EP2564570A1

EP2564570A1 - Methods and devices having a key distributor function for improving the speed and quality of a handover

Info

Publication number: EP2564570A1
Application number: EP11715180A
Authority: EP
Inventors: Thomas Gamer; Matthias Roth; Michael Bahr; Christian Schwingenschloegl
Original assignee: Siemens Enterprise Communications GmbH and Co KG
Current assignee: Unify GmbH and Co KG
Priority date: 2010-04-26
Filing date: 2011-04-15
Publication date: 2013-03-06
Also published as: US20120284773A1; CN102474522A; WO2011134608A9; DE102010018285A1; WO2011134608A1

Abstract

The invention relates to a network access node (MAP1) for a terminal (STA) that is wirelessly incorporated into the network, comprising: a) a memory (1) having at least one first key and address codes of second access nodes (MAP2,..., MAPn) for the terminal (STA), b) at least one data communication unit (2) for exchanging data with the second access nodes, c) connected to the memory (1) and the data communication unit (2), a processor (3) having functions for: d) deriving second keys, among them second keys for securing the connection between the terminal (STA) and the second access nodes, from the first key, e) securely associating the terminal using a key derived from the first key, f) in response to the execution of function d), sending the second keys for securing the connection between the terminal (STA) and the second access nodes by the data communication device via secured connections and with addressing by the address codes, characterised in that the second keys further comprise the key used for step e).

Description

Network access node with key distribution function

The invention relates to a network access node for a wirelessly integrated into the network terminal, a network that at least one of these

Network access node includes, a method for

Preparation of a handover process in this network, a method for configuring a configuration of this network and a computer program with instructions according to the inventive method.

The invention can be used in a voice-over-IP application and a video-on-demand application,

in particular in a local network, in particular WLAN. The invention can be used especially in mesh networks. Wireless networks are becoming increasingly popular in the home and office space. A basic standard for such networks is the IEEE 802.11 standard. Mesh networks are wireless networks with flexible topology. Meshfähige

Nodes of a mesh network have features to detect topology changes or to set up fallback routes.

For the Internet, real time applications such as Voice over IP (VoIP) or Video on Demand (VoD) known.

Endpoints of real-time communication are usually this way called "stations" or "clients", ie non-mesh terminals.

For integration into a meshnetz these must

Associate terminals with access nodes of the meshnetzes. In response to topology changes of the meshnetwork or movements of a terminal over several radio cells of the access nodes of the meshnetwork, handover operations are provided in which the terminal associated with an access node recombines with another access node of the meshnetwork.

The speed of handover is critical to the quality and performance of such real-time applications using wireless connections, especially for real-time applications. In order to enable non-meshed terminals real-time capability, handover operations should therefore be carried out from one access node to another as quickly as possible and without packet losses

expire.

802.11 networks use fixed access nodes that usually communicate with each other over wired links.

In mesh networks communication is to

Key distribution between the access nodes due to the wireless transmission unreliable as in wired communication and has due to the multi-hop communication increased delay. This results in slower handover operations in Meshnet zen. Due to the mobility of both mesh nodes and terminals, handover operations in mesh networks also occur more frequently. Both the mobility of mesh nodes and terminals can result in an increased number of handover operations. In mesh networks access nodes operate via a wireless medium error-prone communication, which is also usually carried out over several wireless hops. A request for a PMK-Rl key by a

Access node, with which a terminal needs to re-associate, therefore takes time and the handover experiences a delay.

The IEEE 802. RF standard shows handover mechanisms in 802.11 networks and is documented in the IEEE Trial Use Recommended Practice for Multi-Vendor Access Point

Interoperability via to Inter-Access Point Protocol

Across Distribution Systems Supporting IEEE 802.11

Operation, 2003. It does not contain mechanisms for

Optimization of a handover process.

The 802.21 standard concerns communication and

Carrying out a handover between heterogeneous networks and documented in Standard for Media

Independent Handover Services, IEEE Computer

Society / Local and Metropolitan Area Networks, Draft

802.21 standard, 2004.

An acceleration of authentication after initiating a handover is shown by Bruce McMurdo, Cisco Fast Secure Roaming, 2004. To speed up handover operations, Catherine Rosenberg, Edwin KP Chong, Hosame Abu-Amara, Jeongjoon Lee, Efficient Roaming over Heterogenous Wireless Networks, Proceedings of the WNCG Wireless Networking Symposium, Catherine Rosenberg, 2003, will provide authentication with the new access node already performed while the station is still connected via the second interface with the old access node.

Standardization for fast handover operations in 802.11 wireless networks is shown in Draft Amendment to Standard for Information Technology - Telecommunications and Information Exchange between

Systems - LAN / MAN Specific Requirements - Part 11:

Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications: Amendment 2: Fast BSS

Transition, D2.0, March 2006. To optimize handover, a special key hierarchy is used in 802.11 wireless networks in accordance with the IEEE 802.11r standard. These

standardized variant of the key distribution is such that a security relationship with the PMK-R0 keyholder must first be requested from the Mobility Domain Controller (MDC) before a PMK-Rl key can be transmitted for the handover process. This delays the handover process. FIG. 2 schematically shows a communication in a handover process according to the IEEE 802. Ilr standard

illustrated. Each access node calculates after its initials

Login within a Mobility Domain a PMK-R0 key. He establishes a security relationship with a PMKRO keyholder with the help of a Mobility Domain Controller MDC. This will be more successful

Authentication from the negotiated master key

and is stored on the access node MAPI, at which the new access node MAP2 logs on for the first time. This access node MAPI is also called PMK-R0 keyholder. The PMK-RO key is then used to derive a so-called PMK-RI key, which forms the basis for protecting communication with the PMK-RO key

Access node MAP2 forms.

The new mesh-capable access node MAP2 receives a

Authentication Request from the terminal STA, whereby the handover process is initiated. If the terminal STA initiates the handover procedure in a step S1, then the new access node MAP2 establishes a service using the mobility domain controller MDC in a step SO

Security relationship with the access node MAPI, which is PMK-RO keyholder. In this he asks in a step S2 a "own" PMK-Rl-key, which as a basis for the protection of the new

Communication relationship between terminal STA and new access node MAP2 is used. For this purpose, the access node MAPI forwards the PMK-RO key in a step S3 PMK-Rl key and sends in a step S4 the PMK-Rl key to the new access node MAP2. The new access node MAP2 then sends an authentication response to the terminal in a step S5, followed by the terminal in a step S6 with the new

Access node MAP2 associated with the handover process without re-authenticating the terminal

can be completed successfully.

The object of the invention is the speed

and / or quality of a handover operation between first and second and new access nodes for a wirelessly integrated into the network terminal.

The invention relates to a network access node for a wirelessly integrated into the network terminal, comprising:

a) a memory device having at least a first key and address codes of second access nodes for the terminal in the network,

b) at least one data communication device for data exchange with the second access node,

c) associated with the storage device and the data communication device, one or more processors having functions for:

d) derive second key, including second

Key to secure the connection between the

Terminal and the second access node, from the first key, e) secure association of the terminal under

Using a key derived from the first key,

f) in response to the execution of function d), sending the second key to secure the

Connection between the terminal and the second

Access node through the data communication device with addressing by the address codes over secure connections.

According to the invention, the second keys further comprise the key used for step e).

Preferably, the first key is a PMK-R0 key and the second keys are PMK-Rl keys.

The invention thus enables distribution of second keys such as PMK-Rl keys to adjacent ones

Access node of the network access node or even all access nodes with a shared with the network access node mobility domain. Thus, in the case of a handover, no additional delay is caused by the

Request of required keys generated. The network access node is advantageously a node of a Meshnet zwerks.

The second key may be proprietary features of the

Encoding terminal, in particular a MAC address. The first and second keys are in particular pairwise symmetric keys, eg PMK-R0 and PMK-Rl keys. The address codes are in particular address codes of all

Access nodes having a common mobility domain with the network access node.

The address codes can also address codes of second

Access nodes whose radio cells cluster with a radio cell of the network access node for part of the network. Second keys can thus be distributed to neighbors of the network access node so that the PMK-Rl keys are distributed to neighboring ones

Access node of the network access node is advantageously caused a relatively low bandwidth requirement. The number of second keys to be derived and distributed is thus relatively small for the network access node.

The sending of PMK-Rl keys could, for example, be realized by means of EAPOL key frames. The actual frame format for key exchange is not part of the IEEE 802.11r standard.

When distributing the PMK-Rl keys to all access nodes with one common to the network access node

Mobility domain becomes in a Meshnetzwerk when using a reactive or hybrid routing protocol

advantageous for the distribution of PMK-Rl keys no not negligible routing overhead and causes little computational effort to generate keys for all access nodes of a mobility domain.

While the terminal is active in a mobility domain, the network access node according to the invention optionally additionally distributes a part of the derived second key to access nodes which are added to the mobililty domain and updates the latter

Address codes in its memory device. For this purpose, in the network adapted to this process communication between an authentication server and the

Serving network access nodes.

An inventive meshnetwork includes

at least one network access node according to the invention and a plurality, in particular more than 3, in particular more than 4, in particular more than 9 of the second

Access nodes,

if necessary forwarding node without

Network access function for the terminal.

The network according to the invention is here by secured connections under the network access node and second access node, optionally via the

Forwarding node, constructed and at least one, preferably a Mobility Domain Controller and

at least one, preferably one

Authentication server. In the Meshnetzwerk invention with the

The network access node according to the invention, the cluster is defined in particular such that between the

Network access node and every second access node with a radio cell in the cluster a connection over a maximum of three, in particular a maximum of two, in particular a maximum of one node is constructed.

At least one part, especially all of the second

Access nodes can according to the invention

Be network access node.

For sending at least some of the second keys, the network preferably has a function for

g) redefining the cluster in response to performing the association of the terminal with the network access node by updating the cluster

Address codes in the network access node.

A network access node according to the invention as a PMK-R0 keyholder can then be provided with functions to determine neighboring access nodes by means of a metric to be defined and send them their PMK-RI key, which functions are executed specifically after each handover procedure also neighbors of a new access node in the case of one

handovers over the PMK-Rl keys and thereby minimize the delay. An example of such a neighborhood metric is then such that all access nodes participating in the network no more than one hop from the handover process Network access nodes are removed, are defined as neighbors. Other useful maximum values for the number of hops are, for example, two or three.

In the network according to the invention, the

Forwarding nodes, i. Mesh knot without

Access node functionality, also called forwarders, forward data to improve connectivity in the network, especially the mesh network. Maximum numbers for the number of hops can be adjusted to increase the number of hops in the network

Presence of forwarding node between access node is caused.

Maximum values for the number of hops can be one

Be adapted situation in which the terminal can communicate with two network access nodes, this

However, network access nodes do not communicate with each other directly wirelessly, i. if a client is in the middle between two access nodes and sees both, but the access nodes are not each other.

Inventive methods result from carrying out the above-described functions of network access nodes and / or networks according to the invention. Specifically, methods according to the invention are defined in the method claims.

The network according to the invention has connections under access nodes of the network with security relationships. In one embodiment, at least one Network access node in the network according to the invention as a node with functions of

Authentication server and / or the mobility domain controller to be trained, especially in smaller mesh networks hardware resources such as a

To save authentication servers and provide an excellent node instead.

The enabled by the invention

Key distribution strategies are the special ones

Adapted properties of mesh networks compared to 802.11 networks, reducing delays in requesting the PMK-RI key needed for a handover operation. This can accelerate handover operations in mesh networks and

Real time applications, such as Voice over IP, better supported. Key distribution and

Key management can be optimized depending on a scenario in the network.

Aspects and exemplary embodiments of the invention will now be described with reference to the figures, in which: FIG. 1 schematically illustrates a network access node

illustrated;

FIG. 2 schematically illustrates communication in a handover process in accordance with the IEEE 802. Ilr standard; FIG. Fig. 3 schematically illustrates a communication according to the invention;

Fig. 4 illustrates a network of the invention in connection with a terminal.

In the network access node of the invention shown in Fig. 1, a processor 3 via a bus 4 with a memory device 1 and a

Data communication device 2 connected. The

Storage means stores a PMK-RO key and address codes of second access nodes MAP2, MAPn of a network with the network access node. Fig. 4 shows a mesh network of the invention in connection with a terminal STA. The network has five mesh-ready access nodes MAPI, MAP2, MAP3, MAP4, MAP5 and three

Forwarding nodes MP1, MP2, MP3, one

Authentication server AS and a Mobility Domain Controller MDC. There is not one with the network

Meshable mobile station as terminal STA in

Connection .

FIG. 3 illustrates the communication in the network shown in FIG.

All mesh-capable access nodes MAPI, MAP2, MAP3, MAP4, MAP5 have already been authenticated at the authentication server AS and are therefore an active part of the

shown meshnetzes. The station STA is initially authenticated via the access node MAPI, where this forwards the authentication information to the authentication server AS. Of the

Authentication server AS performs the

Checking the access authorization by and generates a successful authentication

Master Key. It then transmits this to the initial access node MAPI, which derives the PMK-R0 key therefrom. In its function as a PMK-R0 keyholder, the initial network access node MAPI locally stores the PMK-RO key in its memory device 1. The network access node MAPI derives four further PMK-Rl keys for the access nodes MAP3, MAP2, MAP4 and MAP5 directly after the authentication of the STA. The PMK-Rl key forms the basis for the protection of the communication relationship between the initial network access node MAPI and now with the

Meshnetzwerk associated station STA. After

Establishing a security relationship with all these access nodes using the Mobility Domain Controller MDC will transfer MAPI's PMK-RI keys to the

respective access nodes MAP3, MAP2, MAP4 and MAP5. If the station to a later

Time a handover, e.g. to the new

Access node MAP4, initiates, this already has the appropriate PMK-Rl key. The new access node MAP4 can thus handle the handover without further

Communicate with the mobility domain controller MDC and the network access node as the PMK-RO keyholder MAPI. In the network illustrated in FIG. 4, a method illustrated in FIG. 3 is accordingly provided with the steps:

510 establishment of security relationships under the initial network access node MAPI and all further access nodes MAP2, MAP3, MAP4, MAP5 whose address codes are received by the mobility domain controller MDC and stored in the memory device 1 of the initial network node MAPI, the access nodes MAPI, MAP2, MAP3, MAP4, MAP5 are authenticated with the authentication server AS,

511 authentication of the terminal STA is initiated at the initial network access node MAPI at

Execution of the steps:

Sending authentication information from the terminal via the initial network access node MAPI to the authentication server AS,

Verification of the authentication information by the authentication server AS and subsequent generation of the master key,

Sending the master key to the initials

Network access node MAPI,

Derivation of the PMK-RO key from the

Master key through the initial network node (MAPI) and storing the first key in the

Memory device 1 of the initial

Net access node,

After deriving a PMK-Rl key from the PMK-R0 key for the terminal STA and thus secure association of the terminal, the steps are carried out: 512 deriving further PMK-Rl keys through the initial network access node MAPI and

513 Sending the other PMK-Rl keys

at least the access points MAP2, MAP3, MAP4, MAP5.

Alternatively, the initial network access node does not transmit the PMK-Rl key of station STA to all other active ones after the initial authentication

Access node of the mobility domain, but only to

adjacent access nodes, for example, a maximum of n hops away from him, where n is 1 to 3, preferably 2. The initial access node MAPI then calculates the PMK-Rl key directly after the initial authentication of the station STA, for example for the adjacent access nodes MAP3 and MAP4 and transmits them to them. In this distribution strategy too, a later handover of the station to the new access node MAP4 can be carried out without further communication with the MDC and the PMK-R0 keyholder. However, following a successful handover operation, the access node MAPI as the PMK-RO keyholder must be notified so that it can derive another PMK-RI key and distribute it to further access nodes adjacent to the new access node MAP4. In the above example these are the access nodes MAP2 and MAP5.

LIST OF REFERENCE NUMBERS

1 storage device

2 data communication device

3 processor

4 BUS

AS authentication server

STA terminal

MAPI initial network access node

MAP2, ... MAPn second access node

MP1, MP2, MP3 forwarding node MDC Mobility Domain Controller

Claims

claims

A network access node (MAPI) for a wireless network-attached terminal (STA), comprising:

a) a memory device (1) with at least a first key and address codes second

Access point (MAP2, MAPn) for the terminal (STA) in the network,

b) at least one data communication device (2) for data exchange with the second access node, c) in connection with the

Memory device (1) and the

Data communication device (2), one or

several processors (3) with functions for:

d) deriving second key, including second key for securing the connection between the terminal (STA) and the second access node, from the first key,

e) securely associating the terminal using one of the first key

derived key,

f) in response to the execution of

Function d), sending the second key to

Securing the connection between the terminal (STA) and the second access node through the

Data communication device via secured

Connections and with addressing by the

Address code,

characterized in that the second

Keys further comprise the key used for step e). Network access node (MAPI) according to claim 1, characterized in that the network access node is a node of a mesh network.

Network access node (MAPI) according to claim 1, characterized in that the second key encodes proprietary features of the terminal (STA), in particular a MAC address.

Network Access Node (MAPI) according to one of

preceding claims, characterized in that the first and second keys are pairwise symmetric keys.

Network access node (MAPI) according to one of claims 2 to 4, characterized in that the address codes are address codes of all access nodes in the network having a common mobility domain with the

Network Access Node (MAPI).

Network access node (MAPI) according to one of claims 2 to 4, characterized in that the address codes address codes of access node among the second

Access nodes are whose radio cells with a

Network Access Point (MAPI) radio cell to cluster a portion of the network.

Network comprising at least one network access node (MAPI) according to one of the preceding claims and

a large number, in particular more than 3,

in particular more than 4, in particular more than 9, of the second access nodes,

optionally forwarding nodes (MP1, MP2, MP3),

the network being secured by links under the network access nodes and second

Access node, possibly over the

Forwarding node (MP1, MP2, MP3) is constructed and secured connections to at least one, preferably a Mobility Domain Controller (MDC) and at least one, preferably one

Authentication server (AS).

The network of claim 7, wherein the

Network Access Node (MAPI)

The network access node of claim 6 and the cluster is defined such that between the

Network Access Node (MAPI) and every other

Access node (MAP2, ..., MAPn) with a radio cell in the cluster a connection over a maximum of three, in particular a maximum of two, in particular a maximum of one access node is constructed.

Network according to claim 7 or 8, characterized

characterized in that at least one part,

in particular all of the second access nodes (MAP2, ..., MAPn) are network access nodes according to one of claims 1 to 6. A network according to claim 9, comprising a function of g) redefining the cluster in response to execution of the function e) in one

Network access node (MAPI) according to claim 6 by updating the address codes in the

Network access node.

Method for preparing a handover process in a network according to one of Claims 7 to 10 with an initial network node (MAPI) according to one of Claims 2 to 6,

wherein all the second access nodes whose address codes in the memory device (1) of the initial

Network nodes (MAPI) are stored, are authenticated to the authentication server and an authentication of the terminal (STA) is initiated at the initial network node by performing the steps:

Sending authentication information from the terminal via the initial network node to the authentication server (AS),

Verification of the authentication information by the authentication server (AS) and subsequent generation of a

Root cutis,

- Sending the root key to the initials

Network node (MAPI),

Derivation of the first key from the

Root key through the initial Network node (MAPI) and storing the first key in the storage device (1) of the initial network node,

with the initial network node (MAPI) performing the following steps:

d ') deriving a second key from the first key and

e) securely associating the terminal using the second key, and in response to the execution of step d '), the characterizing steps:

d) deriving further second keys by the first network node,

f) sending the further second keys to at least one part, in particular all second access nodes of the network.

The method of claim 11, wherein the initial

Network node (MAPI) a network node after

Claim 5 and the other second key in step f) to each access node of the

Network having a common mobility domain defined by the Mobility Domain Controller (MDC) with the initial network node.

The method of claim 11, wherein the initial

Network node (MAPI) a network node after

Claim 6 and the other second key in step f) to each second access node (MAP2, ..., MAPn) whose radio cells form the cluster.

A method of configuring a network according to claim 10, comprising carrying out the method according to claim 13 and characterized by

Execution of the function g).

Computer program characterized by instructions according to a method according to any one of the claims