Patent Application
20090116404
The present invention relates to topology discovery in a communication network, and more particularly, to topology discovery in heterogeneous networks.
A network can be considered as a collection of linked devices called nodes, each of which is connected to at least one other node. A node may include a switching device having wired, optical and/or wireless connections. For example, a node may be a router or switch handling packet streams, a combination router-switch handling connections and packet traffic, a hub, computer, personal digital assistant, cell phone, or set top box. A node may support a large number of information sources and receivers that dynamically exchange information, or have fixed source/receiving roles, of varying activity. Additionally, the physical layout of a network often is designed to handle an expected amount of traffic flow and required levels of accessibility and quality of service (QoS).
The physical layout and inter-connectivity of nodes significantly affect the efficiency, reliability, and overall performance of a network. Thus, a network manager must have accurate knowledge of a network's physical and logical organization to address service disruption resulting from device or link failures and to plan and implement changes to the network (e.g., enhancements, changes in load).
However, it is difficult to manually determine a network's physical and logical organization of a rapidly changing network with a large and increasing number of nodes. The volume of information for this task most often is too large and complex for a human to collect. Additionally, a network administrator is faced with the challenging task of routing information via a number of alternative inter-nodal paths to ensure connectivity and quality of service. As the number of nodes increases, so too does the number of alternative inter-nodal connection patterns.
Furthermore, the advent of IP-based next-generation network (NGN) architectures introduces additional challenges. NGN architectures converge numerous single-purpose fixed and mobile networks and services (e.g., voice, data, video and other rich media) to offer a myriad of applications (e.g., IP telephony, Web browsing, e-mail, video on demand (VoD), IPTV, gaming, and video conferencing). For instance, the different services have different requirements on the underlying network structure, such as the sensitivity of voice and video services to delay, jitter and bandwidth variations. These constraints, as well as the introduction of new hardware and protocols to support applications offered in NGN, require a high degree of management from an operator. Detecting, diagnosing and correcting localized malfunctions in NGNs become even more intricate as the number of interconnected nodes increases.
To adequately address these concerns, the network topology (i.e., the network's physical and logical organization) must be known and continually updated to account for elements such as system load, failures, effective network routing, and changes such as enhancements. Such a system analysis tool should include a way for topology synthesis and network visualization to produce a visualized network model. The visualized network model forms a basis for interpreting collected data to ensure QoS, and to produce network diagnostics and troubleshooting instructions. Additionally, the visualized network model may be used for network-planning functions based on condensing collected data and mapping the condensed data on the visualized network model. The use of a distributed tool (software or protocol) is necessary as the volume of information would be enormous.
The discovery of topology is a software-based tool (and may be distributed through the network) that extracts information of the network automatically and derives the network topology from this information. The best discovery tools would be capable of precisely determining the elements of layer-3 topology (e.g., logical level, router interconnections) and layer-2 topology (e.g., switches, bridges and host stations) and on a continuous basis so that changes occurring in the network are directly identified.
Known techniques of topology discovery differ between logical and physical topology. With respect to logical topology, three steps are generally used. The first step involves sending packets throughout the network to find routers (e.g., Ping and Traceroute). The second step involves grouping multiple IP addresses into nodes representing routers. The last step involves identifying and locating the routers found. Sends can be made by brute force (i.e., by questioning all possible routers), or by target survey (only routers most likely to belong to the network). To extract good information from the results of such interrogations, redundant results coming from two different requests must be eliminated, aliases of the routers must be resolved (i.e., to associate IP addresses of the various interfaces of a router in only one node), and routers should be identified and annotated (i.e., determine which router among the routers discovered belong to the network considered, if required to find their geographic positions and their roles in the network). The Domain Name System (DNS) is generally helpful in this regard.
However, known solutions of logical topology discovery have limitations and drawbacks. For instance, the tool Ping is used to determine whether a machine is active or not. With this intention, the ping command sends an ICMP packet to a machine. If the ping message is answered, the machine is determined to be active. Broadcast Ping is an alternative of Ping and functions by sending ICMP packets to multiple addresses by broadcast. If a machine forms part of the field of the broadcast, it will answer and the sender will receive responses from all the machines of the group. While this is useful in the determination of a network under a host, Broadcast Ping it is not universally supported.
The DNS stores a great quantity of information on the nodes of the network. The service provided by all DNS servers translates hostnames to IP addresses. While the reverse is also possible, it is not always available for reasons of safety.
The Traceroute tool makes it possible to know which routers a packet passed through on the way to its destination. While this method makes it possible to discover the network, use of Traceroute has intrinsic limitations with respect to discovery of topology. For example, it does not detect unused links in a network, it does not expose the redundancy or the dependence of links (several IP links in same fiber) and it does not discover the multi access links.
Simple Network Management Protocol (SNMP) is a protocol that makes it possible to question a machine at its location in the network. For example, one can question a router to determine what machines are connected to that router. SNMP is primarily used to obtain the contents of the Management Information Base (MIB) stored by devices at each node of the network. The MIB is an information base, which may be defined by the RFC 2922, and should be present in each interconnection device. It should contain information about each port of the device, including information from endpoint devices connected to those ports. Techniques used to discover physical topology generally use SNMP and the Management Information Base II (MIB II). However, SNMP cannot be supported in certain networks, and its use is restricted within the majority of networks that do support it.
Techniques used to discover physical topology fall in two categories: passive and active. Passive techniques monitor the normal behavior of the network to infer the topology while active techniques introduce and track probe packets to discover the topology. Each of these categories will now be described.
Passive solutions include algorithms based on address forwarding tables (AFTs). In a switch, each port maintains an AFT that keeps the Media Access Control (MAC) addresses of packets it has received. If the switch supports SNMP, the AFT is stored in the entry “mib2-dot1bridge-dot1dTp” of the MIB-II. Several solutions try to continually use this table to deduce the topology of the network. Some assume that the AFT table is complete and available at all the interfaces of the nodes, but this is generally not the case. Consequently, such solutions cannot account for the switches and other connective elements of the network that do not collaborate, namely, which do not support SNMP.
Algorithms based on the Spanning Tree Protocol (STP) record information of the tree of connectivity produced by the STP by listening to BPDU (Bridge Protocol Data Units) packets sent periodically by the switches. Algorithms are then applied to calculate topology. Unfortunately, not all elements of the network support STP, and some of those that do support STP do not send BPDU packets, which would often make these types of solutions invalid in heterogeneous networks.
Algorithms based on traffic compare the traffic in bytes on all the ports and carry out the best possible approximation of a connection between two ports. These algorithms are costly, require much time to calculate the result, and have difficulty functioning in broad networks. They also necessitate the support of SNMP by all the elements of the network, which is not necessarily the case.
Active solutions try to discover topology by injecting packets of discovery (i.e., probe packets) in the network while basing themselves on the normal operation of the routing. The goal of these solutions is to circumvent the limitations presented by the use of SNMP, in particular, the availability of partial information in MIBs and non-support of SNMP by several equipment networks. Protocol owners and the standards use the active approach. Table 1 lists the principal protocols owners available on the market.
The Link Layer Discovery Protocol (LLDP) is a layer 2 protocol specified in the IEEE standard 802.1AB-2005, which allows stations attached to an IEEE 802® LAN to advertise, to other stations attached to the same IEEE 802 LAN, the major capabilities provided by the system incorporating that station, the management address or addresses of the entity or entities that provide management of those capabilities, and the identification of the station's point of attachment to the IEEE 802 LAN required by those management entity or entities.
The information distributed via this protocol is stored by its recipients in a standard Management Information Base (MIB), making it possible for the information to be accessed by a Network Management System (NMS) using a management protocol such as the SNMP.
IEEE 802.1 AB can be utilized for many advanced features in a VoIP network environment. These features include basic configuration, network policy configuration, location identification (including for Emergency Call Service/E911), inventory management, and more. This Standard provides extensions to the IEEE 802.1AB base protocol to allow for these functions, and also provides behavioral requirements for devices implementing the extensions to enable correct multi-vendor interoperation.
LLDP-MED is based on the IEEE's 802.1AB LLDP and facilitates information sharing between endpoints and network infrastructure devices. Such data will simplify the deployment of endpoints, enable advanced device firmware management and boost support for E911 in enterprise networks. LLDP-capable devices periodically transmit information in messages called Type Length Value (TLV) fields to neighbor devices. This information includes chassis and port identification, system name, system capabilities, system description and other attributes. LLDP-MED builds upon these capabilities by adding media- and IP telephony-specific messages that can be exchanged between the network and endpoints. The new TLV messages will provide detailed information on Power over Ethernet, network policy, media endpoint location for Emergency Call Services and inventory.
Most of existing solutions are proprietary and consequently only work in a homogenous environment (i.e., where all devices are from the same manufacturer). The proprietary solutions include CDP, EDP, FDP and NDP.
However, there are also non-proprietary solutions that can work in a heterogeneous environment. This is the case of with LLDP and LLDP-MED, although they can only work in an IEEE 802 network. Also, neither LLDP nor LLDP-MED can discover interconnection nodes and multimedia nodes at once. LLDP is used to discover interconnection nodes while LLDP-MED is used to discover multimedia endpoint devices. Furthermore neither LLDP nor LLDP-MED can discover link properties such as delay, jitter or loss rate, although those characteristics are essential for the management of quality of service.
It should be emphasized that the terms “comprises” and “comprising”, when used in this specification, are taken to specify the presence of stated features, integers, steps or components; but the use of these terms does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.
In accordance with embodiments of the invention, an network topology discovery mechanism is provided at the scale of an administrative domain. Information about nodes and links, such as bandwidth, delay, jitter, name and description of devices are collected and stored in a database by way of a protocol. The protocol is notifications-based, where each device notifies its presence to its neighbor, for example, at a regular interval, and may be implemented on all nodes belonging to the administrative domain.
One aspect of the invention according to some embodiments involves way to discover network topology in a Next Generation Network (NGN) including an access network comprising a plurality of nodes for providing access to an Internet protocol (IP) core network. According to this aspect, each node of the plurality of nodes transmits information related to an identity (ID) of that node, and a corresponding lifetime value of the ID information, to each node of the plurality of nodes adjacent the transmitting node. Each of the plurality of nodes also receives and stores ID information and a corresponding lifetime value of the ID information of each respective node adjacent the receiving node.
Each node of the plurality of nodes receives a request for management information base (MIB) information from a network administration entity of the NGN. The MIB information includes an ID and lifetime value of the ID information of that node, and the stored ID information and a corresponding lifetime value of the ID information of each of the respective adjacent nodes. Each of the plurality of nodes transmits the requested MIB information to the network administration entity, which discovers and monitors the state and topology of the plurality of nodes. Each of the request destinations is based on the stored ID information and corresponding lifetime value that was received in response to a previous request.
Another aspect of the invention according to some embodiments provides a method for topology discovery of a plurality of network nodes connectable to one another by network links. The method is performed at each node and includes sending, to each adjacently linked node, information related to the ID of the node and an associated lifetime value of the sent information, receiving, from each adjacent linked node, information including an ID of the adjacent node and an associated lifetime value of the received information, and storing the received information in a MIB of the node. Each node monitors each stored lifetime value for a timeout, and for each timeout that occurs, it transmits to a management entity a notification message indicating loss of communication with the adjacently linked node associated with the corresponding lifetime value that timed out.
In yet another aspect of the invention, a system for topology and state discovery in a network including an access network and an IP core network comprises a plurality of node devices communicatively coupled to one another by a plurality of links, wherein one of the links is provided between any two of the node devices.
At least one edge node device is provided between a first group of the plurality of node devices and a second group of the plurality of node devices. The access network includes the first group of devices and the IP core network includes the second group of devices.
Provided in each node device in the first group is an information sharing subsystem for transmitting information related to an identity (ID) of that node and a corresponding lifetime value of the ID information to each node device of the first group adjacent the transmitting node device, and an information aggregation subsystem for receiving and storing at each node device of the first group ID information and a corresponding lifetime value of the ID information of each respective node device adjacent the receiving node device, and an information providing subsystem for transmitting, from a each node device of the first group, management information base (MIB) information of that node in response to a request from a network management entity, the MIB information including an ID and lifetime value of the ID information of that node, and the stored ID information and a corresponding lifetime value of the ID information of each of the respective adjacent nodes.
Additional aspects and advantages of the invention will be set forth in the description that follows, and in part will be apparent from the description, or may be learned from practice of the invention. The aspects and advantages of the invention will be realized and attained by the system and method particularly pointed out in the written description and claims hereof as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and exemplary only and are not restrictive of the invention, as claimed.
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention that together with the description serve to explain the principles of the invention. In the drawings:
a is a flow chart illustrating processes related to an exemplary discovery protocol operating in a initial mode in accordance with exemplary embodiments.
b is a flow chart illustrating processes related to an exemplary discovery protocol operating in an update mode in accordance with exemplary embodiments.
The various features of the invention will now be described with reference to the figures and in connection with a number of exemplary embodiments to facilitate an understanding of the invention. However, the aspects of the invention should not be construed as limited to these embodiments. Rather, these embodiments are provided so that the disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
Many aspects of the invention are described in terms of sequences of actions to be performed by elements of a computer system or other hardware capable of executing programmed instructions. It will be recognized that in each of the embodiments, the various actions could be performed by specialized circuits (e.g., discrete logic gates interconnected to perform a specialized function), by program instructions being executed by one or more processors, or by a combination of both. Moreover, the invention can additionally be considered to be embodied entirely within any form of computer readable carrier, such as solid-state memory, magnetic disk, and optical disk containing an appropriate set of computer instructions that would cause a processor to carry out the techniques described herein. A computer-readable medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, and a portable compact disc read-only memory (CD-ROM). Note that the computer-usable or computer-readable medium could even be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, via, for instance, optical scanning of the paper or other medium, then compiled, interpreted, or otherwise processed in a suitable manner, if necessary, and then stored in a computer memory. Thus, the various aspects of the invention may be embodied in many different forms, and all such forms are contemplated to be within the scope of the invention.
Current development of Next-Generation Networks (NGN) is moving toward architectures in which all services offered to a particular customer can access the same subscriber database. In particular, network operators are working on Fixed and Mobile Convergence (FMC), which enables to combination of wired and wireless/mobile networks to provide services to customers without dependency on location, access technology and device. Thus, a service provider can offer its customers a consistent set of personalized services, independent of the access media they use. For example, the IMS architecture was first specified by the Third Generation Partnership Project (3GPP/3GPP2), and is now being embraced by other standards bodies such as Telecommunication and Internet Converged Services and Protocols for Advanced Networking body of the European Telecommunications Standards Institute (ETSI/TISPAN). These architectures and services can be used across multiple access types, such as GSM, WCDMA, CDMA2000, xDSL, Ethernet and Wireless LAN.
A converged architecture will integrate heterogeneous access technologies as well as heterogeneous interconnection network elements and provide guaranteed or relative end-to-end QoS and reliability. This will require QoS management interaction with the access and core networks to obtain information about the capabilities and available resources of the network and decide whether the QoS requirements can be met. To meet this end or others described herein, an aspect of embodiments consistent with the invention includes an automatic network topology discovery mechanism at the scale of an administrative domain (i.e., the domain over which topology discovery is to be performed). Information about network nodes and links, such as device interface type, port identity, information lifetime, bandwidth, delay, jitter, name and description of devices is collected and stored in a database by way of a protocol described in detail later. The protocol is notifications-based (e.g., each device notifies its presence to its neighbor at a regular interval) and is implemented on all devices belonging to the administrative domain. The collected information is utilized to build a topology graph of the network nodes and links, which is a prerequisite to, among other things, admission control, QoS routing, fault detection (e.g., node or link failure) and root cause analysis, and inter-provider quality of service. The topology may be continually updated, and thus provide current automatically generated topological and state information of the administrative domain.
The transport layer 106 shown in
The CE 116 accesses the Access Network 110 and CN 120 under the control of the Admission Control and Resource Management Function (ACRMF) 140. The ACRMF 140 contains information relating to subscriber authentication, service authorization and location, makes generic policy decisions that are enforced in the Transport Layer, provides session control and management, and is responsible for setting up and taking down packet sessions.
Although the network shown in
Through various gateways, such as Border Node 122, the IP CN 120 may provide access to other networks, such as a packet data network (PDN) 130, (e.g., Intranet, Internet), other packet switched (PS) networks, and circuit-switched (CS) networks (e.g., PSTN/ISDN) (not shown). The CE 116 may have connectivity to one gateway border node for accessing a single PDN, or simultaneous connectivity with more than one gateway border node for accessing multiple PDNs. The gateway border node 122 may perform, among other functions, policy enforcement, packet filtering for each user, charging support, lawful interception, and packet screening. The border node 122 (e.g., a PDN GW) may provide an anchor for mobility between trusted/untrusted 3GPP and non-3GPP technologies such as WiMAX and 3GPP2 (CDMA 1X and EvDO).
The layer 2 protocol of the Access Network 110 terminates at the Edge Node 114, which translates the non-IP protocol of the Access Network 110 into the IP protocol of the IP CN 120. The information collected by the NTSDF 160 from the Access Network Edge Node 114 is used to discover layer 2 topology within the Access Network 110. The information about the Access Network 110 is obtained through the Edge Node 114 by way of a new discovery protocol operating at each node (e.g., switches) of the Access Network 110 and collected via the interface 136. In the Access Network 110, the ACRMF 140 interacts with policy enforcement points located in the Access Network 110, such as the Access Node 112 and IP Edge 114, via respective interfaces 142 and 144. The NTSDF 160 also collects information about the layer 3 topology (e.g., routers) of the IP Core network via interface 134 using protocols such as OSPF-TE or IS-IS-TE to discover the layer 3 topology of the IP CN 120.
The service layer 102 provides Services/Applications 150, such as telephony, instant messaging (IM), and presence services for both fixed and mobile users at the same time. It hosts application and content services, such as application servers, web servers etc., and may include or have access to a Home Subscriber Server (HSS) containing subscriber profiles and preferences. The Services/Applications 150 connects to users through the control layer.
By way of example,
The NASS 210 provides registration and initialization of the CE 230 to provide subscriber access to services in the service layer 102. The NASS 210 also provides network-level identification and authentication, manages the IP address space within the Access Network 240 (for example, dynamic provision of IP addresses), provides authentication to service sessions, access network configuration and location management.
The RACS 220 provides admission control and directs network traffic. Before admitting traffic to or from an individual user, the RACS 220 checks the user profile stored in the NASS 210, any operator specific policies, and resources availability (e.g., subscribed or available bandwidth). Included in the RACS 220 is an Access-Resource and Admission Control Function (A-RACF) 222, which manages access to resources and provides control of admission and the allowance of the resources. More particularly, the A-RACF 222 receives requests from the Service-based Policy Decision Function (SPDF) 224 and, based on available resources in its control, processes or rejects those requests. The SPDF 224 is a functional element that provides higher-level applications in the Service Layer with a single point of contact. The SPDF 224 coordinates the resource reservations requests that it receives from the Application Function (AF) 226 (the application-level controller, such as a SIP server).
As shown in
The Core Border Node 252 includes a Border Gateway function (BGF) 254 that provides interfaces between two IP transport domains, although a BGF may be located at the border of other networks, such as a home network of a user or an access network. The BGF 254 may select a path across the Regional Core Network 250 to an egress node bordering the terminating sub-network at or near the end point, and may provide services such as Network Address Translation (NAT), gates opening/closing (gates filter a message according to the IP address/port), packet marking of outgoing stream, resource allocation and bandwidth reservation of upstream/downstream allocation and conversion of IP addresses and ports, policing the incoming stream, IP address allocation and anti-spoofing, usage metering, Deep Packet Inspection (DPI), interconnect between Internet Protocol version 4 (IPv4) networks and Internet Protocol version 6 (IPv6) networks, lawful interception and hiding topology.
The Transport Layer 200 shown in
The NTSDF 260 defines a new function in the RACS 220, which includes the services of collecting and storing network topology and state information, managing, filtering and formatting the stored information depending on the desired output, providing decision information to the admission control function, providing a path or a set of paths to the routing function, and interfacing with NTSDFs of neighborhood domains.
As shown in
The lower Topology layer 310 of the NTSDF 360 has specialized modules that perform multiple tasks related to topology and state discovery. It includes a Node Discovery Module 312, a Data Transformer Module 314 that receives information from the Node Discovery Module 312, and a Topology and State Database 316 that receives information output from the Data Transformer Module 314.
During topology discovery of an access network, for example, the Access Network 240 of
The time-to-live information includes a lifetime value (e.g., a number of seconds) indicating a period of time that the identity information is valid (e.g., how long the receiving device should maintain the received information). This time-to-live information associated with the remote (i.e., neighboring) node information provides the local node with a way to determine a timeout period for the information. For example, when a time period equal to the lifetime value elapses (e.g., because the local node does not receive a TLV before the information lifetime expires), the local node may remove the information related to the remote node from its remote MIB and notify the NTSDF 360 so that the topology and state of the network can be updated.
The information collected from the MIBs of node devices is passed to a Data Transformer Module 314, which prepares it for insertion into the Topology and State Database 316. Preparation by the Data Transformer Module 314 may include interpreting and transforming node and link properties extracted from the MIBs into a format and language corresponding to that of the Topology and State Database 316. For example, this module may interpret value 5 of the field Device Type of the TLV capabilities as an “IP telephone.” The Data Transformer Module 314 also performs calculations of QoS parameters of links based on information collected by the Node Discovery Module 312. The transformed data is inserted into the Topology and State Database 316.
In some embodiments, the technology utilized by a node may not implement LLDP, be aware of LLDP type messages (e.g., a CE node using ATM DSL technology), or otherwise cannot operate using the protocol described above for collecting MIB information. However, topology discovery of such nodes in a heterogeneous network may still occur. Referring again to
The Topology and State Database 316 stores and manages the transformed information collected from the network nodes. It is the repository where modules of the Topological and QoS Services layer 320 find the information needed to perform their calculation or make their decisions. The Topology and State Database 316 contains the information from which the Network Topology and State Discovery Function 360 builds a topology graph (G) including vertices (V) and edges (E), which respectively represent links and nodes of the network.
In some embodiments, a NTSDF may operate in a plurality of modes as illustrated by the NTSDF 500 shown in
With reference to
Next, the information extracted from MIBs in process 512 may be filtered in process 513 to keep only information of interest. For example, Table 2 contains an exemplary list of information that may be retained:
The filtered MIB information may be processed in by an interfaces grouping process 514, which addresses the possibility that a node may have multiple interfaces, each having its own MAC address. The information related to an interface corresponds to one entry in the MIB. When the information contained in the MIB is extracted, it should be associated to only one node.
A link deduction process 515, which may be performed in parallel with the interfaces grouping process 514, determines links between the nodes based on the information extracted from the MIBs and interface grouping. A link exists between two interfaces if the ID of the one is presented in the remote MIB of the other and vice versa. Processes 512-514 generate a list of nodes and links along with their corresponding properties at 516.
A check is performed in process 518 to determine whether all nodes in the queue have been visited. If not, processes 512-516 are repeated for each MAC address not yet visited. In this way, the Node Discovery Module 312, using the MIB information of the local node and remote MIB information of adjacent nodes, hops from node-to-node to eventually discover the initial topology and state of the network.
If the check performed in process 518 determines that all nodes have been visited, the list of nodes and links and their properties aggregated in the Node Discovery Module 312 may be further processed in the Data Transformer Module 314 before the collected information is entered in the Topology and State Database 316. More particularly, the collected data may be interpreted in process 522, QoS parameters may be computed in process 524, and the resulting data may be formatted in process 526.
The data interpretation process 522 interprets some node and link properties that are in numerical form, which may not be meaningful from a management perspective. Such properties may be given a semantic expression, for example, to help a network administrator more easily understand and use them. For example, if the value of the field <system capabilities> were 4, then the device would be interpreted as a router.
The computation of QoS parameters process 524 computes QoS parameters such as link delay, packet lost rate and jitter based on the information extracted from MIBs.
The data formatting process 526 of the Data Transformer Module 314 puts the nodes, links and their properties in the format that corresponds to the destination database. For example, the data may be put in the form of a relational, hierarchical or network database.
The details of the Topological and QoS Services layer 320 are now described with reference to
The Network Management module 328 manages the topology and state discovery, for example, start, stop, view, filter, print, export, etc. The Network Management module 328 also configures topology discovery protocol parameters, such as Send/Receive Mode, notification interval time, and other parameters.
The Admission Control module 322 of the Topological and QoS services layer 320 receives admission control requests from the A-RACF, checks the state of resources in the topology and state database, and responds to the admission control requests. If a response to an admission control request is positive, the Admission Control module 322 updates the database (e.g., to reflect a change in resource utilization). The Admission Control module 322 also may send requests to the admission control modules of the adjacent NTSDFs and receives requests from the admission control modules of the adjacent NTSDFs.
The QoS Routing module 324 receives QoS path requests from the AF or from the routing modules of the adjacent NTSDFs, computes a QoS path that satisfies the received path request, transmits the computed path to the requester, and sends requests to the routing modules of the adjacent NTSDFs.
The Inter-Provider QoS module 326 exposes classes of services to adjacent NTSDFs, and explores and selects classes of services of adjacent NTSDFs that satisfy the flow constraints.
In the update mode of the NTSDF 500 shown in
In some embodiments, the send notification process 506 optionally sends one of two types of notification messages. In a first option, the Network Node 502 sends a first type of notification message at 506 that simply indicates something has changed in the remote MIB of the Network Node 502. Upon receiving this notification, the Network Management module 328 of the NTSDF 500 pulls the remote MIB of the Network Node 502 and performs discovery process, as illustrated by the path “without remote MIB” from the “Notification Type?” decision block 508. The NTSDF 500 operating in this way may process each update in the order they are received by extracting the MIB at 512, filtering the extracted MIB at process 513, and deducting any link changes and interface grouping in processes 514 and 515 as described above. However, because the processes of listing nodes and properties, and hopping to other nodes in the network would not be necessary when updating a previously determined topology configuration, processes 516 and 518 of
In another option according to some embodiments, the Network Node 502 may send a second type of notification message at 506 that contains the remote MIB of that node. After receiving this message, the Network Management module 328 of the NTSDF 500 performs the discovery process as described above for the first type of message, but the process related to extracting the MIB from the node is not performed, as illustrated by path “with remote MIB” from the decision block 508, because the MIB has already been sent in the notification message.
The protocol for building and updating a topological graph is notifications based and may be implemented on all devices belonging to an administrative domain.
For example,
Each of the IP edge router 610, and switches 620, 622 and 624 exchanges MIB information bi-directionally with their neighboring nodes (i.e., switches) using protocol as described herein. At the lowest level of the network 600, each of the devices 626a-626c may unicast their MIB information to the switch 622, and the switch 624 may receives MIB information unicast from device 626d. Thus, each node stores both its own local MIB information and remote MIB information from any adjacent node.
During discovery, for example, an initial or restart discovery mode of the NTSDF 660, MIB information is first collected about the network 600 at the IP Edge router 610 (e.g., using SNMP). The MIB information includes the local MIB information of the IP Edge router 610 as well as remote MIB information related to switch 620 and switch 622 (e.g., identity and time-to-live information). Using this information, the NTSDF 660 determines that switches 620 and 622 must be visited and places their addresses into a queue for extraction of their MIB information. While the extracted MIB information of switch 620 may not include information regarding additional adjacent nodes other than switch 622 and the IP Edge 610, its local MIB provides other useful information, such as information from which QoS parameters may be computed. When the NTSDF extracts MIB information from Switch 622, it learns of the adjacent switch at node 624 and places it in the queue for extraction. These processes continue until all the nodes are identified and their respective node and link properties are stored in the database of the NTSDF 660.
After initial discovery, the NTSDF 660 may enter an update mode in which only changes to the initial topology are detected and processed to update the topology and state information of the network 600. For example, if the link 623 were to go down, switch 622 would cease to receive TLVs from the switch 624. After time-to-live of switch 624's information stored in switch 622 expires, switch 622 may send a notification message (or its MIB information) to the NTSDF 660, which causes the NTSDF 660 to update the topology and state database. Similarly, an existing node will notice a node and link added to the network 600 after receiving its MIB information.
In some embodiments, the Link information table 720 stored in the NTSD module 700 may include, for each link, Link ID as the primary key; information relating to Link Type, which identifies whether a link is a point-to point link, a link to transit network, a link to a stub network, or a virtual link. Source Node ID information for identifying a Node ID of the sending device, Destination Node ID for identifying the Node ID of the receiving device, and Medium, which describes the media used for the signal transmission (e.g. coaxial cable, optical fiber, etc.). Link information 720 also may include Max Bandwidth, which is stored information relating to the maximum bandwidth of the link; Reservable Bandwidth that defines a maximum bandwidth that can be reserved for QoS traffic; Remaining Bandwidth defining maximum bandwidth minus reserved bandwidth, and Reserved Bandwidth, which is the part of the Reservable Bandwidth that is effectively reserved. The Administrative Group is the group the link belongs to for business or administrative purpose, and Status indicates if the link is active or inactive, and Mode indicates whether the link is simplex or duplex.
A node is located at either end of the each link in the network. The Node information table 740 in
The QoS Parameter information table 760 of the logical module 700 contains quality of service capabilities information for links stored in the Link information table 720. The primary key in the QoS Parameter table 760 is Parameter, which expresses the QoS capabilities of a link in terms of QoS parameters such as delay, jitter, loss rate etc. Also stored in the table may be the field Link ID as a foreign key to the Parameter primary key, and the Value field, which may represent a delay value for a link, if delay is assigned to that link as a QoS Parameter.
The interface information table 780 of the NTSD module 700 is related to the node information table 740 and describes interface properties of devices at the network nodes. With reference to
As described above, the Topology and State Database 316 may have the logical model 700 and is included with the NTSDF 360 connected to the A-RACF 222. The X2 interface may be utilized to collect topological information of the network and to forward them to the NTSDF. When a new request of admission is received from the SPDF 224, the A-RACF 222 interrogates the NTSDF to obtain information on the state of the resources of the network.
Admission control is generally associated with each interconnection node in a network. In fact, to establish a flow path through a network, all interconnection nodes that belong to the path must accept the flow. With an NTSDF, admission control can be done on a single node. The node will have up-to-date information about network resources and their level of use. This will speed up the admission process.
When multiple routers perform admission control, the routers must maintain flow states. This requirement has led to the scalability problem of IntServ. However, by managing flow states on a single node (dimensioned adequately), routers are freed from maintaining flow states. Consequently, router computing power and storage capacity may be reduced because maintaining flow states is no longer necessary.
QoS routing is about selecting the best path that satisfies QoS constraints of a flow. Those QoS constraints include bandwidth, delay, jitter, lost rate, etc. The number and the nature of constraints directly influence the complexity and the cost of computing the best path. With an NTSDF, the best path may be computed during the admission process. This avoids new computations and signalization in the network with respect to route flow's packets.
The knowledge of the true physical topology of a network is capital for many administrative tasks such as proactive and reactive resource management, event correlation, and root cause analysis. With an NTSDF, a network administrator can automatically perform a complete inventory of network devices, identify inactive connections, detect intruder, and proactively analyze the impact of a node or link failure in order to improve the network survivability.
In order to provide end-to-end QoS, providers must have agreements on classes of service and their respective performance. This approach is partially due to the fact that each provider defines and treats its classes of services in its own ways. To this end, an NTSDF may be used to dynamically negotiate the desired class of service. In fact, each provider may publish its classes of services with their performances so that other provider can dynamically choose the class which best matches their requirements for a particular flow.
The invention has been described with reference to particular embodiments. However, it will be apparent to those skilled in the art that various changes and modifications can be made in the present invention without departing from the spirit and scope thereof Thus, it is intended that the present invention cover the modifications of this invention provided they come within the scope of the appended claims and their equivalents.
