Metro Ethernet Network With Scaled Broadcast And Service Instance Domains
A method of operation for a provider edge device of a core network includes receiving a customer frame from an access network; the customer frame having a first Virtual Local Area Network (VLAN) tag of a first predetermined bit length. The first VLAN tag including a service instance identifier. The service instance identifier of the first VLAN tag is then mapped into a second VLAN tag of a second predetermined bit length greater than the first predetermined bit length. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72(b).
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The present application is related to co-pending application serial nos. ______ filed ______, entitled, “System And Method For DSL Subscriber Identification Over Ethernet Network”; ______ filed _______, entitled, “A Comprehensive Model For VPLS”; and ______ filed ______, entitled, “Scalable System And Method For DSL Subscriber Traffic Over An Ethernet Network”, which applications are assigned to the assignee of the present application.
FIELD OF THE INVENTIONThe present invention relates generally to digital computer network technology; more particularly, to methods and apparatus for providing metro Ethernet services.
BACKGROUND OF THE INVENTIONEthernet originated based on the idea of peers on a network sending messages in what was essentially a common wire or channel. Each peer has a globally unique key, known as the Media Access Control (MAC) address to ensure that all systems in an Ethernet have distinct addresses. Most modern Ethernet installations use Ethernet switches (also referred to as “bridges”) to implement an Ethernet “cloud” or “island” that provides connectivity to the attached devices. The switch functions as an intelligent data traffic forwarder in which frames are sent to ports where the destination device is attached. Examples of network switches for use in Ethernet network environments are found in U.S. Pat. Nos. 6,850,542, 6,813,268 and 6,850,521.
The IEEE 802.1Q specification defines a standard for Virtual Local Area Network (VLAN). Broadcast and multicast frames are constrained by VLAN boundaries such that only devices whose ports are members of the same VLAN see those frames. Since 802.1Q VLANS typically span many bridges across area common network, identification of VLANs is achieved by inserting a tag into the Ethernet frame. For example, according to the existing standard, a 12-bit tag that uniquely identifies a VLAN may be inserted into an Ethernet frame. This VLAN tag may be used to specify the broadcast domain and to identify the customer associated with a particular VLAN. The customer identifier is commonly referred to as the service instance domain since it identifies the service provided for a particular customer. In a service provider (SP) metro Ethernet network, the broadcast domain constrains the scope of traffic among network devices such that data packets are not multicast to all devices connected to the network. A system and method for efficiently distributing multicast messages within computer networks configured to have one or more VLAN domains is disclosed in U.S. Pat. No. 6,839,348.
The concept of a broadcast and a service instance domains is illustrated in
Data packet format 12 corresponds to the proposed IEEE 802.1ad specification that supports so-called “Q-in-Q” encapsulation, or tag stacking mechanism. According to this draft standard, each data packet includes an upper (i.e., outer) 12-bit tag that designates one of up to 4,094 broadcast domains (or VLANs), and a lower (i.e., inner) tag that identifies one of up to 4,094 service instances. The proposed IEEE 802.1ad standard thus alleviates some of the capacity limitations inherent in the IEEE 802.1Q standard by permitting each broadcast domain (each VLAN) to include up to 4,094 service instances. However, although the 802.1ad draft standard is capable of satisfying many multipoint applications, it remains inadequate for point-to-point applications where a single device can multiplex/de-multiplex tens of thousands or hundreds of thousands of service instances within a single broadcast domain. Furthermore, the number of broadcast domains in Metro Area Network (MAN)/WAN applications can easily exceed the 4K limit. In addition, there are certain applications that require the end-user MAC addresses and/or the end-users Frame Check Sum (FCS) to be tunneled through the MAN/WAN Ethernet network, a feature which is unsupported by the 802.1ad proposal.
Nortel Networks Corporation has proposed an approach known as “MAC-in-MAC” that attempts to solve the drawbacks inherent in the prior art. The Nortel proposal, however, is based on a flat VLAN domain (i.e., no VLAN tag stacking) and has a number of disadvantages. First, the MAC-in-MAC approach does not differentiate between broadcast domains and service instance domains; therefore, if the number of service instances is substantially larger than the required number of broadcast domains, the network nodes (i.e., switches, bridges, routers, etc.) will be burdened with supporting as many broadcast domains as there are service instances. Since more hardware/software intensive resources are needed to support a broadcast domain than a service instance, bandwidth suffers and network costs increase. Additionally, the MAC-in-MAC approach lacks inter-operability with 802.1ad bridges; lacks a feasible implementation capable of supporting millions of broadcast domains; and requires that all bridges within the network have the MAC-in-MAC capability, not just the edge bridges.
By way of further background, U.S. Pat. No. 6,789,121 discloses a method of providing a Virtual Private Network (VPN) service through a shared network infrastructure comprising interconnected PE devices having CE interfaces. Some of the CE interfaces are allocated to a VPN supporting a plurality of VLANs and are arranged for exchanging traffic data units with respective CE devices, each traffic data unit including a VLAN identifier. A virtual connection (VC) in the shared network infrastructure is directly derived from a known VPN identifier and a VLAN identifier known or discovered by a PE device. U.S. Pat. No. 6,484,209 teaches a system configured to forward multicast data based upon a first set of correlation data, wherein a first set of correlation data maps multicast group identifiers to ports that are members of the corresponding multicast groups. The switch core includes a second set of correlation data which maps multicast group identifiers to I/O cards that include member ports.
Thus, there is a need for alternative methods and apparatus that would accommodate the ever expanding number of broadcast domains and service instances of MAN/WAN Ethernet Networks while overcoming the shortcomings of past approaches.
The present invention will be understood more fully from the detailed description that follows and from the accompanying drawings, which however, should not be taken to limit the invention to the specific embodiments shown, but are for explanation and understanding only.
An extended VLAN (E-VLAN) mechanism that can differentiate between broadcast domains and service instance domains, and expands the number of broadcast domains and service instance domains in Ethernet MAN/WAN applications is described. In the following description specific details are set forth, such as device types, protocols, configurations, etc., in order to provide a thorough understanding of the present invention. However, persons having ordinary skill in the networking arts will appreciate that these specific details may not be needed to practice the present invention.
A computer network is a geographically distributed collection of interconnected subnetworks for transporting data between nodes, such as intermediate nodes and end nodes. A local area network (LAN) is an example of such a subnetwork; a plurality of LANs may be further interconnected by an intermediate network node, such as a router or switch, to extend the effective “size” of the computer network and increase the number of communicating nodes. Examples of the end nodes may include servers and personal computers. The nodes typically communicate by exchanging discrete frames or packets of data according to predefined protocols. In this context, a protocol consists of a set of rules defining how the nodes interact with each other.
Each node typically comprises a number of basic subsystems including a processor, a main memory and an input/output (I/O) subsystem. Data is transferred between the main memory (“system memory”) and processor subsystem over a memory bus, and between the processor and I/O subsystems over a system bus. Examples of the system bus may include the conventional lightning data transport (or hyper transport) bus and the conventional peripheral component [computer] interconnect (PCI) bus. The processor subsystem may comprise a single-chip processor and system controller device that incorporates a set of functions including a system memory controller, support for one or more system buses and direct memory access (DMA) engines. In general, the single-chip device is designed for general-purpose use and is not heavily optimized for networking applications.
In a typical networking application, packets are received from a framer, such as an Ethernet media access control (MAC) controller, of the I/O subsystem attached to the system bus. A DMA engine in the MAC controller is provided a list of addresses (e.g., in the form of a descriptor ring in a system memory) for buffers it may access in the system memory. As each packet is received at the MAC controller, the DMA engine obtains ownership of (“masters”) the system bus to access a next descriptor ring to obtain a next buffer address in the system memory at which it may, e.g., store (“write”) data contained in the packet. The DMA engine may need to issue many write operations over the system bus to transfer all of the packet data.
As will become apparent shortly, the E-VLAN tag mechanism can be used in many different applications. For instance, when the E-VLAN tag is utilized as a service instance identifier, the E-VLAN tag may be embedded within an IEEE 802.1ad frame, replacing the inner tag normally associated with an 802.1ad frame. In such applications, there can be 4,094 broadcast domains, with each broadcast domain supporting up to one million service instances. In applications where a given service instance requires its own broadcast domain (i.e., one-to-one correspondence) a single E-VLAN tag may be utilized as both the broadcast domain identifier and the service instance identifier. In such applications, the E-VLAN tag is the only tag in the Ethernet frame.
In still other cases, two E-VLAN tags may be utilized (i.e., one as the broadcast domain and the other one as service instance domain identifiers). In such applications, the E-VLAN tag is nested such that the outer tag represents the broadcast domain and the inner tag represents the service instance. Examples of these types of applications include situations where there are tens of thousands of broadcast domains, where each broadcast domain has up to one million service instances. Note that in applications where the E-VLAN tag is nested, a single Ethertype may be used, and the S bit will be set to indicate tag stacking.
The extended E-VLAN tag of the present invention can also be used to indicate if the Ethernet frame contains end-user's FCS, for applications were FCS retention is required, as well as to identify when the Ethernet frame contains the end-user's MAC addresses, for applications where MAC tunneling is required.
According to the embodiment of
Traffic traversing the right-hand side of the diagram of
It is appreciated that each of the u-PE and n-PE devices shown in the embodiment of
Note that in the embodiment shown in
The embodiment of
Turning now to
The E-VLAN tag remains unchanged through core network 20 and access network 22. However, it is appreciated that the VLAN tag designating the broadcast domain in access network 21 differs from the broadcast domain VLAN tag in core network 20, which also differs from the VLAN designating the broadcast domain in access network 22. That is, the only thing that n-PE devices 32 & 33 change in the data packets is the upper VLAN tag that defines the scope of the broadcast domain.
The embodiment of
It should also be understood that elements of the present invention may also be provided as a computer program product which may include a machine-readable medium having stored thereon instructions which may be used to program a computer (e.g., a processor or other electronic device) to perform a sequence of operations. Alternatively, the operations may be performed by a combination of hardware and software. The machine-readable medium may include, but is not limited to, floppy diskettes, optical disks, CD-ROMs, and magneto-optical disks, ROMs, RAMs, EPROMs, EEPROMs, magnet or optical cards, propagation media or other type of media/machine-readable medium suitable for storing electronic instructions. For example, elements of the present invention may be downloaded as a computer program product, wherein the program may be transferred from a remote computer (e.g., a server) to a requesting computer (e.g., a customer or client) by way of data signals embodied in a carrier wave or other propagation medium via a communication link (e.g., a modem or network connection).
Additionally, although the present invention has been described in conjunction with specific embodiments, numerous modifications and alterations are well within the scope of the present invention. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense.
Claims
1. A method of operation for a network-facing provider edge device (n-PE) of a core network, the method comprising:
- receiving a customer frame from an access network of a service provide (SP) associated with a core network, the customer frame having a first Virtual Local Area Network (VLAN) tag of a first predetermined bit length, the first VLAN tag including broadcast and service instance identifiers for connections across the access network;
- mapping the service instance identifier of the first VLAN tag into a second VLAN tag of a second predetermined bit length greater than the first predetermined bit length; and
- encapsulating the customer frame with a provide address header.
2. (canceled)
3. The method of claim 1 further comprising:
- stacking a third VLAN tag on the second VLAN tag, the third VLAN tag being different from the second VLAN tag.
4. The method of claim 1 wherein the core network comprises an Ethernet core network.
5. The method of claim 1 wherein core network comprises a Multi-protocol label switching (MPLS)/Internet Protocol (IP) network.
6. The method of claim 1 wherein the first predetermined bit length is 12-bits and the second predetermined bit length is 20-bits.
7-11. (canceled)
12. A method of operation for a network-facing provider edge device (n-PE) of a core network, the method comprising:
- receiving a customer frame from an access network of an SP associated with a core network, the customer frame having a customer Media Access Control (MAC) header, a customer Virtual Local Area Network (VLAN) tag and a first Virtual Local Area Network (VLAN) tag of a first predetermined bit length, the first VLAN tag including broadcast and service a serviceinstance identifier identifiers for connections across the access network; and
- mapping the service instance identifier of the first VLAN tag into a second VLAN tag of a second predetermined bit length greater than the first predetermined bit length, the second VLAN tag specifying a broadcast domain and a service instance domain of the core network; and
- encapsulating the customer frame within a provider address header.
13.-14. (canceled)
15. The method of claim 12 wherein the core network comprises an Ethernet core network.
16. The method of claim 12 wherein the access network comprises an Ethernet access network.
17. The method of claim 12 wherein the first predetermined bit length is 12-bits and the second predetermined bit length is 20-bits.
18. A method of operation for a user-facing provider edge device (u-PE) of an access network, the method comprising:
- receiving a customer frame from a customer edge (CE) device;
- adding a first Virtual Local Area Network (VLAN) tag to the customer frame, the first VLAN tag designating a broadcast domain in an access network; and
- adding a second VLAN tag having a bit length of 20-bits or more to the customer frame, the second VLAN tag designating a service instance identifiers identifier in the access network; and
- encapsulating the customer frame with a provider address header.
19. (canceled)
20. The method of claim 18 wherein the access network comprises an Ethernet access network.
21. A network-facing provider edge (n-PE) device comprising:
- a port to receive a customer frame from an access network associated with a service provider (SP), the customer frame having a first Virtual Local Area Network (VLAN) tag of a first predetermined bit length, the first VLAN tag including a service instance identifier; and
- a processing unit configured to: map the service instance identifier of the first VLAN tag into a second VLAN tag of a second predetermined bit length greater than the first predetermined bit length; and
- encapsulate the customer frame with a provider address header, and also to stack a third VLAN tag on the second VLAN tag, the third VLAN tag specifying a broadcast domain for connections across a core network of the SP.
22. (canceled)
23. The n-PE device of claim 21 wherein the processing unit is further configured to stack a third VLAN tag on the second VLAN tag, the third VLAN tag being different from the second VLAN tag.
24. The n-PE device of claim 21 wherein the first predetermined bit length is 12-bits and the second predetermined bit length is 20-bits.
25-26. (canceled)
27. A network-facing provider edge device (n-PE) device comprising:
- a port configured to receive a customer frame from an access network, the customer frame having a customer Media Access Control (MAC) header, a customer Virtual Local Area Network (VLAN) tag and a first VLAN tag of a first predetermined bit length, the first VLAN tag including broadcast and service instance identifiers for connections across the access network; and
- a processing unit configured to: that maps map the broadcast and service instance identifier identifiers of the first VLAN tag into a second VLAN tag of a second predetermined bit length greater than the first predetermined bit length, the second VLAN tag designating a broadcast domain and a service instance domain through a service provider (SP) core network, and encapsulate the customer frame within a SP address header.
28-29. (canceled)
30. The n-PE device of claim 27 wherein the first predetermined bit length is 12-bits and the second predetermined bit length is 20-bits.
31. A user-facing provider edge device (u-PE) device comprising:
- a port configured to receive a customer frame from a customer edge (CE) device, the customer frame including a customer VLAN and a customer Media Access Control (MAC) header; and
- a processing unit configured to: add a Virtual Local Area Network (VLAN) tag having a bit length of 20-bits or more to the customer frame, the VLAN tag including broadcast domain and a service instance identifiers designating a broadcast domain and a service instance domain, respectively, for connections across the Ethernet access network and through a core network of a service provide (SP); and encapsulate the customer frame within a SP MAC header.
32. (canceled)
33. A provider edge device comprising:
- a plurality of ports; and
- means for adding a first and second Extended Virtual Local Area Network (E-VLAN) tags to a first frame received at a first port for transmission across a service provider (SP) core network, the first frame including a customer Media Access Control (MAC) header and a customer VLAN tag, the first E-VLAN tag designating a broadcast domain through an access network associated with the service provider (SP) core network, the first frame including a customer Media Access Control (MAC) header and a customer VLAN tag, the first E-VLAN tag designating a broadcast domain through an access network associated with the service provider (SP) core network, and the second E-VLAN tag identifying a service instance through the access network and the service provide (SP) core network, the means also for encapsulating the first frame with a provider address header, the means also for dropping the first and second E-VLAN tags.
34.-36. (canceled)
Type: Application
Filed: Apr 17, 2012
Publication Date: Aug 9, 2012
Applicant: Cisco Technology, Inc. (San Jose, CA)
Inventors: Ali Sajassi (San Ramon, CA), Norman W. Finn (Livermore, CA)
Application Number: 13/448,588
International Classification: H04L 12/56 (20060101);