LAYER 2 VPN ARCHITECTURES EBOOK
A complete guide to understanding, designing, and deploying Layer 2 VPN technologies and pseudowire emulation applications. Evaluate market drivers for . LAYER 2 VPN ARCHITECTURES AND OPERATION J. M. Arco, A. García, J. A. Carral, A. Paricio Departamento de Automática Universidad de Alcalá Escuela. Layer 2 VPN architectures (author Anthony Chan, Carlos Pignataro, Dmitry Bokotey, Wei Luo) mobiles ebook. Anthony Chan, Carlos Pignataro, Dmitry Bokotey.
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Tags are preserved. The MAC network. This has a limitation, there are only address table of a provider ingress node, associate all the different services instances or clients.
Other solution can reduces the MAC address table size. Both of the two independent of the Q-tag schemes used and can be approaches are not standard . MiM also enables QoS capabilities.
MiM Figure 3. Label the same MAC address. The ingress node insert two C-Payload additional fields source and destination MAC addresses of the provider edge nodes figure 4.
Figure 5. MiM provides up to 16 million service instances. Flat VPLS network.
The being investigated by the standardization bodies and are key of VPLS technology was the definition of Ethernet applicable to a bridged provider network . These over MPLS using draft-martini encapsulation  that technologies can be also combined into an hierarchical describes a mechanism whereby Ethernet can be network to improved the providers networks performance encapsulated within a MPLS LSP for transport. VC label Encapsulation fields Lasserre propose an easer technique known as split Tunnel label Tunnel label horizon forwarding.
Figure 6. MPLS layer 2 encapsulation Discovery and signaling mechanisms The tunnel label is inserted at the top of the stack, which is then used by the MPLS network to reach the egress Autodiscovery allows PE devices to automatically node.
The VC label is introduced at the bottom of the discover other PE devices that belong to the same VPLS stack is used by the egress node to deliver the frame to the service instance. Lasserre does not propose any specific destination network. Some of the mechanisms that can be used are: QoS technologies, the VC label can be seen as the Q-tag and profiles. Not all the PWs will have the same characteristics between each PE associated with a mechanisms.
Layer 2 VPN architectures pdf | Assoruwhicov
One of the most important to set up PW and encapsulate packets, and propose LDP draft is the draft-ietf-l2vpn-vpls-ldp Security is also an important issue. Lasserre does not give edge network, the first one is an IEEE bridged network any recommendation about security. This is a 3. The adjacencies with its associated N-PEs.
MPLS network, figure When devices introductory case and comprehensive design scenarios. ThisPE book learn about the emulated services from each other, they automatically pseudowires assists readers looking to meet those requirements byestablish explaining the among them accordingly.
Ideally, an auto-discovery mechanism has the minimal amount history and implementation details of the two technologies available fromof manual involvement pseudowire setup. The structure of thistobook is 3 focused on first introducing the reader to Layer 2 VPN benefits and implementation requirements and Pseudowire setupcomparing often requires protocols or extending existing protocols themcreating to thosenew of Layer 3 based VPNs, such as MPLS, then to signal pseudowireprogressively information.
Whenever a major new technology emerges, many companies and organizations get involved Publisher: Cisco Press in the standardization process and10,try to push the proposals that are favorable to their Pub Date: March business interests.
Because the majority of vendor and operator support and activity of pseudowire emulation happen in the IETF, this section focuses on the standard process of the IETF. The technical of the by topicby into severalyour areas, network architecture such as internet, routing, and transport.
Under each technical area are several working groups where the actual work is done. Gain from the first book to address Layer 2 VPN application utilizing both L2TP protocols Working groups form as theATOM resultand of popular interests of solving a particular problem from the networking community and disband when the problem is resolved.
Sometimes the charter of a that arises allow large customers to enhance working group changesReview when astrategies new problem or theenterprise original problem evolves.
That is, the goal is to encapsulate service-specific PDUs received on one 2 VPNthem Architectures introduces readers to Layer 2 Virtual and Private ingress portLayer and carry across a tunnel, and to emulate the behaviors Network VPN concepts, and describes Layer 2 VPN techniques via characteristics of the service as closely as possible.
The two most debated proposals on introductory case studies and comprehensive design scenarios.
This bookBOF pseudowire emulation"draft-martini" and "draft-kompella"first surfaced in this PWE3 assists lookinglater to meet those requirements by explaining the session. Both draftsreaders are discussed in this chapter. Layer 2 Tunneling Protocol working group This working group is responsible for protocol extensions that support carrying multiple Layer 2 services over IP networks.
They were known as "draft-martini" and "draft-kompella. Both drafts addressed the question of how to achieve pseudowire emulation over packet-based networks, but the solutions that each proposed were vastly different. The two drafts were focused on achieving emulation over MPLS-based packet networks, and each Layerpseudowire 2 VPN Architectures solution had its advantages and disadvantages.
The terms draft-martini and draft-kompella have become synonyms for the two different network architectures that they represent. The actual drafts do not exist in IETF anymore, but the ideas behind them are making their ways toward becoming standards. However, these informal names aretostill widelyenhanced used in the networking Master the world of Layer 2 VPNs provide services and enjoy community to identify the doctrine of each vendor implementation.
This section lists productivity gains the pros and cons of each architecture and does not intend to advertise one method over the other.
Gain from the first book to address Layer 2 VPN application utilizing The most significant characteristic of draft-martini is its simplicity and straightforwardness.
It also specifiestothe Review strategies that allow large enterprise customers enhance encapsulation methodstheir for each Layer 2 service. The For a majority of Service significant portion of their revenues architecture is concerned with creating andProviders, managingaindividual point-to-point pseudowires, are still derived from data and voice services based on legacy transport which have no correlation to one another.
Because the baseline LDP not lucrative readily have the backbone new carriers would like todoes sell the Layer 2 necessary protocol element services for pseudowire signaling, draft3 defines a pseudowire forisLDP. The solution inextension these cases a A pseudowire is considered established when theLayer peering PE devices exchange information technology that would allow 2 transport over a Layer label 3 for the pseudowire.
Layer 2 VPN Architectures introduces readers to Layer 2 Virtual Private Network operators can provision pseudowires using the architecture that is defined Network VPN concepts, andby describes Layer 2 VPN techniques via in draftmartini manually introductory or through some of network management system. It is much like case sort studies and comprehensive design scenarios.
To a certain degree, it shares some characteristics of Layer 3 dynamic routing. Unlike draft-martini, it involves complex signaling procedures and algorithms, and the provisioning scheme, which is somewhat tricky, works better with some Layer 2.
AsArchitectures shown earlier in Figure , a pseudowire is needed to connect two CE devices that attach to two different PECarlos devices. This can become a dauntingly labor-intensive task for. The draft attempts to solve the scaling problem by over-provisioning the Contents number Indexof attachment circuits needed for current CE devices so that the existing CE and its PE devices do not need to be reconfigured when adding a new CE to a VPN. The basic premise for over-provisioning is that the attachment circuits between CE and PE devices are relatively cheap.
This is also known as the CE range. By such an arrangement, each CE can derive which attachment circuit Reduce costs PE and the reachwith of your by unifying your connects to which remote CE. Each is extend then configured the services VPNs in which it participates.
The smallest value in this label range is their service offerings while maintaining routing control called the label base. For a majority of Service Providers, significant portion of their Even though some PE devices might not be part of the VPN, they can receive and keep this are still derived from data and voice services based on legacy transport information just in case a CE that is connected to the PE joins the VPN in the future.
Because technologies. Ideally, carriers existing signaling, the draft defines a pseudowire extension for BGP. The solution in these cases is a CE device a local matter. That is, whenever a new CE device is added, only the CE and the PE technology that would allow Layer 2 transport over a Layer 3 to which it is attached need to be configured. Remote CE and PE devices do not need infrastructure. This book devices. In the latter case in which the comparing them to those of Layer 3 based VPNs, such as MPLS, then cost of individual attachment circuits is expensive, over-provisioning becomes impractical.
Also, progressively covering each currently available solution in greater detail. If a Layer 2 VPN consists only of sparse point-to-point connections, advertising the information of a CE to all other PE devices and keeping it on these PE devices waste network resources because such information is only interesting to a single remote PE.
Not exhaustively, Table compares the most noticeable characteristics of the two Layer 2 VPN architectures that are defined by draft-martini and draft-kompella. Table Gain from the first book to address Layer 2 VPN application utilizing Standardization Proceed to PWE3 working Obsolete bothdocument ATOM andstatus L2TP protocols progress group Review strategies that allow large enterprise customers to enhance their service offerings while maintaining routing control Even though draft-martini has made a lot of progress in standardization and deployment, its primitivenesssuchFor as athe lack of of support inProviders, Layer 2 VPN autodiscoveryis New majority Service a significant portionrecognized.
Ideally, carriers with existing legacy Layer 2 and Layer 3 networks would like to move toward a single backbone while new carriers would like to sell the lucrative Layer 2 services their existing Layer 3 cores. The Layer 2 VPN architectures on pseudowire emulation generally define the procedures for setting up individual pseudowires and encapsulation methods for different Layer 2 services.
This book VPWS is directly derived from pseudowire emulation. Instead of acting as a point-to-point cross-connect between the attachment circuit and pseudowire, a VPLS PE functions as an Ethernet bridge. If it finds a match, it forwards the frame to the output interface that is specified in the bridging table.
Otherwise, it learns and stores the source MAC address in the bridging table, and it floods the Ethernet frame to all output interfaces in the same broadcast domain.
In this respect, VPLS resembles. Pseudowire emulation is an emerging Publisher: Cisco Press networking technology that aims at transitioning traditional Layer 2 services much PSNs for operating cost reduction and new Pub Date: Contents Within the network reference model, PE devices are the key components that provide Index pseudowire emulation services. A PE device consists of the control plane that establishes and. Master world of Layer 2 VPNs to provide enhanced services andexplained enjoy This chapter outlined thethe pseudowire protocol and encapsulation layering.
It further productivity gains the various stages of processing in a pseudowire emulation system, such as signaling, native service, pseudowire encapsulation, and tunnel encapsulation. Learndeployment about Layerof2pseudowire Virtual Private Networks Even with the fast-growing emulation, the VPNs standardization process is an ongoing effort.
The IETF and its working groups are the most active and widely respected Reduce that costsdevelop and extend the reach ofsolutions your services by unifyingemulation your standardization organizations frameworks and for pseudowire network architecture and Layer 2 VPN technology in general. This chapter compared the most debated proposals on pseudowire emulation architectures and highlighted other Layer 2 VPN architectures that are Gain from the first book to address Layer 2 VPN application utilizing built on top of pseudowire emulation.
Chapter 3. In the past few years, industry and Internet Engineering significant progress has been made both in designing the Layer 2 VPN protocol specifications and realizing such innovations in a suite of new products. Reduce costs and extend the reach of your services by unifying your A handful of network equipment vendors have developed products that support various levels network architecture of pseudowire emulation.
The deployment of pseudowire emulation has started growing in the service provider space. Review strategies that allow large enterprise customers to enhance their service offerings while maintaining routing control AToM. For a majority of Service Providers, a significant portion of their revenues are still derived from data and voice services based on legacy transport L2TPv3 technologies.
Ideally, with existing To understand the functionalities characteristics pertaining tocarriers these products, you need to legacyproperties Layer 2 and Layer 3 networks like to or move toward a single first know the inherent and operations of thewould traditional, legacy, Layer 2 VPNs.
Press based on the following Pubtechnologies: Frame Relay and ATM are the costarchitecture effective alternatives to the expensive and dedicated leased line service. Service providers can offer these lower cost services to the their customers becauseLayer the Frame and ATM network Gain from first book to address 2 VPNRelay application utilizing infrastructure can be shared among many both ATOM and L2TPcustomers protocols while maintaining a comparable level of functionality and guarantee as the leased line service.
Frame Relay and ATM also provide link Reviewcustomers strategieslike that allow large enterprise separations among different the leased line service. Frame and are still purchase derived from data and information voice services based legacy transport ATM customers typically a committed rate CIR on that allows traffic burst technologies.
CIR3 is the guaranteed minimal bandwidth customers, they have some drawbacks. Ideally, carriers existing network is congested. With the bandwidth oversubscription feature, Framewith Relay and ATM legacy 2 and than Layerthe 3 networks would like to move toward a single customers can use moreLayer bandwidth CIR during traffic bursts as long as the network backbone while new carriers would like tocircuit sell the lucrative Layer 2 has available capacity.
Frame Relay and ATM also provide multiplexing capability that services over circuits their existing cores. The solution these cases a be carries multiple logic or virtual over aLayer single3physical link, and theinvirtual circuitsiscan technology that would allow Layer 2 transport over a Layer 3 used to connect to different remote sites. TheyLayer are a2huge revenue-generating source for service providers. This book providers often have to maintain separate networks for Layer 2 and Layer 3 traffic.
The structure of this book is focused on first introducing the Figure The links that are Reduce costs and extend the reach of your services by unifying your depicted in the diagram represent logical connections. The structure of this book is focused on first introducing the Data Link Switching reader to Layer 2 VPN benefits and implementation requirements and comparing them to those of Layer 3 based VPNs, such as MPLS, then DLSw provides a method to transport legacy and nonroutable protocolssuch as Systems progressively covering each currently available solution in greater detail.
VPDNs are commonly used in wholesale remote-access environments. Without VPDNs, enterprises have to purchase and manage dial-up lines and network access servers for their employees to access internal enterprise resources remotely. The operating and upgrading cost Layer 2 VPN Architectures can be prohibitively expensive for small and medium-sized companies.
Press their remote access infrastructures and operations to wholesale service providers. The service Pub Date: March 10, providers offer remote access facilities to enterprise remote users from the nearest point of presence PoP and backhaul the remote access ISBN: The enterprises only need to manage a small connections.
When the total Master theservice world of Layer 2 VPNs to provide enhanced services and enjoy number of users increases, providers can add or upgrade their remote access network productivity gains because all users benefits from it. Figure depicts a capacity in a more economic fashion VPDN network topology. Gain from the first book to address Layer 2 VPN application utilizing [Viewprotocols full size image] both ATOM and L2TP Review strategies that allow large enterprise customers to enhance their service offerings while maintaining routing control For a majority of Service Providers, a significant portion of their revenues are still derived from data and voice services based on legacy transport technologies.
This book assists readers looking to meet those requirements by explaining the Layer 2 Tunnel Protocol Version 2 L2TPv2 history and implementation details of the two technologies available from the Cisco suite: However, because PPP encapsulate cores. The following is a brief description of how VPDN protocols operate: The network access server receives the connection request from the remote user. March 10, server 3. Contents Index. After the remote user is authenticated, an authorization process determines whether the user should be locally terminated or tunneled to a home gateway.
If the remote user needs to be tunneled to a remote home gateway, one of the VPDN Master the world of Layer 2 VPNs to provide enhanced services and enjoy protocols establishes a tunnel between the network access server and the home gateway, productivity gains and an optional authentication step can validate the identification of the tunnel endpoints.
Reduce costs and extend the reach of your services by unifying your 7. The home gateway authenticates the remote user carried in the VPDN session. Upon network architecture successful authentication, the home gateway terminates the PPP connection and grants predefined network access to the Gain from privileges the first book to remote addressuser.
Now PPP frames can pass between the remote user and the home gateway. Review strategies that allow large enterprise customers to enhance For detailed configuration andofferings examples of the legacy Layer 2 VPNs, refer to Cisco. Ideally, carriers with existing Table Layer Legacy VPN Comparison legacy 2 andLayer Layer 32networks would like to move toward a single backbone while new carriers would like to sell the lucrative Layer 2 Legacy Layer services over their existing Layer 3 cores.
Cisco Press service provider space, where Pub especially Date: March 10, network infrastructures are based on ATM. In classic connections. This converged MPLS infrastructure can provide bothenhanced Layer 2 and Layerand 3 services productivity that previously had to rely on gains separate networks. Besides providing the end-toReduce costs and extend the reach of your services by unifying your end connectivity of the same Layer 2 protocol, AToM is capable of interconnecting disparate network architecture Layer 2 protocols through Layer 2 interworking.
AToM derives from a series of efforts by service providers and network equipment vendors in an attempt to minimize the impact to Gain from the first book to address Layer 2 VPN application utilizing existing Layer 2 VPN services and create new service offerings with MPLS-enabled networks.
Ideally, carriers with existing to a VPDN session. Because an MPLS technology that would allow Layer 2 transport over a Layer 3 LSP is inherently unidirectional, to have bidirectional connectivity, a pseudowire is formed by infrastructure.
This bookYou establish a targeted LDP session by sending unicast hello packets rather than multicast assists readers looking to meet those requirements by explaining the hello packets during the LDP discovery phase. AToM Components progressively covering eachNetwork currently available solution in greater detail.
Master the world of Layer 2 VPNs to provide enhanced services and enjoy Supported Layer 2 protocols productivity gains Decision factors whether to use AToM in your network, such as installation base, advanced features, interoperability, and complexity.
Creating such hierarchies allows aggregation multiplexing, which their service offerings while maintaining routing control improve scalability. It also simplifies the operations on the transit routers, which make forwarding decisions based on the topmost label in the label stack. For a majority of Service Providers, a significant portion of their revenues stillinderived and voice services based on legacytotransport The semantics of are labels a label from stackdata might vary from one MPLS application another.
For technologies. Ideally, carriers with existing engineered path, and the bottom label represents the original Interior Gateway Protocol IGP legacy Layer 2 top andlabel Layerin3the networks would like to move a single path.
The bottom a specific orcores. Figure shows the overview of an AToM packet. The bottom label is usually known as the VC label Review or the pseudowire label.
Thelarge optional control customers word is nottopart of the strategies that allow enterprise enhance MPLS label stack, but pseudowire encapsulation. Ideally, carriers with existing legacy Layer 2 and Layer 3 networks would like to move toward a single The semantics of labelswhile in a label stack might belike different the previous backbone new carriers would to sell from the lucrative Layer 2 description when multiple MPLSexisting applications deployed integrated in the same services over their Layerare 3 cores.
Theand solution in these cases is a MPLS network. The structure of this focused to onafirst introducing theof the overall operation reader cost structure. Only PE routers need to maintain and manage the pseudowire labels for the virtual connections.
The pseudowire labels are at the bottom of the label stack, so they are not visible to the transit routers, also known as the Provider P routers. The P routers forward packets using the top label and are unaware of the existence of pseudowires. In such a way, the core network is spared from managing and maintaining forwarding information for each pseudowire. In other words, CE routers are the only Publisher: March 10, participate in PPP protocol exchange.
Bridging protocol support varies depending on the deployment model. To Frame Relay customers, the migration in the service provider network For is completely The Frame Relay header is removed the ingress a majority transparent.
The flags in the Frame Relay headerssuch as are still derived from data and voice services based on legacy transport backward explicittechnologies. These modes determine the granularity of how ATM packets and cells should be classified and mapped to pseudowires.
Network operation complexity Publisher: March 10, The next sections describe how each of these factors can help you determine whether AToM is feasible for your networking environment. Existing Network Installation Base For those service providers that have separate parallel networks for Layer 2 and Layer 3 Master thenetwork world ofisLayer 2 VPNs to provide enhanced services and onto enjoya services, an MPLS-enabled a natural candidate for converging all services productivity gains single network infrastructure.
Such a migration allows the service providers to expand their network capacity and service portfolios Reduceon costs and extend the reach of your services by unifying your and protect their investment the existing network infrastructure. Transitioning to the network architecture packet-based AToM pseudowire emulation has minimal impact to the existing Layer 2 VPN services. Advanced Network Review Services strategies that allow large enterprise customers to enhance their service offerings while maintaining routing control Besides the basic MPLS features such as routing optimization and network consolidation, AToM For a majority of Service Providers,network a significant portion of as their revenues can leverage advanced MPLS features for enhanced services, such MPLS traffic are still derived from data and voice services based on legacy transport engineering, QoS guarantee, and fast rerouting.
Ideally, carriers withhas existing The efficiency with which a service provider its network infrastructure a significant legacy Layerof2its and Layer 3 The networks would like touse move toward aresources, single impact on the cost structure business.
The solution in these a service offering. Traffic engineering at solving problem that some parts cases of the is network technology that would allow Layer 2MPLS transport Layerengineering 3 are highly congested while others are underutilized.
Constraintbased routing is essentially a set of algorithms designed to find an optimal path with given Layerconfined 2 VPN Architectures introduces readers to The Layer 2 Virtual Private routing metrics while to the pre-established constraints.
This book introductory studiesisand comprehensive design scenarios. This book go into details about why plaincase IP routing insufficient for traffic engineering. The structure of this book is focused on first introducing the Note reader to Layer 2 VPN benefits and implementation requirements and comparing to those Layer 3 based VPNs, such MPLS, thento If you are interested in them learning more of about traffic engineering, youasmight want progressively read the following books: Cisco Press, Technology and Applications by Bruce S.
Davie and Yakov Rekhter: Morgan Kaufmann Publishers, MPLS traffic engineering helps redirect trafficincluding Layer 2 trafficto less congested parts of the network. Layer 2 services typically come with service-level agreements SLA.
An SLA is a Publisher: Ciscoprovider Press service guarantee that a service agrees to offer to its customer on availability, Pub Date: March 10, and so on. The guarantee to enforce SLAs. For instance, an SLA with a higher premium might Pages: It allocates the necessary network resources, such as buffer space and link bandwidth, along the specific path that is established through traffic engineering.
With hop-by-hop, destination-based plain IP routing, the network convergence costs and extend the reach services by unifying your time is usually secondsReduce upon network failure, which resultsofinyour packet loss before the network network architecture converges. To reduce packet loss during routing transitions, MPLS fast rerouting constructs a protection LSP in advance for a given link by explicitly establishing an alternate path that Gain fromlink.
For a majority of Service Providers, a significant portion of their revenues A rapidly growingare number of service providers network equipment have become still derived from data andand voice services based onvendors legacy transport involved in the development and interoperability testing for the MPLS-based pseudowire technologies.
As Layer the protocol while new carriers would over like to sell the lucrative 2 specification and services implementation have matured over the past couple of years, thecases standardsover their existing Layer 3 cores. The solution in these is a based pseudowiretechnology emulation that products different vendors have3achieved an wouldfrom allow Layer 2equipment transport over a Layer excellent level of infrastructure.
In the service provider space, the deployment has gained significant momentum. This book Network Operation Complexity assists readers looking to meet those requirements by explaining the history and implementation details of the twoAToM technologies from The previous sections highlighted the advanced features that can offeravailable as the MPLSthe Cisco Unified VPN suite: However, they come with a substantial level of complexity in based cores and Layer 2 Tunneling Protocol L2TPv3 for native network design and operation, which involves more than just version enabling3 new protocols in the IP cores.
The structure of this book is focused on first introducing network. Making effective use of these features requires fine-tuning on the networkthe parameters reader tocharacteristics. Layer 2 VPN benefits and implementation requirements and according to the network comparing them to those of Layer 3 based VPNs, such as MPLS, then progressively covering each solution in greater detail.
When an operating problem occurs, AToM alsocurrently requiresavailable highly sophisticated expertise and skills to troubleshoot the issue.
For example, LDP is an out-of-band signaling protocol. For a single pseudowire, the control packets might take a different path from the data packets. Therefore, the liveliness of the control plane does not serve as a good indication for that of the data plane, in which case you need more sophisticated diagnosis methods to verify the data plane connectivity, such as MPLS ping. Establishing AToM pseudowires successfully requires the maximum transmission unit MTU settings of both attachment circuits connecting through the pseudowire to match.
Because these packets generally do not have an IP header, fragmentation is difficult. That is why packets exceeding the network MTU are dropped. March 10, do not want to deploy MPLS technologies.
Like many other networking problems, you have ISBN: Reduce costs and extend the reach of your services by unifying your L2TPv2 was originally designed for remote access solutions, and it only supports one type of network architecture Layer 2 frames: Retaining many protocol specifications of version 2, L2TPv3 enhances the control protocol and optimizes the header encapsulation for tunneling multiple types of Layer 2 Gain from the first book to address Layer 2 VPN application utilizing frames over a packet-based network.
Review strategies allow large enterprise customers to enhance their service offerings while maintaining routing control L2TPv3 consists of a control plane that uses an in-band and reliable signaling protocol to manage the control data connections L2TP endpoints, and a of data plane that is Forand a majority of Service between Providers, a significant portion their revenues responsible for pseudowire encapsulation and provides a best-effort data-forwarding service.
In are still derived from data and voice services based on legacy transport the L2TPv3 network reference models, L2TPv3 is implemented and deployed between a pair of technologies. Ideally, carriers with existing L2TPv3. This book full size image]requirements by explaining the assists readers looking[View to meet those history and implementation details of the two technologies available from the Cisco Unified VPN suite: In other words, a one-to-one mapping exists between sessions and pseudowires.
A session or pseudowire consists of two session IDs. The difference is that the baseline L2TPv3 protocol specification is responsible for constructing such a bidirectional pseudowire, whereas AToM relies on an application-level mechanism that is built 2 VPNspecification Architectures for the same function.
However, because protocols, Index. Master the world of Layer 2 VPNs to provide enhanced services and enjoy productivity gains Besides using the L2TPv3 control messages to set up pseudowires dynamically, you can use manual configuration to provision the necessary session parameters. Ideally, carriers with existing legacy Layer 2 and Layer 3 networks would like to move toward a single Even though L2TPbackbone is labeledwhile as annew IP-based technology, in fact a transport-independent carriers would like ittoissell the lucrative Layer 2 protocol.
L2TPv2,services which isover mostly deployed remote access applications, specifies their existingfor Layer 3 cores. The scenarios. Sessions readers looking to meet requirements explaining the that are destined to the same PE and router are multiplexed by session IDs into a common IP or UDP history implementation details of the two technologies available from header.
The structure of thisalong bookwith is focused on first Therefore, introducingthe thetunnel endpoints need toreader have atodeterministic to distinguish one type from the other.
However,progressively L2TP over IP covering has a different L2TP header that does not in have a field for such each currently available solution greater detail.
The discrepancy of the two L2TP header formats is a result of optimization weighted toward different deployment models. The IP transport mode is more tailored for implementing L2TP packet processing and forwarding in high-speed hardware architectures. Figure shows an overview of the two formats of an L2TPv3 packet.
Master the world of Layer 2 VPNs to provide enhanced services and enjoy productivity gains Learn about Layer 2 Virtual Private Networks VPNs Reduce costs and extend the reach of your services by unifying your network architecture Gain from the first book to address Layer 2 VPN application utilizing both ATOM and L2TP protocols Review strategies that allow large enterprise customers to enhance their service offerings while maintaining routing control For a majority of Service Providers, a significant portion of their revenues L2TP implementsare a low-overhead reliable delivery mechanism control packets at the still derived from data and voice services for based on legacy transport underlying transport layerthat is, IP or UDP.
The upper-level functions of L2TP do technologies. L2TP also uses a sliding window customers, they have some drawbacks. Ideally, carriers with existing scheme for control packet transmission to avoid overwhelming the In addition, legacy Layer 2 and Layer 3 networks would like toreceiver.
The structure of this book is focused on first introducing the merely forward PPP frames between the peering CE routers transparently. It allows transportation Cisco then HDLC frames progressively covering each currently available solution in greater detail. Bridging protocol support varies.
Cisco Pressnot need to reconstruct the Frame Relay header before forwarding the packets to the CE router. These services modes determine productivity gains granularity of how ATM packets and cells should be classified and mapped to pseudowires.
Reduce costs and extend the reach of your services by unifying your network architecture For organizations and companies that decide to stay with their existing IP-based network infrastructures for the long term and do not intend to migrate to MPLS-enabled networks, Gain from firstservices book to is address Layer VPN application utilizing choosing L2TPv3 to provide Layerthe 2 VPN obvious.
Existing Network For Installation a majority of Base Service Providers, a significant portion of their revenues are still derived from data and voice services based on legacy transport technologies.
Although Layer legacy 3 MPLSnetworks VPNs fulfill the market for some For service providers that do not have parallel and those thatneed traditionally customers, some carriers withdoes existing provide only Layer 3 services,they the have problem of drawbacks. The solution in these cases is a As telecommunication deregulation has taken place,2these service providers started technology that would allow Layer transport over a Layer have 3 eyeing lucrative Layer 2 VPN services.
The fastest and least expensive way to provide Layer 2 infrastructure. In some cases, existing edge to routers readily provide Layer 2 VPN services with history and implementation of the two technologies from proper software upgrades. This is particularlydetails attractive to service providers available that are interested the Cisco Unifiedwith VPNminimal suite: The structure of this book isto focused on and first manage introducing the network connections among geographically dispersed locations.
Not only is the Layer 2 service reader to Layer 2 VPN benefits and implementation requirements and expensive, but interprovider Layerto 2 those circuits be provisioned when thesethen locations are comparing them ofmust Layeralso 3 based VPNs, such as MPLS, not covered by a progressively single service covering provider. L2TPv3 can be an attractive cost-cutting and easy-to-manage alternative.
Instead of getting expensive Layer 2 circuits from service providers, each site can purchase the best and least expensive IP service from a local service provider without worrying about the interprovider agreement issue because IP connectivity always exists among service providers. Cisco site-to-site Press combination gives them not only Layer 2 connectivity but data integrity and privacy Pub Date: March 10, across public or shared network infrastructures.
With when transporting sensitive information ISBN: Therefore, Pages: Whenever possible, you should set the MTU of both attachment circuits that are connected through a pseudowire to the same value, and set the network MTU to accommodate the resulting L2TPencapsulated packets that carry the Layer 2 payload. L2TPv2 is a widely deployed andofhighly interoperable especially access, For a majority Service Providers, aprotocol, significant portion in of remote their revenues wholesale dial and broadband networks.
It has a large vendor support base.
Ideally, carriers withand existing of L2TPv2. The control plane procedures are almost identical in both versions. One the main legacy Layer 2 and Layer 3 networks would like to move toward a of single differences lies inbackbone the L2TP header format, which has more impact on the data plane. The solution in these cases is a 2 protocol that is carried in L2TP.
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