What frames will a dot1q null sap receive?

5. What is the default service MTU value for an Ethernet VPN service such as an epipe?

6. What is the relationship between the network port MTU and the SDP path MTU?

7. What are the two modes of operation supported on Alcatel-Lucent 7750 SR for an apipe service?

1. Which VPWS emulates a point-to-point TDM circuit?

Cpipe service emulates a point-to-point TDM circuit 2. What is the purpose of using VLAN tag?

VLAN tag is used to determine to which service the frame belongs

3. Verify whether the following statement is true or false: Multiple SAPs can be defined on a single port for different services.

True

4. What frames will a dot1q null sap receive?

A dot 1q null sap receives all untagged frames and all frames with a VLAN tag of 0 5. What is the default service MTU value for an Ethernet VPN service such as an epipe?

An Ethernet VPN service, such as an epipe service, has a default service MTU of 1514 bytes 6. What is the relationship between the network port MTU and the SDP path MTU?

Network port MTU >= SDP path MTU + transport tunnel encapsulation overhead

7. What are the two modes of operation supported on Alcatel-Lucent 7750 SR for an apipe service?

The two modes of operation supported on the Alcatel-Lucent 7750 SR for ATM apipes are the N:1 cell mode and AAL5 frame mode.

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Alcatel-Lucent Services Architecture

Module 3 — Introduction to Virtual Private LAN Service (VPLS)

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Module Objectives

After successfully completing this module, you will be able to:

 Explain the operation of Virtual Private LAN Service (VPLS)

 Explain how VPLS emulates a virtual Ethernet switch through its MAC learning and flooding behavior

 Configure and verify a VPLS

 Compare VPLS topologies (full mesh, hub and spoke, hierarchical VPLS, and spoke termination in a VPLS)

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Module 3 — Introduction to VPLS

Section 1 — VPLS Operation

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Section Objectives

After successfully completing this section, you will be able to:

 Define a VPLS and list its features

 Explain the similarities and differences between epipe and VPLS

 List the advantages of a VPLS from the perspective of both the customer and service provider

 Explain VPLS flooding behavior

 Identify the difference between mesh SDP and spoke SDP

 Describe the MAC learning process in VPLS

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VPLS Overview

 VPLS is an Ethernet service that connects multiple sites in a single switched domain over the provider-managed IP/MPLS network

 VPLS is essentially an enhancement of the VPWS

 Multiple VPLS services can be deployed using the same IP/MPLS core

A VPLS is a multipoint Layer 2 service that allows multiple customer sites to be connected in a single bridged domain contained within a provider-managed IP/MPLS network. Customer sites in the VPLS appear to be on the same LAN, even if the sites are geographically-dispersed. VPLS characteristics are described in RFC 4665 (Service Requirements for Layer 2 Provider-Provisioned Virtual Private Networks) and RFC 4762 (Virtual Private LAN Service Using LDP Signaling)

VPLS is essentially an enhancement of the Ethernet pseudowire service, or Virtual Private Wire Service (VPWS) to a multipoint service.

As discussed in Module 1, the advantages of a VPLS from the customer’s perspective are:

•To the customer it appears as if all sites are connected to a single switched Ethernet network.

•The VPLS is transparent to the customer’s data and higher layer protocols.

•The VPLS can operate over a single local site or at multiple, geographically-dispersed sites.

•The VPLS performs MAC learning so that frames are forwarded only across the required links in the network.

The advantages of a VPLS for the service provider are:

•Only the PE devices require configuration for the VPLS service.

•There is a clear demarcation of functionality between the service provider and customer networks.

•Scalability – the provider can support thousands of customers per router.

•Flexibility – many different services for many different customers can be provided over a single core IP/MPLS network.

•The service provider can apply QoS, billing, ingress/egress traffic shaping and policing on a per service basis

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VPLS vs. Epipe

Similarities:

 Encapsulation and transport mechanism

 The signaling of transport and service labels

 The SAP encapsulation types: null, dot1Q and Q-in-Q

 The treatment of customer data at the SAP Differences:

 A VPLS is a multipoint service; epipe is a point-to-point service

 The VPLS appears as a single switched LAN to the customer; the epipe appears as a direct Ethernet connection

 A VPLS performs MAC learning to build a forwarding database (FDB) containing the addresses of customer-attached devices

The similarities between an epipe and a VPLS are

•They both use the same encapsulation and transport mechanism: an MPLS or GRE encapsulated packet with an inner service label.

•The signaling of transport and service labels is the same: LDP or RSVP-TE for transport labels and T-LDP for service labels.

•The SAP encapsulation types of null, dot1Q and Q-in-Q are the same for a VPLS as for an epipe.

•The treatment of customer data at the SAP is the same in a VPLS as in an epipe The differences between an epipe and a VPLS service are:

•A VPLS is a multipoint service instead of the point-to-point service of an epipe.

•The VPLS appears as a single switched LAN to the customer, whereas the epipe appears as a direct Ethernet connection.

•A VPLS performs MAC (Media Access Control) learning to build a forwarding database (FDB) containing the addresses of customer-attached devices. The VPLS uses the FDB for intelligent forwarding of customer traffic over the IP/MPLS core network.

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VPLS: Customer Operation

 Customers maintain complete control over routing

 Adding new sites requires minimal reconfiguration at existing sites

VPLS 1 and VPLS 2 can use the same IP address ranges due to a VPN functionality provided with the VPLS service.

Note: since VPLS is a Layer 2 service, the customer site router interfaces that connect to the VPLS must belong to the same subnet. From the customer’s perspective, the routers are logically connected by a Layer 2 Ethernet switch.

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VPLS Label Signaling

 All PE routers in the VPLS are T-LDP peers and exchange labels for the service

 The VC-ID configured for the service must match among targeted LDP peers

 Customer frames are encapsulated with a service label and a transport label

 The VPLS instance on each PE router is often referred to as a virtual switch (VS)

PE 1->PE 2: For VC ID 101 Use VC-label 131071 PE 2->PE 1: For VC ID 101 Use VC-label 131069 PE 1->PE 3: For VC ID 101 Use VC-label 131071

PE 2->PE 3: For VC ID 101 Use VC-label 131069 PE 3->PE 1: For VC ID 101 Use VC-label 131070 PE 3->PE 2: For VC ID 101 Use VC-label 131070

For the transport of customer data, the VPLS acts as if it were a full mesh of epipes between all the PEs in the service.

Note: there is only a single T-LDP session required between two routers to signal service labels, regardless of the number of services that exist between them. For example, even if there were 100 VPLS or epipe services between PE 1 and PE 2, only a single T-LDP session would exist. The T-LDP session is used to negotiate service labels for all 100 services.

Note: if the VC IDs do not match point-to-point, the service label will not be present; therefore, the service will not be accessible on the remote router.

The VPLS instance on each PE router is often referred to as a virtual switch (VS) since it emulates the

In document Services Architecture v3.2 Student Guide Download (Page 174-183)