Emulated VC Encapsulation: Info of the encapsulated PDU. In MPLS it is called Control Word. True. False.

Service Provider Network (SPN) and Provider Service Network (PSN) refers too the same concept. True. False.

Common characteristics in LDP-based signaling and BGP-based signaling solutions in control plane. When CE-A sends a packet to a remote CE-B, PE-A needs a means to know the PW label that remote PE-B expects. True. False.

Common characteristics in LDP-based signaling and BGP-based signaling solutions in control plane. PWs are bidirectional. If in one direction fails, forwarding is not allowed to occur in the opposite direction. True. False.

Differential characteristics in LDP-based signaling and BGP-based signaling solutions in control plane. Differ significantly in the way in which a PE knows the remote PE(s) with which it needs to set up PWs. True. False.

Differential characteristics In the original LDP-based scheme (martini PW), this information had to be manually configured on the PEs. True. False.

Differential characteristics:: The BGP scheme, has in-built autodiscovery properties, so this manual configuration is not required. True. False.

Differential characteristics:: The original LDP-based scheme was extended to use discovery information obtained by some means external to LDP (BGP). True. False.

LDP Signaling, Martini: Designed for the signaling of individual PW. The vision of a L2VPN does not exist. Each PW must be manually configured. True. False.

LDP Signaling, Martini: A targeted LDP session is created between each pair of PEs involved in L2 transport. True. False.

Targeted LDP session: A session between non-adjacent PEs, such that intermediate routers are not involved. True. False.

The same BGP sessions and same route reflectors can be used to support both services: L3VPN and L2VPN. True. False.

PEs learn through BGP about the existence of new CE (PE of new CE has and associate route) (autodiscovery property). True. False.

Difference between L2VPNs and L3VPNs: In L2VPN the PW label used to reach a particular CE depends on the CE that the packet originated from. Then, egress PE can determine the originating packet CE and forward it on the appropriate AC/receiving CE. True. False.

BGP Signaling : For each CE/AC attached to a PE, a CE ID is configured on the PE. This CE ID is unique within a given L2VPN. True. False.

BGP Signaling : Each local CE/AC is associated to a remote CE ID. True. False.

Label base and label-block offset is a compact method used by PEs to find the PW label to be used to reach a remote CE. True. False.

Each PE allocates autonomously a contiguous set of label values (blocks) per CE ID. True. False.

A PE advertises the value of the 2st label in the block (the label base) and the size of the block (the latter being the length field of the CSV sub-TLV). True. False.

BGP update message contains: Network Layer Reachability Information (NLRI). Contains: -Route Distinguisher. Disambiguates ‘routes’ to different VPNs (CE IDs must be repeated in different VPNs). -CE ID. -Label base and label-block offset. True. False.

Only label-block offset sent by PE-A are required by remote PE-B to calculate the PW label to usewhen sending traffic to a CE ID on a PE-A. True. False.

‘0’ - AC and tunnel (LSP) down. ‘1’ - AC or tunnel (LSP) up. True. False.

SP can create the L2VPN topology easily. True. False.

For hub-and-spoke topology. At a spoke PE, associate each spoke CE to the corresponding remote CE ID of the hub PE. True. False.

Alternative method. Exploiting BGP route filtering capability of extended communities. True. False.

A key property of the BGP-based scheme: PEs need config. of location of remote CEs (PEs they are attached to). True. False.

Using BGP if a new PE is added to the SP network and route reflectors are in use, only the new PE and the route reflectors of which it is a client need to be configured. True. False.

Extensions for L3VPNs can be used for L2VPN. For example, improved interprovider scenarios designed for L3VPN can be used by in L2VPN. True. False.

If a new CE site is added, only local PE needs configuration. True. False.

BGP-based scheme has explicit VPN awareness. True. False.

In LDP-based scheme Control plane sessions are Fully meshed. True. False.

In BGP-based scheme in Control plane sessions Can use route reflectors or confederations to avoid full mesh. True. False.

LDP-based scheme has In-built autodiscovery. True. False.

Interdomain capability in BGP-based scheme are difficult to achieve. True. False.

In BGP-based scheme Interdomain capability using schemes analogous to those for L3VPN. True. False.