CN107040442B - Communication method, communication system and cache router of metropolitan area transport network - Google Patents

Abstract

The application relates to a communication method, a communication system and a cache router of a metropolitan area transport network. Techniques are described that enable local caching of content data within a metro transport network for delivery to customers of an ISP connected to the metro transport network. Routers within the metro transport network (including a provider edge router towards the ISP and one or more cache routers) establish an EVPN within the metro transport network. The access router outputs within the EVPN to the cache router an EVPN route advertisement representing the network address reachability information of the user device notified by the ISP. In response to a user content request redirected from an ISP and based on EVPN routing advertisements from the access router, a cache router of the metro transport network forwards content from a local content cache to the access router via EVPN for efficient delivery to one or more users.

Description

Communication method, communication system and cache router of metropolitan area transport network

This application is continued in part with U.S. application serial No. 14/984,903 filed on 30/12/2015, which is incorporated herein by reference in its entirety.

Technical Field

The present disclosure relates to computer networks and, more particularly, to delivering content to users over metropolitan access networks.

Background

In this manner, metropolitan area transport networks are typically used as access networks that provide high-speed layer 2 (L2) transport, e.g., Ethernet connectivity, between a user and its Internet service provider network.

Metropolitan area transport networks typically provide a layer 2 (L2) exchange for the transmission of packet-based data between users and their respective ISPs, such that IP (layer 3-L3) communication sessions may be established for users at the ISPs for communicating with resources beyond the ISPs, e.g., content data networks or the internet.

Disclosure of Invention

In general, techniques are described that enable local caching of content data within a metro transport network for direct delivery to customers of an Internet Service Provider (ISP) connected to the metro transport network. As used herein, these techniques enable ISPs and other content providers to distribute content to users using local content caching within a metro transport network, thereby enhancing the user experience. However, the ISP network may remain in possession of the IP services provided to the user, including authentication, billing, and other services. In other words, even though IP services of a given customer may be provided and anchored by an ISP service provider located upstream of a metro transport network operating as a high speed access network for the given customer, the techniques described herein enable ISPs and other content providers to pre-load content downstream within the metro transport network for efficient service of the customer's content requests. For example, the techniques may be well suited for caching using reverse proxy techniques, where content is pre-located in a particular location within a network to enhance the user experience.

As used herein, an edge switch/router of a metro transport network implements the Ethernet Virtual Private Network (EVPN) protocol, including one or more cache provider edge (C-PE) routers, as members of the EVPN. An ISP associated with the metro transport network and the metro carrier cooperate such that the access edge router of the EVPN informs the network address reachability information (e.g., IP prefix of the ISP or IP/MAC combination) into the EVPN on behalf of the ISP, wherein the advertisement specifies that the network address information owned by the ISP and used to provide IP services to the user is actually reachable through the access edge router.

Moreover, the C-PE router is collocated with one or more local caches located within the metro transport network, and the C-PE router and/or any other router of the metro transport network declares that the local caches are up-stream to an internet service provider, e.g., via external BGP (E-BGP) routing sessions. In this way, the C-PE shares locally cached IP prefix reachability information within the metro transport network with the ISP network and upstream border routers of the Content Delivery Network (CDN). Likewise, a DNS server or content server within the ISP may redirect user content requests back downstream into a local cache within the metro transport network so that cached content may be delivered directly from the metro transport network to the user. In this manner, the techniques may enable a content server at an ISP or content data network to distribute cached content proximate to the user, thereby improving user experience and satisfaction.

A metro network including the access router and the cache router establishes an EVPN within the metro network and the access router outputs an EVPN routing advertisement within the EVPN to the cache router that advertises an IP network address prefix on behalf of the Internet service provider network.

In another example, a method includes establishing an Ethernet Virtual Private Network (EVPN) within a metro network located between at least one internet service provider network and a set of user devices, the metro network providing layer 2 (L2) data packet exchange for transporting network data packets between the internet service provider network and the user devices, the internet service provider network authenticating the user devices and assigning corresponding IP network addresses to the user devices from a L3 network address prefix assigned to the internet service provider network, receiving an EVPN route advertisement from an access router connected to the user devices by one or more access links and coupled to a local content cache of the metro network within the metro network by at least one cache router coupled to the local content cache of the metro network, the advertisement notifying the IP address (/32 host address) or the IP prefix on behalf of the internet service provider network, wherein the EVPN route advertisement specifies that the service provider network is served by the metro network and further includes an advertisement request from the local content cache router for redirection from the internet service provider network by the access router to the internet service provider network via the internet service network address cache router, and wherein the EVPN route advertisement request is forwarded to the customer device via the access network address through the internet service provider network address and the internet network address.

In another example, a cache router is located within a metro transport network between at least one internet service provider network and a set of user devices. The cache router includes a control unit having at least one processor coupled to a memory. The control unit executes software configured to establish an Ethernet Virtual Private Network (EVPN) with one or more access routers within the metro transport network. The control unit is configured to receive an EVPN routing advertisement specifying an IP address/prefix assigned to an internet service provider network. The EVPN route advertisement specifies an IP address or prefix of the internet service provider network and indicates that the IP address assigned to the user from the pool/prefix of IP addresses of the internet service provider network is reachable through the access router of the EVPN. The cache router of the metropolitan area transmission network outputs a routing protocol routing advertisement, and the advertisement informs the router of the internet service provider network of the network address reachability information of the local content cache of the metropolitan area transmission network. In response to a content request redirected from the internet service provider network and based on EVPN routing advertisements, a cache router of the metro transmission network forwards content from a local content cache to the access router for transmission to one or more customers via EVPN.

In another example, a non-transitory computer readable storage medium includes executable instructions configured to perform the methods described herein.

The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.

Drawings

FIG. 1 is a block diagram illustrating an example prior art network system;

FIG. 2 is a block diagram illustrating an example network system in accordance with the techniques described herein;

FIG. 3 is a block diagram illustrating further details of an example router, in accordance with techniques of this disclosure;

fig. 4 is a flow diagram illustrating example operations of a plurality of network devices in accordance with the techniques of this disclosure.

Detailed Description

Fig. 1 is a block diagram illustrating an example network system 2 in accordance with the techniques described herein. As shown in the example of fig. 1, network system 2 includes a metro access and aggregation network 4 coupled to an internet service provider network 7. Typically, the internet service provider network 7 is typically owned by an Internet Service Provider (ISP) and serves as a private network that provides packet-based network services to the user devices 18A, 18B (herein, "user devices 18"). The user device 18A may be, for example, a personal computer, laptop computer, or other type of computing device associated with a user, such as a smart television, wireless enabled notebook, gaming device, smart phone, Personal Digital Assistant (PDA), etc., that is connected to the network through a customer premises switch or router (CPE). Each user device 18 may run various software applications such as word processing and other office support software, web browsing software, software that supports streaming media content for services (e.g., Netflix and YouTube), software that supports voice calls, video games, video conferencing, and email, among others. That is, the internet service provider network 7 provides authentication and establishment of network access for the user devices 18 so that the user devices can begin exchanging data packets over the internet backbone 12 to retrieve content from the content servers 15 of the ISP 7 or through one or more Content Data Networks (CDNs) 8.

Generally, the content hosted and delivered by content server 15 or CDN8 to users 18 may include, for example, streaming media files, data files, software distributions, documents, and so forth. Content may be delivered to user 18 by various services and protocols, such as hypertext transfer protocol (HTTP), HTTP-based adaptive streaming, real-time streaming protocol (RTSP) streaming, other media streaming, peer-to-peer (P2P) protocol, File Transfer Protocol (FTP), and so forth. CDN8 is typically a private network of interconnected devices that cooperate to distribute content to customers using one or more services. The CDN8 may comprise one or more data centers having data servers, web servers, application servers, databases, computer clusters, mainframe computers, and any other type of server, computing component, and/or database that may be used by a content service provider to facilitate the delivery of content to user devices 18 through the internet backbone 12 and internet service provider network 7.

In the example of fig. 1, a metro transport network 24 provides layer 2 (L2) ethernet switched transport services with network traffic associated with user devices 18. the metro transport network 24 typically includes internal transport nodes ("N") 19, e.g., ethernet switches and underlying transport systems, for transport, multiplexing, and switched communications over high speed links between access provider edge routers (a-PEs) 36 and network provider edge routers (N-PEs) 30. although only a single internet service provider network 7 is shown for simplicity, the metro transport network 24 may provide access, aggregation, and transport of data packets to user devices 18 of multiple different internet service providers.

In the example of fig. 1, a-PE36 operates at the boundary of metro transport network 24 and provides connectivity to access network 27, respectively, AN 27 generally provides access to metro transport network 24 to customer devices 18 and CPEs 18, for example, a-PE36 generally includes functionality to aggregate the output of one or more endpoints associated with customer devices 18 into the high speed uplink of metro transport network 24, for example, customer devices 18 may be connected to local Customer Premises Equipment (CPE), such as DS L or a cable modem, and a-PE36 may include digital subscriber line access multiplexing equipment (DS L AM) or other switching devices.

Typically, the user device 18/CPE 18 is associated with a customer of an internet service provider that owns and operates the internet service provider network 7. Likewise, the internet service provider network 7 processes authentication and session establishment to provide network access to the user device 18. A Broadband Network Gateway (BNG)23 provides routing and switching functions for connecting to the metro transport network 24 through the N-PE 30 and provides endpoints of IP sessions established for the user devices 18 and management of the IP sessions. In another example, BNG 23 can be a Broadband Remote Access Server (BRAS) or other routing device that provides an anchor point for user sessions.

The Internet service provider network 7 assigns IP addresses (public/Internet routable or private) from the service provider's IP domain to users upon authenticating the provisioned user devices 18/CPE 18 and provides IP connectivity (L3) services to communication sessions associated with the users, for example, the AAA server 111 of the service provider network 7 is typically an authentication, authorization and accounting (AAA) server to authenticate credentials of users requesting network connections. the AAA server 11 may be, for example, a remote authentication Dial-in user service (RADIUS) server As another example, the AAA server 11 may be a DIAMETER server, the AAA server 11 assigns layer 3 (L3) network addresses (e.g., IPv4 or Ipv6 network addresses) upon authenticating network access requests by the user devices 18 for receiving data services through the Internet service provider network 7. the policy control server 14 represents a network device that provides policy control and accounting rules function (PCRF) for the user devices 18.

In this manner, layer 2 (L) network transport functions and layer 3 (L) network functions are generally divided between the metro transport network 24 and the internet Service provider network 7, respectively as AN example, the metro transport network 24 implements Virtual Private local area network traffic (VP L S) or Ethernet Virtual Private Network (EVPN) services that enable the metro transport network 24 to serve as a L network for transporting L traffic of the user device 18 to the BNG 23 implements L functions, i.e., address assignment and routing of the user device 18 within the user' S corresponding internet Service provider 633, i.e., in this example, ISP network 7, for example, by implementing VP L S or EVPN E-L AN services, the metro transport network 24 communicates over transport network L, e.g., ethernet packets are communicated over transport network 24, as this document, ethernet packets are filed on a month 1 entitled "Virtual Private L AN (VP L S) for internet services-this document," which may be found in relation to internet services information as mentioned in the OSI transport network data layer 7432, which is also referred to by the OSI Model publication number of international publication No. the internet protocol for the internet Service publication.

After authentication and establishment of network access through the internet service provider network 7, any of the user devices 18 may begin exchanging data packets with the CDN 8. in this process, the IP address assigned to the user device 18 by the internet service provider network 7 may be translated into a public address associated with a routing prefix of the internet service provider network 7 for purposes of packet-based communication over the internet backbone 12. furthermore, the gateway 21 provides layer 3 (L3) routing functionality for reaching the user device 18 through the internet service provider network 7. that is, the gateway 21 informs L3 reachability information (e.g., routing) for reaching the public address prefix associated with the internet service provider network 7. upon receipt of the layer 3 (L) routing information, the Autonomous System Border Router (ASBR)30 uses the network layer reachability information to reach the address prefix advertised by the internet service provider network 7 to update its corresponding routing table. likewise, routing information is used to reach the user device 18 without knowledge of the user device's 2, billing content is delivered by the internet service provider network 7 or other devices 15 for purposes of internet service provider network access to detect traffic, although the internet service packet access may not be shown to flow through the internet service provider network 7, DPI, the internet service provider network 7, the internet service provider network 14, the internet service provider network provides billing information, the internet service provider network access network for example, the internet service network access to detect the content, and other network access to provide billing information, and other network access to balance the internet service devices, the internet service network services, the internet service.

Fig. 2 is a block diagram illustrating an example network system in accordance with the techniques described herein. In particular, techniques are described that enable content data to be cached locally within the metro transport network 24 for direct delivery to the user device 18. This allows the content server of ISP 7 or CDN8 to distribute the cached content downstream to the metro transport network 24 closest to the user device 18, thereby improving user experience and satisfaction.

As shown in fig. 2, rather than implementing only layer 2 (L2) emulated services for transporting traffic, e.g., VP L S, the metro transport network 24 implements a virtual private network (EVPN) based layer 2 network to provide connectivity between the user device 18 and the internet service provider network 7, even though the internet service provider network 7 is responsible for authenticating the user device 18 and assigning a L3 network address to the user.

In one example, the metro transport network 24 implements an Ethernet Virtual Private Network (EVPN) 26. typically, edge routers (e.g., a-PE36 and N-PE 30) of the metro transport network 24 and the recently introduced cache-providing edge (C-PE) routers 80 of the metro transport network 24 operated by the metro transport bearer are configured to execute the EVPN protocol within their respective control planes (also referred to as routing engines) to communicate with each other and exchange configuration information needed to establish and maintain the EVPN 26. in EVPN, by exchanging EVPN messages according to the EVPN protocol, as opposed to conventional bridging occurring within VP L S, where L2 address learning occurs within the data plane (i.e., GRE forwarding elements) while forwarding L2 traffic, control planes of the edge L2 address learning (e.g., MAC learning) occurring within the control planes between edge routers, e.g., a-PE36, N-PE 30 and C-PE80 are configured to execute routing protocols, e.g., border enhancement protocols (e.g., edge routers) to exchange messages between each other edge routers to establish a connection with the Internet IP tunneling IP tunnel IP protocol, BGP-IP tunneling protocol, BGP termination protocol, BGP 7, IP tunneling protocol, BGP termination protocol, IP tunneling protocol, BGP termination, etc. IP 3632, etc. IP tunneling protocol, and IP tunneling protocol, so that all of the Internet tunnel discovery messages may be set up the Internet tunnel discovery messages may be used in connection to communicate with each other IP tunneling protocol.

As shown in fig. 2, the metro transport network 24 is configured to include at least one cache provider edge (C-PE) router 80 collocated with a local cache 82 storing cached content of the content server 15 or CDN8, thereby allowing the cached content to be directly transmitted from the metro transport network 24 to downstream customers within the access network of ISP 7 responsible for authentication and layer 3 (L3) services of the customers 18 as described above, the C-PE router 80 is typically owned and operated by a metro carrier and participates in EVPN 26. furthermore, the C-PE router 80 provides layer 3 (L) peering relationships, e.g., via external BGP (E-BGP) routing sessions 42 or via static routing, L3 reachability information for the metro transport network 24 shared with the ISP 7, e.g., bng., BNG 23. in particular, as described above, C-PE80 participates in EVPN 26. for example, the control plane of the C-PE80 is configured to execute and cache protocols to facilitate the transmission of the cached content from the cache provider edge 80 to the evpe 80 for direct transmission from the access point of the C-PE80 to the evpe 26 via the access point 3618.

Also, while the internet service provider network 7 still performs authentication of the user device 18 and assignment of L3 network addresses to the user, the internet service provider and metro carrier operator arrange for having network address information (e.g., respective address prefixes owned by the ISP or IP address/MAC address combination for use by the user device) advertised by the a-PE36 of the metro carrier, in lieu of or in addition to typical routing protocol advertisements from the gateway 21 of the internet service provider network 7 to the internet backbone 12. in one example, the a-PE36 is programmed by the metro carrier with address data specifying the IP prefix of any internet service provider network 7 where the ISP agrees to participate in the fast path offload techniques described herein. for example, the administrator of the metro carrier may enter lists, files or other data structures specifying the IP address advertised by the a-PE or MAC/IP address.in another example, the ISP's g 23 may be configured to leak or otherwise assign to the ISP and be communicated by the layer 3 address owned by the ISP to the a-PE (prefix) to the internet device 18, and may even provide the routing protocol messages for use by the bnpe 18, the internet service provider's routing protocol.

In response, the routing protocol executing within the control plane of A-PE36 updates the corresponding routing table to the associated ISP address Prefix, through the local interface port, to reach the user device 18. furthermore, the routing protocol of A-PE36 is configured to output an EVPN message 41 to inform the EVPN26 layer 3 Prefix or IP address/MAC address combination on behalf of the Internet service provider network 7, wherein the EVPN message 41 announces that the IP address assigned from the IP Prefix used by the Internet service provider network 7 can actually be reached by the A-Pe to provide IP services to the user device 18. As an example, the A-PE36 can reconstruct the EVPN message 41 as an IP Prefix advertisement route (i.e., route type 5) for BGP EVPN, by "IP Prefix advertisement in EVPN," draft-IETF-less-p-expression-Prefix-advertisement-01, Internet Engineering Task-service (RFC), by "IP-express-IP-Prefix-advertisement-address-01, Internet service-IP address binding information, Internet service authorization-IP-proxy-advertisement-01, Internet service-IP-proxy-advertisement-IP-.

Moreover, the C-PE router 80 communicates the reachability of the cache 82 to the ISP network 7 through a routing protocol peering session 42, which may be a BGP peering session between the control plane of the C-PE router 80 and the BNG 23. In this way, the ISP network 7 knows the direct access path of the local cache within the metro transport network 24 and, in particular, is associated with the C-PE80 as a forwarding next hop for reaching the cache 82. In many deployments, the content servers 15 and/or CDNs 8 of the ISP network 7 typically have an infrastructure for pre-distributing the content. Likewise, content server 15 or CDN8 may use reachability information learned from C-PE80 to preload cache 82 with cached content, thereby providing a locally efficient distribution mechanism for delivering content to users 18. Although C-PE80 is described in notifying the metro transport network of the reachability of the cached content for purposes of example, the content reachability may be notified by any other router. In this case, the request for content arrives at the cache through other routers.

In an example operation, the user device 18 outputs a content request 40 to request the content of the content server 15 or CDN8, typically in response to a unique identifier (e.g., a uniform resource locator (UR L)), such as www.contentservice.com., and the Domain Name Service (DNS) server 27 or alternatively the content server 15 operates to resolve the content request 82 to the cache 82 of the metro transport network based on the reachability information notified by the C-PE 80. in this manner, the ISP network 7 re-imports the content request 40 to the cache 82 through the C-PE80 as the content request 40'.

Fig. 3 is a flow diagram illustrating an example operation of a network system in accordance with the techniques described herein. First, an address prefix owned by the ISP is communicated to the metro carrier for configuration of the access provider edge router, e.g., a-PE36 (100, 102). As described above, a-PE36 may be programmed by a metro carrier with network address information for the internet service provider network, e.g., data specifying the IP address prefix of any internet service provider network 7, where the ISP agrees to participate in the fast path offload techniques described herein. As another example, the BNG 23 of the agreed upon ISP may output a message 39 to selectively transmit to the a-PE36 one or more public IP address prefixes assigned to the corresponding internet service provider network 7 and for the user device 18. As another example, BNG 23 may output one or more MAC/IP address combinations to A-PE36 on behalf of Internet service provider network 7.

Next, a-PE36 updates its respective routing table to the associated ISP address prefix, to reach user device 18 through the local interface port, and outputs EVPN message 41 to inform EVPN26 of the layer 3 prefix on behalf of internet service provider network 7, where EVPN message 41 specifies the route through a-PE that actually reaches the prefix used by internet service provider network 7 to provide IP services to user device 18 (104). Alternatively, A-PE36 may construct EVPN message 41 as a MAC + IP address advertisement route (i.e., route type 2) for a BGP EVPN to carry one or more MAC/IP address combinations on behalf of Internet service provider network 7.

As a member of EVPN26, C-PE router 80 receives the EVPN route advertisement, announces L3 that the address prefix is associated with user device 18 and is reachable through A-PE36 via EVPN26, e.g., by an EVPN type 5 route advertisement or an EVPN type 2MAC + IP route advertisement (106) advertising the IP prefix (rather than the L2 MAC address of the user). in return, C-PE router 80 updates the BGP routing table on C-PE router 80. in addition, C-PE router 80 communicates L3 reachability information for local cache 82 to ISP network 7(107) by constructing and outputting BGP messages in this example, via routing protocol peering session 42.

Upon receiving the BGP message over peering session 42, the L3 router with the ISP (e.g., BNG 23) updates its BGP routing table to associate with C-PE80 as the next hop for reaching local cache 82 within metro transport network 24 for distributing content directly from metro transport network 24 downstream (closer to customer 18) of internet service provider network 7 to customer device 18(108) based on the reachability information, content server 15 and other infrastructure of ISP network 7 deliver content to cache 82 through C-PE80 for preloading content (108) within local cache 82 of transport metro network 24 as another example, CDN8 may likewise know that local cache 82 of metro transport network 24 is reachable through C-PE80 and pre-load content into cache.

In receiving a network access request from a specified user device 18, AAA server 11 of internet service provider network 7 authenticates the user and assigns an IP address to the user from an IP network address prefix assigned to and owned by the ISP (110). accordingly, network communications can flow user sessions from the user through the switching mechanism provided by metro transport network 24 and the L3 services and routing functions provided by internet service provider network 7, into internet backbone 12 and cdn 8. likewise, either content server 15 or DNS 27 of ISP network 7 can receive content requests 40(112) from the specified user, in receiving a content request of user device 18, content server 15 or DNS 27 processes the content request and, based on the reachability information notified by C-PE80, resolves the content request 40(112) to the cache 82 of the metro transport network, hi this example, content server 15 or DNS 27 can be considered to act as a reverse proxy to reintroduce the downstream content request into the local cache 82 of the metro transport network closer to user 18. the local cache 82 is located closer to the ISP network 18 in this context and the traditional techniques of caching the content can be operated between the metro transport network 18 and the ISP 352.

Upon receiving the redirected content request 40' from the ISP network 7, the C-PE80 routes the request to the local cache 82 (113). In response, cache 82 processes the content request, if any, to retrieve the identified content and outputs cached content 43 toward user 18 via the C-PE as the next hop to the user (114). For example, local cache 82 may output an HTTP message, an RTP message, or other communication for communicating the requested content to requesting user 18. In turn, the C-PE uses the reachability information for user 18 as understood by EVPN message 41 to encapsulate buffered content 43 and inject the buffered content into EVPN26 as EVPN data packet 43' for transmission to one or more a-PEs 36(116) based on the address prefix advertised by a-PE36 within EVPN. a-PE36 receives content from EVPN26, decapsulates the contents of the transport layer EVPN packets, and forwards IP packets encapsulating the content to user device 18 (118).

Fig. 4 is a block diagram illustrating an exemplary router 180 capable of performing the disclosed techniques. In general, router 180 may operate substantially similar to A-PE36, N-PE 30, or C-PE80 described with reference to FIGS. 2-3.

In this example, router 180 includes interface cards 188A-88N ("IFC 188") that receive data packets over input links 190A-190N ("input links 190") and transmit data packets over output links 192A-192N ("output links 192"). The IFCs 188 are typically coupled to the links 190, 192 through a plurality of interface cards. The router 180 also includes a control unit 182 that determines the routing of received packets and forwards the packets accordingly via the IFCs 188.

Control unit 182 may include a routing engine 184 and a packet forwarding engine 186. Routing engine 184 operates as the control plane of router 180 and includes an operating system that provides a multitasking operating environment for executing multiple simultaneous processes. For example, routing engine 184 executes software instructions to implement one or more control plane network protocols 197. For example, protocols 197 may include one or more routing protocols, such as Border Gateway Protocol (BGP)193, for exchanging routing information with other routing devices and for updating routing information 194. Routing information 194 may describe the topology of the computer network in which router 180 is located and may also include routes through the network. The routing information 194 describes the various routes within the computer network and the appropriate next hop for each route, i.e., the adjacent routing devices along each route. Routing engine 184 analyzes stored routing information 194 and generates forwarding information 196 for forwarding engine 186. For example, forwarding information 196 may associate a user's network destination with a particular next hop and corresponding IFCs 188 and physical output ports of output links 192. Also, forwarding information 196 may specify operations, such as label encapsulation using EVPN assignments or decapsulation of data packets, to apply when forwarding the data packets to the next hop. Forwarding information 196 may be a radix tree programmed as a specialized forwarding chip, a series of tables, a complex database, a link list, a radix tree database, a flat file, or various other data structures.

In the example of fig. 4, routing engine 184 of the control plane, also referred to as router 180, executes EVPN protocol 187, which operates to communicate with other routers to establish and maintain EVPN, e.g., EVPN26, for transporting communications over metro transport network 24 so that ethernet logically extends across the intermediate network, EVPN protocol 187 communicates with EVPN protocols executing on remote routers to establish tunnels (e.g., L SP or GRE or other tunneling mechanisms, e.g., VX L AN) that use appropriate tunneling mechanisms on the packets to transport packets over the EVPN enabled networks, EVPN protocol 187 maintains MAC address table 181 within the control plane of router 180, wherein the MAC table associates L customer MAC addresses with specific tunnels for reaching associated MAC addresses, upon implementation of EVPN, by exchanging information containing customer MAC + IP addresses with remote PE devices L may be executed within the control plane L + IP address forwarding information may be configured in connection with the ethernet forwarding engine via ethernet forwarding engine 186, ethernet forwarding information may be described by ethernet forwarding table 186, which ethernet forwarding information is configured in connection with the ethernet forwarding information via ethernet tunnel 186, BGP foundation, BGP session discovery messages, ethernet session discovery messages, etc. 7432.

Further, as described herein, the BGP protocol 193 may receive IP prefix advertised routes (i.e., route type 5) for BGP EVPN26 upon receiving L3 route advertisements for EVPN, the BGP protocol 193 may output updated routing information 194 and inform routes through any BGP peering relationships, e.g., BGP sessions 42, and the BGP protocol 193 forwards L3 information to the EVPN protocol 187, which updates forwarding information 196 associated with EVPN26 to specify the appropriate next hop and encapsulation information needed to traverse packets destined for L3 prefix through EVPN.

The architecture of router 180 shown in fig. 4 is shown for exemplary purposes only. The present invention is not limited to this architecture. In other examples, router 180 may be configured in various ways. In one example, certain functions of the control unit 182 may be distributed within the IFC 188. In another example, the control unit 182 may include a plurality of packet forwarding engines operating as slave routers.

The control unit 182 may be implemented solely in software or hardware, or may be implemented as a combination of software, hardware or firmware. For example, the control unit 182 may include one or more processors that execute software instructions. In this case, the various software modules of the control unit 182 may include executable instructions stored on a computer readable medium (e.g., a computer memory or hard disk).

The techniques described herein may be implemented within hardware, software, firmware, or any combination thereof. Various features that are described as modules, units or elements may be implemented together in an integrated logic device or separately as discrete but interoperative logic devices or other hardware devices. In some cases, various features of an electronic circuit may be implemented as one or more integrated circuit devices, such as an integrated circuit chip or chipset.

If implemented within hardware, the present disclosure may relate to an apparatus, e.g., a processor or an integrated circuit device, e.g., an integrated circuit chip or chipset. Alternatively or in addition, if implemented in software or firmware, the techniques may be implemented at least in part by a computer-readable data storage medium comprising instructions that, when executed, cause a processor to perform one or more of the methods described above. For example, a computer-readable data storage medium may store such instructions for execution by a processor.

The computer readable medium may form part of a computer program product, which may include packaging materials. The computer-readable medium may include a computer-readable storage medium, such as Random Access Memory (RAM), read-only memory (ROM), non-volatile random access memory (NVRAM), electrically erasable programmable read-only memory (EEPROM), flash memory, magnetic or optical data storage media, and the like. In some examples, an article of manufacture may include one or more computer-readable storage media.

In some examples, a computer-readable storage medium may include a non-transitory medium. The term "non-transitory" may mean that the storage medium is not embodied in a carrier wave or propagated signal. In some instances, a persistent storage medium may store data that may change over time (e.g., within a RAM or cache).

The code or instructions may be software and/or firmware executed by processing circuitry including one or more processors, such as one or more Digital Signal Processors (DSPs), general purpose microprocessors, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), or other equivalent integrated or discrete logic circuitry. Thus, the term "processor" as used herein may represent any of the above structures or any other structure suitable for implementing the techniques described herein. Further, in some aspects, the functionality described in this disclosure may be provided within software modules or hardware modules.

Various embodiments are described. These and other embodiments are within the scope of the following examples.

Claims (12)

1. A method of communication, comprising:

establishing an Ethernet virtual private network within a metro transport network located between at least one Internet service provider network and a set of user devices, wherein said metro transport network provides layer 2 packet switching for transporting network packets between said Internet service provider network and said user devices, wherein said Internet service provider network authenticates said user devices and assigns corresponding Internet protocol network addresses to said user devices from Internet protocol network address prefixes assigned to said Internet service provider network, and wherein said customer devices are authenticated by at least one access router connected to said user devices by one or more access links, at least one cache router coupled to a local content cache of said transport metro network, and at least one network provider edge configured and operable to carry traffic between said at least one Internet service provider network and said metro transport network The router establishes the Ethernet virtual private network in the metropolitan area transmission network;

receiving, by a cache router of the Ethernet virtual private network, an Ethernet virtual private network route advertisement from the access router, the Ethernet virtual private network route advertisement informing the user device of network address reachability information on behalf of the Internet service provider network, wherein the Ethernet virtual private network route advertisement indicates that the user device is reachable through the access router;

outputting a routing protocol routing advertisement, wherein the routing protocol routing advertisement informs a router of the internet service provider network of network address reachability information of a local content cache of the metropolitan area transmission network; and is

In response to a content request redirected from the internet service provider network and based on an ethernet virtual private network router advertisement from the access router, forwarding, by a cache router of the metro transport network, content from the local content cache to the access router over the ethernet virtual private network for delivery to one or more customers.

2. The method of claim 1, wherein forwarding content from the local content cache to the one or more users comprises:

receiving, by a cache router of the metro transport network, data packets sent to one or more of the user devices from the local content cache;

encapsulating the data packets using the cache router and traversing the data packets through the Ethernet virtual private network enabled Metro transport network, entering the Access Router from the cache router for decapsulation and forwarding the data packets to one or more of the user devices.

3. The method of claim 1, further comprising outputting a message from a gateway router of the internet service provider network specifying to an access router of a metro transport network an internet protocol network address prefix advertised by the access router on behalf of the internet service provider network.

4. The method of claim 3, wherein the message comprises a border gateway protocol routing protocol message enhanced to specify network address reachability information advertised by the access router.

5. The method of any one of claims 1 to 4, wherein receiving an Ethernet virtual private network routing advertisement informing of network address reachability information for the user device comprises receiving a routing protocol message of routing type 5 carrying the Internet protocol network address prefix or of routing type 2 carrying a user's MAC address and Internet protocol address.

6. A communication system, comprising:

a metro transport network between a group of user devices and at least one internet service provider network, authenticating said user devices and assigning corresponding layer 3 addresses to said user devices from corresponding internet protocol network address prefixes assigned to said internet service provider network,

wherein said MAN provides layer 2 packet switching for transferring network packets between said Internet service provider network and said user device,

wherein the metro transport network comprises at least one access router connected to the user device by one or more access links, at least one cache router coupled to a local content cache of the metro transport network, and at least one network provider edge router disposed between the internet service provider network and the metro transport network and operable to carry traffic;

wherein said access router, said cache router, and said network provider edge router establish an Ethernet virtual private network within said metro transport network,

wherein the access router outputs an Ethernet virtual private network route advertisement to the cache router within the Ethernet virtual private network, the Ethernet virtual private network route advertisement informing the user device of network address reachability information on behalf of the Internet service provider network,

the cache router of the metropolitan area transmission network outputs a routing protocol routing advertisement, and the routing protocol routing advertisement informs the router of the internet service provider network of the network address reachability information of the local content cache of the metropolitan area transmission network; and is

Wherein, in response to a content request redirected from the internet service provider network and based on the ethernet virtual private network routing advertisement from the access router, a cache router of the metro transport network forwards content from the local content cache to the access router over the ethernet virtual private network for delivery to one or more customers.

7. The system of claim 6, wherein the cache router of the metro transport network is configured to forward content by encapsulating data packets sent to one or more customers and traversing the data packets through the ethernet virtual private network enabled metro transport network from the cache router into the access router for decapsulation and delivery to one or more of the customer devices.

8. The system of claim 6 or 7, wherein the access router is configured to output the Ethernet virtual private network routing advertisement by constructing and outputting a Border gateway protocol routing protocol message of routing type 5 carrying an Internet protocol network address prefix or of routing type 2 carrying a MAC/IP address combination.

9. The system of claim 6, further comprising a gateway router of the internet service provider network configured to output a message to an access router of the metro transport network specifying the network address reachability information of the user device notified by the access router on behalf of the internet service provider network.

10. The system of claim 9, wherein the message comprises a border gateway protocol routing protocol message enhanced to specify network address reachability information advertised by the access router.

11. A cache router of a metro transport network, said metro transport network being located between at least one internet service provider network and a set of user devices, wherein said internet service provider network authenticates said user devices and assigns respective layer 3 addresses to said user devices, said cache router comprising:

a control unit having at least one processor coupled to a memory,

wherein the control unit executes software configured to establish an Ethernet virtual private network with one or more access routers within the metro transport network and at least one network provider edge router disposed between the Internet service provider network and the metro transport network and operable to carry traffic, and

wherein the control unit is configured to receive an Ethernet virtual private network routing advertisement from the access router, the Ethernet virtual private network routing advertisement specifying network address reachability information on behalf of the Internet service provider network,

wherein the Ethernet virtual private network routing advertisement specifies network address reachability information for the user device and indicates that the user device of the Internet service provider network is reachable through the access router;

the cache router of the metropolitan area transmission network outputs a routing protocol routing advertisement, and the routing protocol routing advertisement informs the router of the internet service provider network of the network address reachability information of the local content cache of the metropolitan area transmission network; and is

Wherein, in response to a content request redirected from the internet service provider network, a cache router of the metro transport network forwards content from the local content cache to the access router for delivery to one or more customers via the ethernet virtual private network.

12. The cache router of claim 11, wherein the access router is configured to output the ethernet virtual private network routing advertisement by constructing and outputting a border gateway protocol routing protocol message that routes a type 5 layer 3 network address prefix or a routing type 2 carrying a MAC/IP address combination.

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