GPRS tunneling protocol path integrity

BACKGROUND OF THE INVENTION

This disclosure is directed towards systems and methods for accumulating and maintaining information regarding states of nodes in telecommunication networks. The accumulated information can be made available to call processing and other portions of the network. Providing the accumulated information allows for increased efficiency in call processing and other network activities. Embodiments will be described with reference to 3^rd Generation Partnership Project (3GPP) Universal Mobile Telecommunications System/General Packet Radio Service (UMTS/GPRS) networks. However, embodiments may be adapted for use in other network environments.

The 3^rd Generation Partnership Project is a collaboration agreement between a number of telecommunications standards organizations. The 3GPP develops and promulgates technical specifications and technical reports that guide equipment manufacturers and communications service providers in the development and implementation of communications networks. More information regarding 3GPP can be found at <u>http://www.3gpp.org</u>. The postal address for the 3GPP is 650 Route des Lucioles, Sophia Antipolis, Valbonne, France.

Referring to FIG.1, an exemplary network portion <b>110</b> addressed by standards distributed by the 3GPP includes a mobile device <b>114,</b> a node B or cell site <b>118,</b> a Radio Node Controller (RNC) <b>122,</b> a first Serving GPRS Support Node (SGSN) <b>124,</b> a first Gateway GPRS Support Node (GGSN) <b>128,</b> a Charging Gateway Function (CGF) <b>132,</b> a second SGSN <b>136</b> and a second GGSN <b>142.</b>

For example, the mobile device is a cell phone, laptop computer, personal digital assistant or other device adapted to interface with a mobile communications network. The Node B <b>118</b> is a base station or a network radio. The Node B <b>118</b> is a major component of a cell site and acts as a link between the mobile device <b>114</b> and the rest of the network <b>(122, 124, 128, 136, 142).</b>

The RNC <b>122</b> controls and coordinates the operation of the Node B <b>118</b> and the plurality of other Node Bs (not shown). For example, the RNC <b>122</b> coordinates a handoff between the plurality of other Node Bs and the Node B <b>118</b> of the network portion <b>110</b> as the mobile device <b>114</b> moves out of range of the other Node Bs and into the range of the Node B <b>118</b> of the network portion <b>110.</b> Additionally, the RNC <b>122</b> acts as a link between the Node B 118 (and the other Node Bs) and the rest of the network (e.g., <b>124, 128, 136, 142).</b>

The first SGSN <b>124</b> acts as a gateway between the RNC <b>122</b> and the rest of the network (e.g., <b>128, 136).</b> For example, the first SGSN <b>124</b> acts as a switching element, directing message traffic to and from the RNC, from and to other points in the network (e.g., <b>128, 136, 142).</b> The first GGSN <b>128</b> acts as a gateway between the exemplary network portion <b>110</b> and another network. For example, the first GGSN <b>128</b> acts as a gateway between the exemplary network <b>110</b> and a public data network <b>146.</b>

The first SGSN <b>124</b> might also direct message traffic to and from the RNC <b>122</b> from and to the second SGSN <b>136.</b> For instance, the second SGSN acts as an interface to other Radio Node Controllers (not shown) and therefore, to other Node Bs. If the called party is associated with another mobile network, the first SGSN <b>124</b> might pass message traffic between the RNC <b>122</b> and the second GGSN <b>142</b> because the second GGSN <b>142</b> acts as a gateway or interface between the exemplary network <b>110</b> and other public land mobile networks <b>150.</b>

The Charging Gateway Function <b>132</b> is an accounting device. The CGF <b>132</b> receives charging data records (CDRs) for the purpose of billing or debiting accounts of subscribers (e.g., the user of the mobile device 114).

As is outlined, for example, in 3GPP Technical Specification Publication TS 29.060, control functions in networks such as the exemplary network <b>110</b> are achieved through the exchange of GTP-C or control plane messages between for example, SGSN (e.g., <b>124, 136)</b> and GGSN (e.g., <b>128, 142).</b> However, at the lu-ps interface between RNCs and SGSNs, the control plane is based on Asynchronous Transfer Mode (ATM) technology that is used to transport the Radio Access Network Application Part (RANAP) messages via broadband SS7 standards, while GTP-U provides the user plane. This means that an entire PDP (Packet Data Protocol) context can be established even when a user path associated with the PDP context is disabled. Similar issues can arise between SGSN and GGSN nodes because GTP-C and GTP-U paths can be different. For example, GPT port numbers may be different. In effect, the current standards call for setting up PDP context under the assumption that a selected path is currently available. When the assumption proves to be incorrect, system overhead is adversely effected. Messages are resent until a number of retries have failed. Additionally, load sharing algorithms attempt to channel message traffic to unloaded paths unaware that the reason the paths are unloaded is because they are disabled or administratively locked. Therefore, network resources can be wasted performing repeated retries and calls can be delayed and/or dropped.

For at least the foregoing reasons, there is a desire for systems and methods that increase network status awareness for the nodes that select paths or routes when setting up calls or paths for network message traffic.

SUMMARY OF THE INVENTION

A method for providing improved GTP path integrity assurance in a UMTS/GPRS network includes receiving GTP messages, building a path integrity table of records from information included in the GTP messages and making information in the path integrity table available to call processing and OAM subsystems of the GPRS network. For example, each record in the path integrity table includes a path definition, an operational state entry and a time stamp entry. The path definition includes at least a source IP address, a destination IP address and a port number. The operational state entry can have a value selected from - Enabled-, -Disabled- and --Unknown-. The time stamp entry has a value indicative of a time information in the record was last updated. The method can also include updating records in the path integrity table when additional GTP messages associated with path definitions having records in the table are received. The records are updated based on information included in the additional messages. When expected messages are not received, the records are updated based on the lack of reception of the expected messages.

Receiving GTP messages can include receiving GTP-U and/or GTP-C messages. For example, Receiving GTP Messages can include receiving Create PDP Context Request messages, GTP Echo Request messages, GTP Echo Response messages, Create PDP Context Response messages and GTP User datagrams. Additionally receiving GTP messages can include receiving a new kind of message referred to herein as a Gratuitous GTP Echo Response message which can be transmitted by a node when resources of the node undergo an administrative state change.

The method can include receiving administrative state information regarding the path and storing the administrative state information in an administrative state entry in the path integrity protocol table in association with the path definition. As mentioned above, in some embodiments, when this occurs the method includes transmitting a Gratuitous GTP Echo Response message indicating the value of the administrative state entry to inform another node of the new administrative state. For example, administrative state information can be inferred by a receiving node from a comparison of the Restart Counter within the Recovery Information Element within the Gratuitous GTP Echo Response message and a Restart Counter value stored in a table in the local or receiving node.

Updating records in the path integrity table can include comparing values of the time stamp entries of records in the table to a current time to determine ages of the records, transmitting a GTP Echo Request to the destination IP address and port number associated with any record having an age greater than a desired record age limit, the GTP Echo Request including the source IP address associated with the record and updating the entries of the any record based on a received GTP Echo Response associated with the GTP Echo Request or on a lack there of.

For example updating the entries of the a record can include receiving the GTP Echo Response message and updating the operational state entry to --Enabled-- and the time stamp entry to a time associated with the GTP Echo Response message. If it is determined that the GTP Echo Response message was not received, the method can include comparing a retry counter value to a retry limit, transmitting another GTP Echo Request message if the retry counter value is less that the retry limit, incrementing the retry counter; and updating the operational state entry to --Unknown--. If it is determined that the GTP Echo Response message was not received, the method can include comparing a retry counter value to a retry limit, updating the operational state entry to --Disabled- if the retry counter value is equal to or greater than the retry limit and updating the time stamp entry to a time associated with the updating of the operational state entry to -Disabled--.

In some embodiments, when the operational state entry is set to disabled, the method includes setting a path disabled time stamp entry associated with the path definition in the path integrity table to a time associated with the updating of the operational state entry to --Disabled--. Those embodiments can also include comparing the value of the path disabled time stamp entry to a current time, thereby determining a path disabled duration and deleting the record associated with the path definition from the path integrity table if the path disabled duration is greater than a predefined path disabled time limit.

Building the path integrity table can further include manually entering a record including a manually entered path definition, the manually entered path definition including at least a source IP address, a destination IP address and a port number.

In an exemplary embodiment, a method for providing improved GTP path integrity assurance in a UMTS/GPRS network includes defining a path based on a first node IP address, a second node IP address and a UDP port number receiving, at a first node, a first GTP message from a second node extracting the first node IP address from the first GTP message, extracting the second node IP address from the first GTP message, determining an operational state of the path based on the first received message and storing the operational state of the path in a path integrity table, in association with the path definition and a time stamp related to a time the first GTP message was received.

Defining the path can include defining a static path based on a static first node IP address, a static second node IP address and a static UDP port number and storing the static path definition as a path entry in the path integrity table. Alternatively or additionally, defining the path can include defining a dynamic path based on a dynamic first node IP address, a dynamic second node IP address and a UDP port number. Defining the path can include defining the path based a uniform or standard UDP port number.

The method of can include determining a difference between a value of the time stamp and a current time and transmitting a GTP Echo Request message from the first node to the second node, using the UDP port number and using the first node IP address as a source address and the second node IP address as a destination address, if the difference between the value of the time stamp and the current time is greater than a predetermined refresh time.

For example, where the local node is a Radio Node Controller the method can include transmitting a GTP Echo Request from a Radio Node Controller.

Receiving the first GTP message from the second node can include, for example, receiving a Create PDP Context Request, a GTP Echo Request message, a Create PDP Context Response message, a GTP User datagram, a Gratuitous GTP Echo Response message, as mentioned above, or other GTP messages.

The method can also include receiving, at the first node, a second GTP message from the second node, extracting the first node IP address from the second GTP message, extracting the second node IP address from the second GTP message, extracting the UDP port number from the second GTP message, determining the path definition based on the first node IP address, the second node IP address and the UDP port number; determining an operational state of the path based on the second received message, updating the operational state entry associated with the path definition in the path integrity table and updating the time stamp with a value related to a time the second GTP message was received.

Where it is determined that the second node has not responded to the transmitted GTP Echo Request message the method can include determining an operational state of the path to be --Disabled- based on the determination that the second node has not responded to the transmitted GTP Echo Request message, updating the operational state entry associated with the path definition in the path integrity table to be --Disabled-- and updating the time stamp with a value related to the determination that the second node has not responded to the transmitted GTP Echo Request message. Under these circumstances, the method can also include setting a Path Disabled Time Stamp entry to a value related to the determination that the second node has not responded to the transmitted GTP Echo Request message. The method can also include deleting the path definition and associated information from the path integrity table if the path disabled duration is greater than a predefined path disabled duration limit.

If it is determined that a GTP Echo Response was not received, the method can include updating the operational state of the path to be - Unknown-- and transmitting a second GTP Echo Request message from the first node to the second node, using the port number and using the first node IP address as a source address and the second node IP address as a destination address.

In some embodiments, the method includes extracting a Restart Counter value from the first GTP message and storing the Restart Counter value, in association with the path definition in the path integrity table.

Some embodiments include storing an administrative state of the path, in association with the path definition in the path integrity table.

In some embodiments, the method includes receiving administrative state information regarding the path and storing the administrative state information in an administrative state entry in the path integrity protocol table in association with the path definition. In some of these embodiments, the method includes transmitting a Gratuitous GTP Echo Response message.

Preferably the information in the path integrity protocol table is used to improve network efficiency. For example, the method can include consulting the path integrity table to determine the operational state of the path before attempting to set up a GTP tunnel on the path and choosing an alternate route for the GTP tunnel if the path integrity table indicates the path is disabled or unknown.

One embodiment of a node operative to carry out the path integrity method is a UMTS/GPRS network node comprising main network node functional blocks, a GTP Echo Request/Response processor that is operative to transmit GTP Echo Requests to other nodes in a UMTS/GPRS network when directed to do so by other components of the UMTS/GPRS network node and receive and process GTP Echo response messages from the other nodes in the UMTS/GPRS network as directed by the other components of the UMTS/GPRS network node and a path integrity protocol module that is operative to build a path integrity protocol table by extracting path integrity information from network message traffic associated with the node and record the extracted information in the path integrity protocol table, update the information recorded in the table by extracting updated path integrity information from additional network message traffic associated with the node and recording the extracted updated information in the table, monitor the age of recorded information stored in the table and update old information in the table by directing the GTP Echo Request/Response processor to transmit GTP Echo Requests over paths associated with the old table information and to provide information to the path integrity protocol module regarding the reception or lack of reception of GTP Echo Response messages associated with the GTP Echo Requests, the path integrity protocol module being further operative to replace the old recorded information with new information based on the information provided to the path integrity protocol module by the GTP Echo Request/Response processor.

The main network node functional blocks can be Radio Node Controller main functional blocks, Serving GPRS Support Node main functional blocks, and/or Gateway GPRS Support Node main functional blocks.

The path integrity protocol module can be operative to build a path integrity protocol table by extracting path integrity information from Create PDP Context Request message traffic, GTP Echo Request message traffic, GTP Echo Response message traffic, Create PDP Context Response message traffic, GTP User datagram message traffic or other GTP message traffic.

The path integrity protocol module can be further operative to build a path integrity protocol table by extracting path definition and path operational status information from the network message traffic associated with the node and record the extracted information in the path integrity protocol table. For example the path definition information can include a source IP address, a destination IP address and a port number extracted from the network message traffic associated with the node.

The path integrity protocol module can be further operative to build a path integrity protocol table by extracting Restart Counter information from the network message traffic and storing the Restart Counter information in association with the extracted path definition information.

In some embodiments the path integrity protocol module is further operative to delete path information from the path integrity table when an operational status of the path associated with the path information has been --Disabled-- for longer than a path disabled duration limit.

In some embodiments, the path integrity protocol module is further operative to accept manual path definition entries and include records associated with the manual path definition entries in the path integrity protocol table.

In some embodiments the path integrity protocol module is further operative accept manually entered administrative state information associated with a path definition record, and update an administrative state entry in the path integrity protocol table associated with the path definition record according to the manually entered administrative state information. In some of those embodiments the path integrity protocol module is further operative to transmit a Gratuitous GTP Echo Response message indicating the value of the administrative state entry.

DESCRIPTION OF THE DRAWINGS

The invention may take form in various components and arrangements of components, and/or in various procedures and arrangements of procedures. The drawings are only for purposes of illustrating preferred embodiments. They are not to scale, and are not to be construed as limiting the invention. <ul id="ul0001" list-style="none" compact="compact"><li>Fig. 1 is a block diagram of a portion of a prior art network.</li><li>Fig. 2 is a diagram of an exemplary path integrity protocol table.</li><li>Fig. 3 is a flow chart outlining a method for building and maintaining a path integrity protocol table.</li><li>Fig. 4 is a flow chart outlining an embodiment of the method of Fig.3.</li><li>Fig. 5 is flow chart outlining a method for receiving path status information.</li><li>Fig. 6 is a flow chart outlining a method further to the method of Fig. 3 for maintaining a path integrity protocol table.</li><li>Fig. 7 is a block diagram of a portion of a network operative to build and maintain a path integrity protocol table according to the method of Fig. 3 and Fig. 6.</li></ul>

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Currently, some UMTS/GPRS network nodes (those including the functionality of a GTP Echo Request/Response Processor (e.g., <b>154</b>)) can determine the status of a path along which a PDP context is already established by transmitting GTP Echo Request messages and receiving and processing GTP Echo Response messages. However, the nodes are unaware of and cannot transmit GTP Echo Requests over paths that are not currently associated with active PDP contexts. Furthermore, some nodes, such as, Radio Node Controllers (RNC) (e.g., <b>122)</b> are historically not equipped to transmit GTP echo requests. Even those nodes that are equipped to request and receive path status information are not equipped to store the status information for any length of time. Instead, the nodes transmit new GTP Echo Requests along paths associated with established PDP contexts whenever the purposes of the nodes require it. Therefore, the nodes (e.g., <b>122, 124, 128, 136, 142</b>) are completely unaware of the status of paths along which PDP context are not currently established and only some nodes are able to determine the status of paths along which PDP context are established. As explained above, this can lead to wasted resources, reduced quality of service, and dropped calls, for example, in the case of network or network node failures.

Referring to FIG. 2, call processing and/or Operations, Administrations and Maintenance (OAM) processes can be made more efficient where network nodes have ready access to network status or path integrity information. This information can be collected and stored according to a Path Integrity Protocol. The Path Integrity Protocol calls for the establishment of a Path Integrity Protocol Table <b>210</b> at each network node having call processing and/or OAM functions (e.g., RNC, SGSN, GGSN). Each entry <b>214</b> in the Path Integrity Protocol (PIP) table includes a path definition <b>218</b> and other information <b>222</b> associated with the path definition <b>218.</b> Each path definition <b>218</b> includes a first or Local Node IP address <b>226,</b> a second or Remote Node IP address <b>230</b> and a UDP port number <b>234</b> or GTP version number. The information <b>222</b> associated with the path definitions <b>218</b> can include, for example, a Path Type <b>238</b>, an Administrative State <b>242</b>, an Operational State <b>246</b>, a Time Stamp <b>250</b>, a Path Disable Time <b>254</b> and a Remote Node Restart Counter <b>258</b>.

A unique GTP path is a GTP User datagram Protocol/Internet Protocol (UDP/IP) connectionless, unidirectional or bidirectional path between two end points. An IP address and a UDP port number define a GTP endpoint. An associated pair of GTP endpoints defines a GTP path.

The Local Node IP address <b>226</b> is an IP address associated with the node building and maintaining the particular PIP Table (e.g., <b>210</b>) in question. The Remote Node IP address <b>230</b> is an IP address associated with another network device with which the local node communicates. For example, if the local node is an SGSN, then the PIP table <b>210</b> may include remote node address entries <b>230</b> associated with RNCs, GGSNs and other SGSNs.

UDP port numbers are directly associated with GTP versions and both end points of a path use the same version of GTP. Therefore, only one UDP port entry <b>234</b> is required to define <b>218</b> a path. However, extended or different path definitions are anticipated. If protocols evolve or are developed that use different port numbers at a local node than are used at a remote node than the PIP Table can be extended to include local and remote UDP port numbers or GTP versions.

Path Type <b>238</b> entries are optional. Where a Path Type entry <b>238</b> is included in the PIP Table (e.g., <b>212</b>), the Path Type entry <b>238</b> can have a value of --Static-- or --Dynamic--. A static path is one for which resources are permanently assigned or at least assigned for an extended period of time. Dynamic paths are established over resources that can be automatically reallocated to a different path when network message traffic levels change.

The Administrative State entries <b>242</b> are also optional. Where included, Administrative State <b>242</b> entries can have values --Locked-- or --Unlocked--. Administrative State entries <b>242</b> are set manually. For example, when craft personal take a resource offline for maintenance or repair, they make configuration entries or adjustments so informing the node. Those entries or configurations provide the necessary information for populating the Administrative State entries <b>242</b> of the PIP Table <b>210.</b>

In some embodiments, the Administrative State entry <b>242</b> is related only to the local node. In other embodiments, the local node may be informed of the Administrative State of the remote node and so the Administrative State entry <b>242</b> can be related to the path as a whole. For example, as will be described in greater detail below, a Gratuitous GTP Echo Response message including an updated Restart Counter value can be transmitted by a remote node when craft personnel place the remote node in an administrative -Locked-- state. Alternatively, the PIP Table can be expanded to include an Administrative State entry for each of the local node and the remote nodes.

The values of the Operational State entries <b>246</b> are determined by the local node. For example, the operational state of a path is determined, derived or inferred from the reception or lack of reception of GTP messages over the path. As will be explained in greater detail below, the values of the Operational State entries <b>246</b> can be -Enabled--, --Disabled-- and --Unknown-.

More information regarding administrative state and operational state parameters can be found in Recommendation X.731 of the International Telegraph and Telephone Consultative Committee (CCITT) of the International Telecommunication Union (ITU).

Each entry <b>214</b> in the PIP Table <b>210</b> includes a Time Stamp <b>250</b> entry that indicates the freshness of the data <b>222</b> associated with the path definition <b>218</b>. Each time the path integrity data associated with a path entry <b>214</b> is updated, the time stamp entry <b>250</b> is revised to reflect the current time or if table updating is delayed, a time associated with the path integrity determinations.

The Path Disabled Time entry <b>254</b> is a second time stamp. The Path Disabled Time entry <b>254</b> is only valid for records <b>214</b> or path definitions <b>218</b> that are associated with an Operational State entry <b>246</b> having a value of -Disabled-. The Path Disabled Time <b>254</b> indicates the time when it was first determined that a path <b>218</b> was disabled. Additionally, or altematively, in some embodiments, the Path Disabled Time may be associated with and valid for paths having an Administrative State value of --Locked-. The Path Disabled Time entries <b>254</b> are used to prevent the PIP Table <b>210</b> from growing too large and from containing too many invalid or dead entries. As will be described in greater detail below, when the Path Disabled Time entry <b>254</b> indicates that a path entry <b>214</b> associated with a dynamic path has indicated that the dynamic path has been disabled or locked for an extended period of time, the dynamic path entry <b>214</b> is removed or flushed from the PIP Table <b>210</b>. By definition, static paths are not automatically flushed from the PIP Table <b>210.</b> Instead, they can be manually removed from the table <b>210</b> when the associated resources are reallocated or removed from service.

The Remote Node Restart Counter entries <b>258</b> are optional. As will be explained in greater detail below, the Remote Node Restart Counter for a given path can be determined from GTP messages received over the path. If a GTP message indicates that the restart count of a remote node is different than the count value of the Remote Node Restart Counter entry <b>258</b> for that path, then the remote node has restarted recently and PDP contexts associated with the path may need to be tom down and/or reestablished.

Referring to FIG. 3, a method <b>310</b> for building and/or maintaining a PIP Table (e.g., <b>210</b>) includes defining <b>314</b> a path, receiving <b>318</b> path status information and determining <b>322</b> if an entry (e.g., <b>214)</b> already exists for the defined path. If an entry already exists, then the method <b>310</b> includes updating <b>326</b> the record or entry (e.g., <b>214</b>) for the defined path based on the received <b>318</b> information. If <b>322,</b> the path is not already included in the PIP Table, the method <b>310</b> includes adding <b>330</b> a record or entry (e.g., <b>214</b>) for the path.

A path may be defined <b>314</b> by craft personnel at system commissioning or provisioning. For instance, craft personnel may define a static path in order to accommodate a minimum level of anticipated message traffic between two end points. Additionally, or alternatively, craft personnel may predefine (and preload) dynamic paths. Alternatively, paths are defined dynamically by call processing and/or administrative system components. Therefore, information about path status can be received <b>318</b> at a node from manual craft personnel entry. Additionally, path status information can be received <b>318</b> as part of a normal network message traffic handling. For instance, GTP messages include path definitions as part of their routing information. At least some GTP messages (e.g., GTP Echo Response, Create PDP Context Request) carry remote device recovery information including, for example, remote device Restart Counter values. The fact that a GTP message is received from a remote device along a defined path indicates that the Administrative State entry <b>242</b> of the path associate with the remote device should be set to -Unlocked- and that the Operational State entry <b>246</b> of the path should be set to -Enabled-.

While path status or state information is described here as being stored in a table for purposes of ease of explanation, the status information is actually stored in some electronic form. For example, the PIP Table <b>210</b> information can be stored in a database. The status or state information <b>222</b> is stored in the database in association with the appropriate path definition <b>218</b> or path entry <b>214.</b> Path definitions <b>218</b> can be used as, or used to generate, unique keys into the database. Determining <b>322,</b> if a path is already included in a PIP Table can include using the received <b>318</b> path information to generate a key into the database. If a query based on the key returns results, then the path is already included in the PIP Table and the state information <b>222</b> can be updated <b>326</b> based on the received <b>318</b> path status information. If <b>322</b> the results of the database query based on the received <b>318</b> path definition indicates that a record associated with the path does not exist, then a new record is added <b>330</b> including or associated with the received path definition <b>318</b> and state information <b>222.</b>

For instance, in UMTS/GPRS networks, an embodiment of the method <b>310</b> for building and maintaining a path integrity protocol table includes a method <b>410</b> for building and maintaining a GTP path integrity protocol table. The method includes receiving <b>414,</b> a GTP message, extracting <b>418</b> path information from the GTP message and determining <b>422</b> if the extracted path is already included in the path integrity protocol table. If <b>422</b> the path integrity protocol table already includes an entry for the extracted path, the status information for that path is updated <b>430</b> based on path status information that was extracted <b>418</b> from the GTP message. If <b>422,</b> the path is not already included in the path integrity protocol table, a record is added <b>426</b> including an extracted <b>418</b> path definition and related path status information. For example, the reception of the GTP message indicates that the path is administratively unlocked and operationally enabled.

Path status information can be extracted <b>418</b> from both received <b>414</b> GTP-C and GTP-U messages. For example, the reception of any GTP message indicates that the associated path is unlocked and enabled. GTP Echo Response, Create PDP Context and other GTP messages include Remote Node Restart Counter entry <b>258</b> information. GTP-C messages from which path information can be extracted <b>418</b> include, but are not limited to, Create PDP Context Request, Create PDP Context Response, Update PDP Context Request, Update PDP Context Response, Delete PDP Context Request and Delete PDP Context Response messages. GTP-U messages from which path status information can be extracted <b>418</b> include GTP User datagrams. GTP Echo Requests and GTP Echo Response messages can be associated with either the control or user planes.

As explained above, receiving <b>318</b> path status information can also include receiving administrative information. For example, a method <b>510</b> for updating administrative state information includes receiving <b>520</b> administrative state information for a path associated with information in a PIP Table and updating <b>530</b> the Administrative State entry for the path. As explained in greater detail below, some embodiments include transmitting <b>540</b> a new message referred to herein as a Gratuitous GTP Echo Response message which includes the value of the Administrative State entry (e.g., <b>242).</b> The Gratuitous GTP Echo Response message is new in the sense that it is transmitted in response to an administrative state change in the transmitting node (from --Unlocked-- to --Locked--) and not in response to a GTP Echo Request message. Additionally, the administrative state within the Gratuitous GTP Echo Response message iscan be inferred by the receiving node from the incrementing of the Restart Counter within the Recovery Information Element within the Gratuitous GTP Echo Response message. Alternatively, a proprietary version of a Gratuitous GTP Echo Response message using a private extension information element can be used to carry an explicit administrative state field.

For instance, during a system provisioning or maintenance processes, craft personnel install, remove, test or repair resources associated with a node. The node is informed, either through manual entry through a user interface or automatically through "plug-and-play" mechanisms whereby the installation or deinstallation of resources is automatically sensed. By one of these mechanisms, or others, the node is informed that paths associated with the resource are to be locked. The node then looks for entries <b>214</b> in the PIP Table <b>210</b> that are associated with the resource being acted upon by craft. The node then updates <b>530</b> the related Administrative State entries <b>242,</b> setting their values to --Locked-- or --Unlocked- as is appropriate for the actions of craft. In some embodiments, when the state change is to --Locked- the node transmits a Gratuitous GTP Echo Response message to nodes associated with the newly locked paths. The Gratuitous GTP Echo messages include updated (incremented) Restart Counter information within the Recovery information element. Receiving nodes can take note of the changed Restart Counter information (by comparing it with Restart Counter <b>258</b> information stored in their respective local PIP tables <b>210)</b> and tear down or clean up associated PDP Contexts and update their respective PIP tables <b>210</b> accordingly.

The PIP Table <b>210</b> for which updating <b>530</b> has been described is for the local node. In some embodiments, the method <b>510</b> includes informing remote nodes of the administrative state of the local node so that the remote nodes may update PIP Tables of their own. As mentioned above, in these embodiments, the local node transmits the new message referred to herein as a Gratuitous GTP Echo Response message. The Gratuitous GTP Echo Response message can be identical in form to a GTP Echo Response message. However, a Gratuitous GTP Echo Response message is not transmitted in response to a GTP Echo Request message. Instead, a Gratuitous GTP Echo Response message is transmitted in response to a change in an administrative state of one or more resources of the local node. Where appropriate, a plurality of Gratuitous GTP Echo Response messages are transmitted <b>540,</b> informing one or more of the remote nodes of the administrative state change to associated paths. For example, administrative state information can be inferred by a receiving node from a comparison of the Restart Counter within the Recovery Information Element within the Gratuitous GTP Echo Response message and a Restart Counter value stored in a PIP table in the local or receiving node. Alternatively, the Gratuitous GTP Echo Response message can be a proprietary version of a Gratuitous GTP Echo Response message including a private extension field information element for explicitly communicating the administrative state of a transmitting node or path. Of course, in embodiments that include the Gratuitous GTP Echo Response Message Transmission <b>540,</b> when remote nodes undergo administrative state changes, they too transmit Gratuitous GTP Echo Response messages to the local node. It should be understood that such Gratuitous GTP Echo Response messages are to be included in the GTP messages that can be received <b>414</b> and from which path information can be extracted <b>418</b> and used to update <b>430</b> or add <b>426</b> path record information.

Referring to FIG. 6, a method <b>610</b> for further maintaining a Path Integrity Protocol Table (e.g., <b>210)</b> includes monitoring the age of status information in the table. When status entries for a path become stale or have an age beyond a desired age threshold or refresh time, updated information is requested. If updating information is not received, the Operational State entry <b>246</b> associated with the path (e.g., <b>214, 218)</b> is updated to have a value of --Disabled--. If the path remains disabled for an extended period of time, or time beyond a disabled time threshold, the path entry <b>214</b> and associated state information <b>222</b> are removed or flushed from the PIP table.

For example, referring to FIG. 6, a method <b>610</b> for further maintaining a Path Integrity Protocol Table (e.g., <b>210)</b> includes waiting <b>614</b> for a pole timer to expire. When the pole timer expires <b>614,</b> a determination <b>618</b> is made as to whether or not a first dynamic path record is older than a desired age, record age threshold or refresh time. For example, the Time Stamp entry <b>250</b> for the record is examined or compared with a current time. If the difference between the current time and the value of the Time Stamp entry <b>250</b> is greater than a path status information age threshold or refresh time, a GTP Echo Request message is transmitted <b>622</b> over the dynamic path associated with the record. If <b>624</b> a response is received (i.e., GTP Echo Response), the operational state entry for the path record is updated 626 to a value of --Enabled-, a determination <b>627</b> is made as to whether or not all records have been examined and if not, a next record is selected <b>628</b> for examination. If <b>627,</b> all the records (e.g., <b>214)</b> in the PIP Table have been examined, the poll timer is reset <b>629.</b>

In this way, once a dynamic path is included in a PIP Table, a node can be aware of and maintain status information for the path, even when the path has no active PDP contexts associated with it. This allows network operations, such as call processing and OAM functions to select paths that are known to be available instead of blindly selecting paths under only an assumption that the paths are available. Once the operational state of the path is updated to <b>626,</b> the next record is selected <b>628</b> for processing.

If no response is received, processing waits <b>630</b> until a response timer expires. When the response timer expires, a retry timer is incremented <b>632.</b> When the retry counter is incremented, a determination <b>634</b> is made as to whether a retry count limit is exceeded. If the retry count limit is not exceeded, the operational state of the path record is updated <b>636</b> to a value of -Unknown-- and a new GTP Echo Request message is transmitted <b>622.</b>

If <b>634</b> the retry count is exceeded, a determination <b>640</b> is made as to whether the operational state entry <b>246</b> of the record is already set to --Disabled-. If the operational state entry <b>246</b> of the record was not already set to --Disabled-, the operational state of the dynamic path record is set <b>644</b> to -Disabled- and the Path Disabled Time entry <b>254</b> is set equal to the current time or to a time associated with the first determination that the path is disabled. When the operational state <b>246</b> and Path Disabled Time entry <b>254</b> is properly set, the determination <b>627</b> is made as to whether all records have been examined. If all the records have not been examined then the next record is selected <b>628.</b> If <b>627</b> all the records have been examined, the poll timer is reset <b>629.</b>

If <b>640</b> the Operational State entry <b>246</b> for the path was already set to --Disabled--, then a determination <b>650</b> is made as to whether the path has been disabled for a period longer than a disabled path time limit. For example, the Path Disabled Time entry <b>254</b> for the record is compared to the current time. If the difference between the Path Disabled Time entry <b>254</b> and the current time is greater than the disabled path time limit, the record is deleted <b>654</b> or flushed from the Path Integrity Protocol Table (e.g., <b>210).</b> When the record is deleted <b>654,</b> the determination <b>627</b> is made as to whether all records have been examined and processing continues as described above. If <b>650</b> the path has not been disabled longer than the disabled path time limit, no deletion takes place and again the determination of <b>627</b> is made as to whether all records have been examined and processing continues as described above.

A network node operative to implement the Path Integrity Protocol includes main network node functional blocks for carrying out the main purpose or function of the network node. Additionally, a network node operative to carry out the Path Integrity Protocol includes a GTP Echo Request/Response Processor and a Path Integrity Protocol module or functional equivalents thereof. Each of the main network node functional blocks, the GTP Echo Request/Response Processor and the Path Integrity Protocol Module can be implemented in software, hardware or a combination of software and hardware. The use of the term --processor-- is not meant to suggest a hardware implementation. The GTP Echo Request/Response Processor, as well as the other functional blocks, can be implemented as process, processes or one or more sets of sub-processes distributed over a plurality of hardware or software modules.

A GTP Echo Request/Response Processor (e.g., <b>154)</b> is operative to transmit GTP Echo Requests in a UMTS/GPRS network when directed to do so by other components of the network node. Additionally, a GTP Echo Request/Response Processor is operative to receive and process GTP Echo Response messages received from the other nodes in the network as directed by the other components or modules of the network node.

The Path Integrity Protocol module is operative to build a Path Integrity Protocol table (e.g., <b>210)</b> by extracting (e.g., <b>418)</b> Path Integrity Information from network message traffic associated with the node and recording (e.g., <b>426)</b> the extracted information in the Path Integrity Protocol table (e.g., <b>210).</b> The Path Integrity Protocol module is also operative to update (e.g., <b>430)</b> the information recorded in the table by extracting (e.g., <b>418)</b> updated Path Integrity Information from additional network message traffic associated with a node and recording (e.g., <b>430)</b> the extracted updated information in the table (e.g., <b>210).</b> Furthermore, the Path Integrity Protocol module is operative to monitor (e.g., <b>618)</b> the age of the recorded information stored in the table and to update old information in the table by directing the GTP Echo Request/Response Processor to transmit (e.g., <b>622)</b> GTP Echo Requests over paths associated with old table information and to provide information to the Path Integrity Protocol module (e.g., <b>624, 634, 640)</b> regarding the reception or lack of reception of GTP Echo Response messages associated with the GTP Echo Requests. The Path Integrity Protocol module is then further operative to replace (e.g., <b>626, 636, 644)</b> the old recorded information with new information based on the information provided to the Path Integrity Protocol module by the GTP Echo Request/Response Processor.

In some embodiments, the Path Integrity Protocol module is further operative to delete (e.g., <b>654)</b> dynamic path information from the Path Integrity Protocol Table (e.g., <b>210)</b> when (e.g., <b>650)</b> for longer than a path disabled time or duration limit.

In some embodiments, the Path Integrity Protocol module is further operative to build and maintain the Path Integrity Table (e.g., <b>210)</b> by accepting manual path definition entries and including and/or updating records in the Path Integrity Protocol Table based on those mafiual path information entries. For example, in some embodiments the Path Integrity Protocol module is operative to accept manually entered administrative state information associated with the path definition record (e.g., <b>214, 218)</b> and update the Administrative State entry (e.g., <b>242)</b> in the Path Integrity Protocol Table (e.g., <b>210).</b>

In some embodiments the Path Integrity Protocol module is further operative to transmit a Gratuitous GTP Echo Response message indicating the new value of a restart counter of the node or path. Administrative State entry <b>242</b> information associate with the path can be inferred and updated by receiving nodes. The nodes compare the Restart Counter information received in the Gratuitous GTP Echo Response message with Restart Counter <b>258</b> previously stored in the PIP table. If the received Restart Counter information is different, the receiving node can infer that the administrative state of the associated path has been changed to --Locked-- and can update its local PIP table and take other appropriate actions.

Referring to FIG. 7, an exemplary portion <b>710</b> of network operative to perform the Path Integrity Protocol includes a plurality <b>714</b> of network nodes. For instance, the plurality of network nodes are UMTS/GPRS network nodes. For example, the exemplary portion <b>710</b> of a network includes an RNC <b>718,</b> a first SGSN <b>722,</b> a first GGSN <b>726,</b> a second SGSN <b>730,</b> and a second GGSN <b>734.</b>

Each network node (e.g., <b>718, 722, 726, 730, 734)</b> includes a Path Integrity Protocol module <b>738</b> and a GTP Echo Request/Response Processor <b>742.</b> Additionally, each network node (e.g., <b>718, 722, 726,730, 734)</b> includes main network node functional blocks for carrying out the main function of the node.

For example, the RNC <b>718</b> includes Radio Node Controller Functional Blocks <b>750,</b> at least some of which are adapted to take advantage of the information (e.g., <b>218, 222)</b> collected by the Path Integrity Protocol module <b>738</b> and stored by the Path Integrity Protocol module <b>738</b> in a Path Integrity Protocol table <b>752</b> of the RNC <b>718.</b> For instance, call processing and OAM main RNC functional blocks are adapted to take advantage of the RNC PIP Table <b>752</b> to improve the efficiency of Call Processing and OAM functions.

As explained above, the Path Integrity Protocol module <b>738</b> builds the Path Integrity Protocol table <b>752</b> of the RNC <b>718</b> by extracting 418 Path Integrity Information from network message traffic received <b>414</b> by the RNC <b>718.</b> The Path Integrity Protocol module <b>738</b> uses the extracted information to either build or add <b>426</b> to the table <b>752,</b> when the extracted information is related to a path for which status information is not already recorded in the table <b>752,</b> or the extracted information is used to update <b>422</b> records for paths that have entries (e.g., <b>214)</b> in the Path Integrity Protocol Table <b>752</b> of the RNC <b>718.</b> Additionally, the Path Integrity Protocol module <b>738</b> of the RNC <b>718</b> monitors <b>618</b> the age of the recorded information stored in the table and updates (e.g., <b>626, 636, 644)</b> old information in the table by directing the GTP Echo Request/Response Processor <b>742</b> of the RNC <b>718</b> to transmit (e.g., <b>622)</b> Echo Request messages over the paths associated with the old information and to provide information to the Path Integrity Protocol module <b>738</b> of the RNC <b>718</b> regarding the reception or lack of reception <b>624</b> of GTP Echo Response messages associated with the GTP Echo Requests. The Path Integrity Protocol module then updates (e.g., <b>626, 636, 644)</b> the old recorded information with new information based on the information provided by the GTP Echo Request/Response Processor <b>742</b> of the RNC <b>718.</b>

The Path Integrity Protocol module <b>738</b> can build and maintain the Path Integrity Protocol Table (e.g., <b>752)</b> by extracting Path Integrity Information from any of a large number of GTP-U and GTP-C messages. For example, the Path Integrity Protocol module <b>738</b> can extract path integrity information from received <b>414</b> GTP-U (user plane) datagrams or Packet Data Units (PDU), Create PDP Context Request messages, GTP Echo Request messages, GTP Echo Response messages, Create PDP Context Response messages, Update PDP Context Request Messages, and Update PDP Context Response messages. As explained, in reference to FIG. 2, the extracted information that is stored and updated in the Path Integrity Protocol Table <b>752</b> of the RNC <b>718</b> includes a path definition including a first or local node IP address <b>226,</b> a second or Remote Node IP address <b>230</b> and a port number <b>234</b> as well as status or state information (e.g., <b>222)</b> associated with that path definition <b>218.</b> Depending on the point of reference and whether one is referring to a transmitted or received message the Local and Remote Node IP addresses are alternately referred to as source and/or destination addresses.

The status or state information includes an operational state <b>246</b> which can be determined or inferred from the reception of messages over the path or from the lack of response to the transmission (e.g., <b>622)</b> of a GTP Echo Request message. The status information also includes a Time Stamp (e.g., <b>250)</b> indicating the freshness of the state information <b>222.</b>

Optionally, the Path Integrity Protocol module infers or extracts <b>418</b> administrative state information (e.g., <b>242)</b> from received <b>414</b> messages. For instance, the Path Integrity Protocol modules <b>738</b> of the plurality <b>714</b> of modules receive <b>520</b> administrative state information and update 530 their respective Path Integrity Protocol Tables (e.g., <b>752, 756, 760, 764, 768).</b> When this occurs, the respective remote nodes (e.g., <b>722, 726, 730, 734)</b> transmit <b>540</b> Gratuitous GTP Echo Response messages including updated Restart Counter information which, as explained above, can be used to update information in PIP tables. The local node (in this example the RNC <b>718)</b> receives <b>414</b> the Gratuitous GTP Echo Response messages and the Path Integrity Protocol module <b>738</b> of the local node (or RNC <b>718)</b> infers or extracts <b>418</b> the path and administrative state information and stores the administrative state information in the Path Integrity Protocol Table <b>752</b> in association with the appropriate path (e.g., <b>218, 214).</b> For instance, because the remote node is known to be administratively --Locked--, the Path Integrity Protocol module <b>738</b> of the local node sets the Operational State values <b>246</b> of paths associated with the remote node to a value of --Disabled-- in the PIP table of the local node.

In some embodiments, the Administrative State <b>242</b> information is related only to the local node and is received <b>520</b> from craft personal working with the node and is only used to update <b>530</b> configuration information and the Path Integrity Protocol Table <b>752</b> of the local node (e.g., RNC <b>718).</b>

In some embodiments, the Path Integrity Protocol module <b>738</b> is operative to receive or determine and store a path type (e.g., <b>238).</b> For instance, craft personnel may identify static and dynamic paths during a commissioning or provisioning process. Additionally, dynamic paths are identified by the Path Integrity Protocol Module <b>738</b> via Path Information Extraction <b>418</b> based on the reception <b>414</b> of regular network message traffic.

As explained above, some embodiments extract <b>418</b> remote node Restart Counter information (e.g., <b>258)</b> from received <b>414</b> network message traffic. In those embodiments, the remote node Restart Counter is added <b>426</b> to or updated <b>430</b> in the Path Integrity Protocol table (e.g., <b>752)</b> of the local node (e.g., <b>718).</b>

In some embodiments, as part of the PIP Table maintenance procedure, the Path Integrity Protocol module <b>738</b> deletes entries (e.g., <b>214)</b> associated with paths that have Operational State entries <b>246</b> of -- Disabled-- for longer than a disabled path duration or time limit. When it is first determined <b>640</b> that a path is disabled, the Path Integrity Protocol module <b>738</b> records a time associated with that determination as a Path Disabled Time (e.g., <b>254)</b> in the record (e.g., <b>214)</b> associated with the path. If 650 the path remains disabled for longer than a disabled path time limit or duration the Path Integrity Protocol module <b>738</b> deletes <b>654.</b> The information (e.g., <b>214)</b> related to the disabled path from the Path Integrity Protocol table.

The Path Integrity Protocol modules <b>738</b> of other network nodes (e.g., <b>722, 726, 730, 734)</b> provide functions similar to those described in reference to the Path Integrity Protocol module <b>738</b> of the RNC <b>718.</b> Of course, instead of including main RNC network node functional blocks, the SGSNs (e.g., <b>722, 730)</b> include main SGSN network node functional blocks <b>780</b> and the GGSNs (e.g., <b>726, 734)</b> include main GGSN network node functional blocks 784. At least some of the SGSN 780 and GGSN <b>784</b> functional blocks are adapted to take advantage of their associated Path Integrity Protocol Tables <b>756, 764, 760 and 768</b> respectively. For example, call processing and OAM functional blocks (not shown) of the SGSNs (e.g., <b>222, 230)</b> and the GGSNs (e.g., <b>226, 234)</b> are adapted to select enabled and unlocked paths based on information in the tables (e.g., <b>756, 764, 760, 768)</b> for use in call processing and OAM functions.

The invention has been described with reference to preferred embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the present specification. It is intended that the invention be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.