Abstract:
An access node connected to end-users, routers, and a DHCP-server. The end-user defines desired services provided via the routers. A purpose is to automatically provide simultaneous access to services via two or more of the routers, although the end-user simultaneously handles only one router. The connections are secure. The end-user requests one of the services. The access node identifies the end-user and sends a corresponding request to the DHCP-server, which dynamically allocates addresses to the end-user and to all the routers for the desired services. The access node snoops the addresses in a DHCP option message from the DHCP-server, resolves the router addresses, stores IP router addresses and IP MAC addresses in a memory and sets MAC addresses in MAC filters. An option reply with one router is sent to the end-user, which after request for one service, reaches all the services stored in the memory.

Description:
TECHNICAL FIELD 
   The present invention refers to providing multiple services in an access system. 
   BACKGROUND 
   A user of services provided via telecommunication networks often needs to have simultaneous access to a plurality of service providers. It is also essential that the connections set up are secure and are unable to use for other subscribers than the user in question. 
   A mechanism known as MAC-Forced Forwarding MFF ensures secure connections. The mechanism ensures that all end-users connected to a specific Service VLAN inside an Ethernet Aggregation Network are allowed access only to a default gateway and not directly to each other or to other edge nodes attached to the service VLAN. The MFF mechanism also permits an access node, to which the end-users are connected, to dynamically learn the address of the mentioned default gateway to allow access to for each end-user IP host. This is done by the access node snooping a DHCP reply to the end-user IP host after a DHCP request for an IP address from the end-user. The MFF mechanism was designed with single-edge access per IP host in mind, i.e. for access to one default gateway. The MFF mechanism is more closely described in T. Melsen, S. Blake: “MAC-Forced Forwarding: A Method for Traffic Separation on an Ethernet Access Network”, available on the web at draft-melsen-mac-forced-fwd-03. 
   Support for a general multi-edge access, i.e. simultaneous access to the plurality of service providers, requires the end-user IP host to be able to access a multiple number of edge nodes simultaneously. This enables so called true triple-play scenarios, in which a single end-user IP host can access e.g. high-speed Internet service, Voice over IP service and IPTV service simultaneously, delivered by separate edge nodes. This is made possible by provisioning the edge nodes IP addresses statically in the access node. An operator of the network writes the addresses manually in the access node. The method is simple and secure but is relatively cumbersome. 
   SUMMARY 
   The present invention is concerned with a main problem to provide for an end user to have simultaneous and secure access to multiple routers. Manual assignment of multiple IP-addresses to the end-user is a part of the problem. 
   A further problem is that the set up connections are secure and are available only for the end-user in question. 
   Still a problem is to prevent said end-user to get access to a service that is not allowed for the user. 
   The problem is solved by an access node snooping and storing IP-addresses of the routers the end-user is allowed to access. The routers IP addresses are resolved into MAC addresses by the access node using standard Address Resolution Protocol ARP. The IP addresses of the allowed routers are communicated dynamically to the access node. 
   Somewhat more in detail the problem is solved in that the access node receives a request concerning a service that the end-user is entitled to. The access node sends the request to a server and receives a reply with a dynamically assigned end-user host IP address, and IP addresses to routers that should be accessible by the user. The access node reads the reply, saves the routers IP address and resolves the routers MAC addresses. The access node sends a reply to the end-user with at least one of the IP router addresses. 
   A purpose of the present invention is to provide a more flexible access scheme, e.g. for triple play scenarios, by allowing end-users IP hosts to have simultaneous access to multiple routers. 
   Another purpose is to avoid manual configuration of accessible routers and instead provide dynamic configuration. 
   A further purpose is to give IP hosts, which can only handle a single router, access to multiple routers. 
   Still a purpose is to make access unable to a service for a not entitled end-user. 
   Still another purpose is to provide secure connections. 
   The invention has an advantage to provide a more flexible access scheme by allowing end-users IP hosts to have simultaneous access multiple routers. 
   Another advantage is that manual configuration of accessible routers is avoided. 
   A further advantage is that IP hosts, which can only handle single routers, are given access to multiple routers. 
   Still an advantage is that abusive use of services is avoided. 
   Still another advantage is that secure connections are provided. 
   The invention will now be described more closely with the aid of embodiments and with references to enclosed figures. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a view over an access system; 
       FIG. 2  shows a view over an alternative access system; 
       FIG. 3  shows a flowchart of the method; 
       FIG. 4  shows a block schematic over a reply message, and 
       FIG. 5  shows a block schematic over a reply message. 
   

   DETAILED DESCRIPTION 
     FIG. 1  shows a view over an access system ACC 1 . The system has an access node EDA 1  to which end-users EU 1  and EU 2  are connected. Three service provider access routers R 1 , R 2  and R 3 , providing services to the end-users, are connected to the access node. The first router R 1  is an IP router in an Internet VLAN denoted IV 1 . The second router R 2  is a voice gateway in a voice VLAN denoted VV 1 . The third router R 3  is a video server in a video VLAN denoted VV 2 . The three routers R 1 , R 2  and R 3  have IP MAC addresses MACX, MACY and MACZ respectively. Also a DHCP server DH 1 , in a DHCP VLAN denoted DV 1 , is connected to the access node EDA 1 . 
   In the access node are arranged MAC filters MX, MY and MZ, which only let through the respective IP MAC addresses MACX, MACY and MACZ. Also MAC filters MY 2  and MZ 2 , which only let through the respective IP MAC addresses MACY and MACZ, are arranged in the access node. The access node also has memories TAB 1  and TAB 2  as will be more closely described below. A control function CU 1  controls the working of the access node EDA 1 . As an alternative the DHCP server DH 1  can be connected to the first router R 1 , as is shown in dashed lines in the figure. 
   The DHCP server DH 1  has an address pool AP 1  with end-user IP host addresses, which can be allocated dynamically. 
   The end-users EU 1  and EU 2  can point out which of the services provided via the routers R 1 , R 2  and R 3  they desire to have access to. The end-user EU 1  has determined a set of services consisting of services from the Internet VLAN IV 1 , the voice VLAN VV 1  and the video VLAN VV 2  as shown by dotted lines in the figure. The end user EU 2  has determined a set of services from only the Internet VLAN IV 1  and the voice VLAN VV 1 , which also is shown by dotted lines. The services are initially selected by the respective end-user and are ordered via any conventional means, e.g. by a telephone call to an operator or via a web page. 
   In the present embodiment of the method the Dynamic Host Configuration Protocol DHCP and its different options are utilized. In short the DHCP protocol allocates IP addresses to the end-user hosts and allocates ways out of the local net via the routers. More information is to be found on the web at www.ietf.org, number RFC 3442. 
   When the end-users desire access to the services provided via the edge access routers R 1 , R 2  and R 3 , they utilize the access system ACC 1  in the following manner. As an example the end-user EU 1  wants a service on the Internet IV 1  provided via the router R 1 . The end-user EU 1  therefore sends a corresponding DHCP request RQ 1 . The control function, which listens to the traffic, recognizes the DHCP request. The access node EDA 1  is configured such that it can accept the request. The access node receives the request RQ 1  and the control function CU 1  completes it with a DHCP option  82 , which identifies the end-user EU 1  with the aid of its port identifier. The access node EDA 1  then transmits the completed DHCP request, denoted by RQ 2 , to the DHCP server DH 1 . 
   When the DHCP server DH 1  receives the DHCP request RQ 2  it dynamically allocates an end-user IP host address IPH from the address pool AP 1 , and accessible routers R 1 , R 2 , R 3 . Access to these routers were once ordered by the end-user EU 1  as described above. The server DH 1  then forms a DHCP reply message RP 1  which includes a DHCP option  121 . This option  121  indicates which addresses the different routers R 1 , R 2  and R 3  have and the networks that can be reached via each router. The DHCP reply RP 1  is transmitted to the access node EDA 1 . 
   The access node EDA 1  receives the DHCP reply message RP 1  and the control function snoops the content in the message. It then makes an ARP request for the MAC addresses of the routers and saves the content in the memory TAB 1  as appears from the table below. 
                                                                                     Router R1: IP1: MACX                IP Router IPN1   0.0.0.0/0            Router R2: IP2: MACY                IP Router IPN2   172.10.0.0/16               192.168.10.0/24            Router R3: IP3: MACZ                IP Router IPN3   10.11.12.0/24               10.11.15.0/24               122.10.0.0/16                        
The IP router addresses for the routers R 1 , R 2  and R 3  are denoted in the table by IPN 1 , IPN 2  and IPN 3  respectively.
 
   The control function CU 1  of the access node EDA 1  now can set the IP MAC addresses MACX, MACY and MACZ in the respective MAC filters MX, MY and MZ. The end-user EU 1  therefore only can reach the routers R 1 , R 2  and R 3  and not e.g. the end-user EU 2 . This means that the connections in the access system ACC 1  are secure and also that the end-users can utilize only the services which they are entitled to. 
   The access node has to send the DHCP reply to the end-user to make the requested service available. Now a problem arises that many end-users cannot handle the DHCP option  121  with several IP router addresses but can only handle the DHCP option  3  with one IP router address. Therefore the control function CU 1  of the access node EDA 1  translates the DHCP option  121  in the reply message RP 1  into DHCP option  3  with the only network address IPN 1  before it sends a DHCP reply message RP 2  to the end-user EU 1 . 
   The end-user EU 1  receives the message RP 2  with the IP router address IPN 1  and makes an ARP request ARP 1  with this address. When the access node EDA 1  receives this request it compares the address IPN 1  with the content in the above memory TAB 1 . If the requested IP router address coincides with the saved IP router address in the table TAB 1  the access node gives the end-user EU 1  access. This access is not only valid for the requested router R 1  but does also comprise access to the routers R 2  and R 3  and the services that they provide. 
   The ARP request includes not only the IP router address IPN 1  but also a MAC address. This MAC address should in the present embodiment be the address MACX, but this can be wrong router MAC address for the specific service. This depends on that the end-user EU 1  only is aware of one single MAC and router address. When end-user data packets are received by the access node, the control function CU 1  automatically corrects such an incorrect MAC address with the aid of the content of the memory TAB 1 . 
   In the same manner as described above the system allows access for the end-user EU 2  to the requested services provided via the routers R 2  and R 3 . The end-user sends e.g. a DHCP request RQ 21  for voice services. The request is received by the access node EDA 1  and the control function adds a port identifier and sends a corresponding request RQ 22  to the DHCP server DH 1 . The latter automatically and dynamically allocates an end-user IP host address from the address pool, and accessible routers R 2  and R 3 . The DHCP server forms a DHCP reply message RP 21  which includes the DHCP option  121 . When the access node receives the reply RP 21  the control function snoops the message content. The access node makes an ARP request for the routers MAC addresses and saves the information in the memory TAB 2  as appears from the table below. 
                                                                 Router R2: IP2: MACY                IP Router IPN2   172.10.0.0/16               192.168.10.0/24            Router R3: IP3: MACZ                IP Router IPN3   10.11.12.0/24               10.11.15.0/24               122.10.0.0/16                        
The control function will set the IP MAC addresses MACY and MACZ in the respective filters MY 2  and MZ 2  so that the end-user EU 2  only can reach the routers R 2  and R 3  and the services provided via them. The access node adds the DHCP option  3  to the reply message RP 21  and sends the whole as a message R 22  to the end user EU 2 . The latter then sends an ARP request ARP 2  including the IP router address IPN 2  to the access node, which makes the services provided via the routers R 2  and R 3  available to the end-user EU 2 .
 
   An alternative embodiment will be described in connection with  FIG. 2 . This embodiment is suitable for operators who use the RADIUS (Remote Authentication Dial-in User Service Protocol) protocol for authentication, authorization and accounting purposes between a BRAS (Broadband Remote Access Server) and an end-user configuration server. The BRAS comprises a RADIUS client RC 2  and the configuration server is a RADIUS server RS 2 . The figure shows a view over an access system ACC 2  with an access node EDA 2 , to which end users EU 3  and EU 4  are connected. A service provider access router R 21  is connected to the access node. In the same manner as in the previous embodiment a DHCP server DH 2  in a DHCP VLAN denoted DV 2  is connected to the access node EDA 2 . The access node also has a local DHCP server DH 3  connected to the abovementioned RADIUS client RC 2 . The latter is connected to the centrally located RADIUS server RS 2 . Compared to the DHCP-based model in  FIG. 1  the RADIUS-based model replaces the DHCP server DH 1  by the local DHCP server DH 3  and the centrally located RADIUS server RS 2 . 
   When the end-user EU 3  requests for service it will issue a DHCP request RQ 31  in the same manner as described in connection with  FIG. 1 . The request RQ 31  will be intercepted by the local DHCP server DH 3  in the access node. The control function CU 2  of the access node EDA 2  sends a RADIUS request message RQ 32  to the RADIUS server RS 2  with this information. The RADIUS message RQ 32  includes the content of the DHCP request RQ 31  and a unique identification of the end-user EU 3  by e.g. a port identifier normally used in the DHCP option  82 . The RADIUS server RS 2  dynamically allocates an end-user IP host address from the address pool, and access to relevant routers, e.g. the router R 21 . The server RS 2  then sends a reply message RP 3  providing host configuration information similar to that sent by the DHCP server DH 1  in  FIG. 1 . The reply message RP 3  is fed to the local DHCP server DH 3  and as in the previous embodiment the access node EDA 2  snoops the information in the message. The access node also saves the information in a memory TAB 3  similar to the memory TAB 1  described above. In its DHCP reply to the end user EU 3  the access node EDA 2  translates the reply message RP 3  into a reply message RP 4  suitable for end-users only supporting the DHCP option  3 . 
   In the description above the DHCP option  121  is mentioned. Originally the DHCP option is targeted towards the end-users who use it to build a list of gateways and corresponding IP subnet. However, device support for DHCP option  121  cannot be assumed in general, and static IP configuration performed by the end-user of gateways is not considered a viable solution, as already mentioned above. An alternative, described above, is to generally assume that the end-user does not support DHCP option  121  and that the access nodes EDA 1  and EDA 2  must always do the necessary frame modification and switching that enables a multi-edge architecture. 
   This implies that the access node must direct the upstream traffic to the right gateway using layer-3 switching, i.e. switching based on the destination IP address. Likewise, downstream traffic must be modified so it looks as if it all came from the default gateway, i.e. the source MAC address must be changed to that of the default gateway. 
   A variant of this layer-3 switching is to use the access node MAC address as default gateway address for all end-users. This variant has the advantage of only using a single MAC address per access node for end-user traffic. In the present description this MAC address for the access node EDA 1  is denoted MACE in  FIG. 1 . 
   In connection with  FIG. 3  the method described above will be summarized. The method starts in a step  301 , in which the end-user decides services to utilize and informs the network operator about the decision. In the example the services are provided via the routers R 1 , R 2  and R 3 . The end-user, e.g. end-user EU 1 , sends the DHCP request RQ 1  in a step  302  and in a step  303  the access node EDA 1  receives the request and recognizes it as a DHCP message. The access node completes in a step  304  the request RQ 2  with the DHCP option  82 , identifying the end-user&#39;s port. In a step  305  the access node sends the request RQ 2  to the DHCP server DH 1 , which receives it in a step  306 . In a step  307  the DHCP server dynamically allocates both the IP network address to the end-user IP host from the address pool and accessible routers R 1 , R 2  and R 3 . The DHCP server DH 1  sends the DHCP reply RP 1  to the access node in a step  308 . In a step  309  the access node resolves the IP router addresses and saves the IP router addresses and IP MAC addresses in its memory TAB 1 . The IP MAC addresses are set in the MAC filters MX, MY and MZ in a step  310 . In a step  311  the access node EDA 1  adds the DHCP option  3  to the reply RP 2  including the IP network address IPN 1  and the router IP address MACX and sends the reply to the end-user in a step  312 . Alternatively the reply RP 2  has the IP MAC address MACE of the access node itself instead of the MAC address MACX. 
   In a step  313  the end-user EU 1  makes the ARP request ARP 1  with the addresses IPN 1  and resolves this to the MAC address MACX. In a step  314  the access node EDA 1  compares the addresses in the request ARP 1  with the addresses in the memory TAB 1 . In a step  315  the access node investigates whether the IP address in the request ARP 1  and in the memory TAB 1  coincide. If not so, an alternative NO 1 , access is denied for the end-user EU 1  in step  316 . When the addresses coincide, an alternative YES 1 , the access node checks in a step  317  if the MAC address is the correct one. In an alternative YES 2  the access node in a step  318  allows the end-user access to all the routers R 1 , R 2  and R 3  providing the services which the end-user EU 1  once decided. In an alternative NO 2  the access node EDA 1  first corrects the MAC address in a step  319  before access to the routers is allowed. In a step  320  the destination MAC address and destination IP address are checked in data packets from the end-user. 
   In  FIGS. 4 and 5  are shown more in detail the reply messages RP 1  and RP 2 . As described above the access node EDA 1  receives the reply message RP 1  from the DHCP server DH 1 . The message has a code field  41  stating that it is an option  121  message, which is recognized by the control unit CU 1 . A length field  42  tells the length of the reply message. A first destination field  43  states which networks are available via the router R 1 , which is defined by its IP router address in a first router address field  44 . The message RP 1  continues with a second destination field  45  stating which networks are available via the router R 2 . This router is defined in a second router address field  46 . The exemplified reply message RP 1  has also destination- and router fields for the router R 3 , only hinted by dotted lines in the figure. 
     FIG. 5  shows the reply message RP 2  from the access node EDA 1  to the end-user EU 1 . The message has a code field  51  stating that it is an option  3  message. A length field  52  tells the length of the reply message. A router address field  53  gives the IP router address to the router R 1  providing the initially requested service.