GB2536484A

GB2536484A - Data routing

Info

Publication number: GB2536484A
Application number: GB1504685.7A
Authority: GB
Inventors: James Springett Phillip; Dymond Max; Peter Norris Ryan; Edward Pratt Oliver; Malcolm Gilbert George
Original assignee: Metaswitch Networks Ltd
Current assignee: Metaswitch Networks Ltd
Priority date: 2015-03-19
Filing date: 2015-03-19
Publication date: 2016-09-21
Anticipated expiration: 2035-03-19
Also published as: GB2536484B; US10057160B2; US20160277285A1; GB201504685D0

Abstract

Communications network route finding algorithm wherein a route request (RReq) message specifying a desired destination (e.g. B) is transmitted from source node (A). A single next hop (e.g. Route 1) is selected and the RReq is unicast over it. In the event that the RReq is unsuccessful another next hop is selected. Rather than simply try routes in numerical order (1, 2, 4, 5 see Fig. 3) the invention selects a new route which has different characteristics to that which has failed (e.g. route 4 in a different domain, see Fig. 4).

Description

Data Routine

Technical Field

The present invention relates to data routing. In particular, but not exclusively, the present invention relates to routing data in a data communications network.

Background

A network element (or 'network node') can use normal "Hunting" to try different routes to a destination, one after another, until one succeeds. Broadly, the network element selects a route from a routing table and attempts to use that route. If that route fails, the network element performs another lookup in the routing table to find the "next" route to try. This happens repeatedly until the selected route succeeds (or the network element runs out of routes to try, and the routing is failed).

Summary

According to a first aspect of the present invention, there is provided a method of routing data in a data communications network, the method comprising: receiving a request to route data to a given destination in the network; first selecting a first route to the given destination from a plurality of routes to the given destination stored in a routing table; attempting to route the data to the given destination using the first selected route; in response to receipt of an indication that routing the data to the given destination via the first route failed, second selecting a second, different route to the given destination from the plurality of routes to the given destination stored in the

routing table,

wherein the second selecting comprises omitting, for the purposes of the second selection, at least one route to the given destination from the plurality of routes to the given destination stored in the routing table, the omitting being carried out at least in part on the basis of the at least one route having at least one characteristic in common with the first route; and attempting to route the data to the given destination using the second selected route According to a second aspect of the present invention, there is provided apparatus for use in routing data in a data communications network, the apparatus being configured to: receive a request to route data to a given destination in the network; first select a first route to the given destination from a plurality of routes to the given destination stored in a routing table; attempt to route the data to the given destination using the first selected route; in response to receipt of an indication that routing the data to the given destination via the first route failed, second select a second, different route to the given destination from the plurality of routes to the given destination stored in the routing

table,

wherein the second selecting comprises omitting, for the purposes of the second selection, at least one route to the given destination from the plurality of routes to the given destination stored in the routing table, the omitting being carried out at least in part on the basis of the at least one route having at least one characteristic in common with the first route; and attempt to route the data to the given destination using the second selected route. According to a third aspect of the present invention, there is provided a computer program adapted to perform a method of routing data in a data communications network, the method comprising: receiving a request to route data to a given destination in the network; first selecting a first route to the given destination from a plurality of routes to the given destination stored in a routing table; attempting to route the data to the given destination using the first selected route; in response to receipt of an indication that routing the data to the given destination via the first route failed, second selecting a second, different route to the given destination from the plurality of routes to the given destination stored in the routing table, wherein the second selecting comprises omitting, for the purposes of the second selection, at least one route to the given destination from the plurality of routes to the given destination stored in the routing table, the omitting being carried out at least in part on the basis of the at least one route having at least one characteristic in common with the first route; and attempting to route the data to the given destination using the second selected route.

According to a fourth aspect of the present invention, there is provided apparatus substantially in accordance with any of the examples as described herein with reference to and illustrated by the accompanying drawings.

Embodiments comprise a computer program product comprising a non-transitory computer-readable storage medium having computer readable instructions stored thereon, the computer readable instructions being executable by a computerized device to cause the computerized device to perform a method of routing data in a data communications network, the method comprising: receiving a request to route data to a given destination in the network; first selecting a first route to the given destination from a plurality of routes to the given destination stored in a routing table; attempting to route the data to the given destination using the first selected route; in response to receipt of an indication that routing the data to the given destination via the first route failed, second selecting a second, different route to the given destination from the plurality of routes to the given destination stored in the

routing table,

wherein the second selecting comprises omitting, for the purposes of the second selection, at least one route to the given destination from the plurality of routes to the given destination stored in the routing table, the omitting being carried out at least in part on the basis of the at least one route having at least one characteristic in common with the first route; and attempting to route the data to the given destination using the second selected route Further features and advantages of the invention will become apparent from the following description of preferred embodiments of the invention, given by way of example only, which is made with reference to the accompanying drawings.

Brief Description of the Drawings

Figure 1 shows a system diagram according to embodiments; Figure 2 shows a tree structure according to embodiments; Figure 3 shows a tree structure according to embodiments; and Figure 4 shows a tree structure according to embodiments.

Detailed Description

Figure 1 shows a system diagram of a network 100 according to embodiments. In Figure 1, network element A is trying to route data to a destination in the network, in this case network element B. Network element A has a choice of four possible routes to try; two routes via Domain X (routes 1 and 2), and two routes via Domain Y (routes 4 and 5). Network element A comprises a processor (or 'processing system') for performing various data processing tasks according to embodiments. Network element A comprises a memory 12A for storing data such as routing table data.

Figure 2 shows a tree structure according to embodiments. In particular, Figure 2 shows a representation of a routing table having a plurality of routes in the form of a tree structure comprising a plurality of nodes.

In embodiments, network element A is configured with the routing table of Figure 2 (evaluated from top to bottom). Network element A first selects which domain to use, then selects which route within that domain.

Note that the basis on which the selecting decisions are made is not important to the hunting process. As one example, the domain could be determined by an electronic number mapping system (ENUIVI) lookup (which returns an ordered list of domains to try -e.g. X then Y), and the routes within each domain could either be determined by the Name Authority Pointer (NAPTR) records within the ENUM lookup or by some other operator configurable preference (e.g. cost or quality).

According to embodiments, the size and shape of the tree structure is not important. The above example demonstrates various benefits of embodiments of the present invention; as more layers are added and/or more options are added at each layer, embodiments of the invention will equally apply.

According to embodiments, the type of network element type is also not important. In some embodiments, the network element comprises a session border controller (SBC) network element, whereas in other embodiments the same logic could apply to any other network element such as a switch.

Figure 3 shows a tree structure according to embodiments. In particular, Figure 3 shows operation of a 'basic' hunting process on an example routing table.

First (dashed line/arrow), the routing table is traversed and route 1 is selected.

Route 1 is then tried, but fails.

Next, (dotted line/arrow), the routing table is traversed and route 1 is selected. However, route 1 is discounted (i.e. not considered a viable routing option) as having failed, and the process backtracks to the parent node in the tree and selects the next option, which is route 2.

Route 2 is then tried, but fails.

Next, (solid line/arrow), the routing table is traversed and route 1 is selected. However, route 1 is discounted as having failed, and the process backtracks to the parent node in the tree and selects route 2. However, route 2 is discounted as having failed and the process backtracks to the parent node. The parent node has had all its child nodes discounted so the process backtracks again to the next parent node, and then route 4 is selected.

Embodiments comprise improved measures, including methods, apparatus and computer programs for use in data packet routing. Embodiments seek to minimize the number of retries required to find a route that succeeds both to reduce the elapsed time before an attempt succeeds and the amount of processing required to do so. Embodiments introduce a new concept of an "anchor" node which may be operator configurable. For each child node below an anchor node, all the routes are considered "similar" and therefore if one of the routes under the child fails, then all of the routes under that child are likely to fail as well. When hunting, "similar" nodes can therefore be skipped completely to maximize the chance of finding a successful route quickly and with minimal processing effort.

Embodiments comprise measures for use in routing data in a data communications network. Such measures may be referred to as enabling fast fail hunting. At a network element, a request to route data to a given destination in the network is received. The network element first selects a first route to the given destination from a plurality of routes to the given destination stored in a routing table.

The network element then attempts to route the data to the given destination using the first selected route. In response to receipt of an indication that routing the data to the given destination via the first route failed, the network element second selects a second, different route to the given destination from the plurality of routes to the given destination stored in the routing table. In such embodiments, the second selecting comprises omitting, for the purposes of the second selection, at least one route to the given destination from the plurality of routes to the given destination stored in the routing table. The omitting is carried out at least in part on the basis of the at least one route having at least one characteristic in common with the first route. The network element then attempts to route the data to the given destination using the second selected route.

Embodiments comprise representing the plurality of routes to the given destination stored in the routing table as a tree structure comprising a plurality of nodes; in such embodiments, the at least one characteristic in common comprises the representation of the at least one route in the tree structure comprising at least one node which is in common with the representation of the first route in the tree structure. Embodiments comprise representing the plurality of routes to the given destination stored in the routing table as a tree structure comprising a plurality of nodes; in such embodiments, the first selecting comprises a first traversal of the tree structure, the first traversal comprises traversal of at least one predefined anchor node comprised in the plurality of nodes, and the at least one characteristic in common comprises the representation of the at least one route in the tree structure comprising at least one node which is a descendent node of the at least one predefined anchor node.

In embodiments, for each child node below the at least predefined anchor node in the tree structure, all of the routes represented in the tree structure below a respective child node are considered similar such that if one of the routes represented in the tree structure below a respective child node fails, then all of the routes under a respective child node are also likely to fail.

In embodiments, the at least one characteristic in common comprises the representation of the at least one route in the tree structure comprising at least one node which is a child node of the at least one predefined anchor node.

In embodiments, the second selecting comprises a second traversal of the tree structure, and the second traversal comprises traversal to the at least one predefined anchor node, but not to a given child node of the at least one predefined anchor node.

In embodiments, the second selecting comprises a second traversal of the tree structure, and the second traversal comprises traversal to the at least one predefined anchor node, but not to a given child node of the at least one predefined anchor node or to any descendent nodes of the given child node.

Figure 4 shows a tree structure according to embodiments. In particular, Figure 4 shows operation of an improved hunting process on an example routing table.

First (solid line/arrow), the routing table is traversed and route 1 is selected. As part of the traversal, the network element notes the passing of an anchor node and the child node that was selected thereafter (i.e. domain X).

Route 1 is then tried, but fails.

Next (dotted line/arrow), the routing table is traversed and at the anchor node the network element recalls that selecting the domain X child node led to failure and discounts the option to select that child node (and also all of its descendents) in its entirety. It then selects the next available route, which in this example is route 4. In further embodiments, two hunting processes (basic, and improved) can be combined to create powerful new routing configurations by selecting which process to use based on the reason why the previously selected route failed.

Embodiments comprise first determining that the received failure indication is of a first type, wherein the second selecting is carried out at least in part on the basis of the first determination.

Embodiments comprise second determining that the received failure indication is of a second type, and in response to the second determination, overriding the omitting such that the at least one route is not omitted for the purposes of the second selection. In embodiments, the received failure indication of the first type comprises an indication that there is a connectivity problem with a given domain in the network. In some such embodiments, the received failure indication of the first type comprises a Session Initiation Protocol (SIP) 404 'Not found' response code.

In embodiments, the received failure indication of the second type comprises an indication that there is a connectivity problem with a given server in the network. In some such embodiments, the received failure indication of the second type comprises a Session Initiation Protocol (SIP) 503 'Service unavailable' response code.

For example, when routing SIP messages, if the selection of route 1 led to a SIP 503 ("Service unavailable") response code, this may be indicative of server X1 undergoing maintenance or being temporarily overloaded such that attempting route 2 (via server X2) may well succeed. In this scenario basic hunting may be appropriate. If however, the selection of route 1 led to a SIP 404 ("Not found") response code, this may be indicative of a much wider problem with Domain X's connectivity to the destination network element B. In this scenario, basic hunting would not be appropriate (as route 2 is likely to fail) and it would be more efficient to use the fast fail hunting and immediately move on to trying route 4 via domain Y. In embodiments, the first route, the second route and the at least one route are logically distinct from each other.

In embodiments, the routes under an anchor node are all logically distinct.

Embodiments involve detecting routing failures on one or more distinct routes and recovering by trying another distinct route, having bypassed other routes which are assumed will also fail. Note that such bypassed routes may not necessarily fail, but embodiments take a gamble and decide to move on to try other route(s) which, it is presumed, have a better probability of success.

In embodiments, anchor nodes can be configured anywhere in the routing table hierarchy, not just in a leaf node. Embodiments allow routing to continue after a "fast-fail", thus allowing hunting across multiple groups, and more complex set-ups with multiple anchors in the routing tree allowing complex pruning of different branches, and hunting between different sections of the routing hierarchy.

In embodiments, a user (such as a network operator) can mark certain routing decisions as being critical to the routing which implicitly groups together any distinct next-hops below that decision.

Embodiments also allow for more complex scenarios, such as the labelling of multiple nodes within the tree as being "anchors" and/or route selections that are multiply connected (e.g. they can be selected by traversing a routing table in two ways, one of which goes via an "anchor" node, and one of which does not / or does, but via a different "anchor" node).

In embodiments, the predefinition of which node comprises the at least one predefined anchor node is network operator configurable. A network operator can configure more than one anchor point in a representation of a routing table.

One or more of the aspects of the embodiments described herein with reference to the drawings comprise processes performed by one or more network elements or network nodes. In embodiments, the one or more network elements comprise one or more processing systems or processors configured to carry out these processes. In this regard, embodiments may be implemented at least in part by computer software stored in (non-transitory) memory and executable by the processor, or by hardware, or by a combination of tangibly stored software and hardware (and tangibly stored firmware). Embodiments also extend to computer programs, particularly computer programs on or in a carrier, adapted for putting the above described embodiments into practice. The program may be in the form of non-transitory source code, object code, or in any other non-transitory form suitable for use in the implementation of processes according to embodiments. The carrier may be any entity or device capable of carrying the program, such as a RAM, a ROM, or an optical memory device; etc. Memory, as referred to above may comprise any suitable storage medium, including solid-state drives (SSD) or other semiconductor-based RAM; a ROM, for example a CD ROM or a semiconductor ROM; or a magnetic recording medium, for example a floppy disk or hard disk.

The above embodiments are to be understood as illustrative examples of the invention. Further embodiments of the invention are envisaged. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.

Claims

Claims 1 A method of routing data in a data communications network, the method comprising: receiving a request to route data to a given destination in the network; first selecting a first route to the given destination from a plurality of routes to the given destination stored in a routing table; attempting to route the data to the given destination using the first selected route; in response to receipt of an indication that routing the data to the given destination via the first route failed, second selecting a second, different route to the given destination from the plurality of routes to the given destination stored in the routing table, wherein the second selecting comprises omitting, for the purposes of the second selection, at least one route to the given destination from the plurality of routes to the given destination stored in the routing table, the omitting being carried out at least in part on the basis of the at least one route having at least one characteristic in common with the first route; and attempting to route the data to the given destination using the second selected route.
2. A method according to claim 1, comprising: representing the plurality of routes to the given destination stored in the routing table as a tree structure comprising a plurality of nodes, wherein the at least one characteristic in common comprises the representation of the at least one route in the tree structure comprising at least one node which is in common with the representation of the first route in the tree structure.
3. A method according to claim 1 or 2, comprising: representing the plurality of routes to the given destination stored in the routing table as a tree structure comprising a plurality of nodes, wherein the first selecting comprises a first traversal of the tree structure, wherein the first traversal comprises traversal of at least one predefined anchor node comprised in the plurality of nodes, and wherein the at least one characteristic in common comprises the representation of the at least one route in the tree structure comprising at least one node which is a descendent node of the at least one predefined anchor node.
4. A method according to claim 3, wherein for each child node below the at least predefined anchor node in the tree structure, all of the routes represented in the tree structure below a respective child node are considered similar such that if one of the routes represented in the tree structure below a respective child node fails, then all of the routes under a respective child node are also likely to fail.
5. A method according to claim 3 or 4, wherein the at least one characteristic in common comprises the representation of the at least one route in the tree structure comprising at least one node which is a child node of the at least one predefined anchor node.
6. A method according to any of claims 3 to 5, wherein the second selecting comprises a second traversal of the tree structure, and wherein the second traversal comprises traversal to the at least one predefined anchor node, but not to a given child node of the at least one predefined anchor node.
7. A method according to any of claims 3 to 6, wherein the second selecting comprises a second traversal of the tree structure, and wherein the second traversal comprises traversal to the at least one predefined anchor node, but not to a given child node of the at least one predefined anchor node or to any descendent nodes of the given child node.
8. A method according to any preceding claim, comprising first determining that the received failure indication is of a first type, wherein the second selecting is carried out at least in part on the basis of the first determination.
9. A method according to claim 8, comprising second determining that the received failure indication is of a second type, and in response to the second determination, overriding the omitting such that the at least one route is not omitted for the purposes of the second selection.
10. A method according to claim 8 or 9, wherein the received failure indication of the first type comprises an indication that there is a connectivity problem with a given domain in the network.
11. A method according to any of claims 8 to 10, wherein the received failure indication of the first type comprises a Session Initiation Protocol (SIP) 404 'Not found' response code.
12. A method according to any of claims 9 to 11, wherein the received failure indication of the second type comprises an indication that there is a connectivity problem with a given server in the network.
13. A method according to any of claims 9 to 12, wherein the received failure indication of the second type comprises a Session Initiation Protocol (SIP) 503 'Service unavailable' response code.
14. A method according to any preceding claim, wherein the first route, the second route and the at least one route are logically distinct from each other.
15. A method according to any of claims 3 to 14, wherein the predefinition of which node comprises the at least one predefined anchor node is network operator configurable.
16. A method according to any preceding claim, wherein the method is performed by a network element.
17. A method according to claim 16, wherein the network element comprises one or more of a session border controller (SBC) and a switch.
18. Apparatus for use in routing data in a data communications network, the apparatus being configured to: receive a request to route data to a given destination in the network; first select a first route to the given destination from a plurality of routes to the given destination stored in a routing table; attempt to route the data to the given destination using the first selected route; in response to receipt of an indication that routing the data to the given destination via the first route failed, second select a second, different route to the given destination from the plurality of routes to the given destination stored in the routing table, wherein the second selecting comprises omitting, for the purposes of the second selection, at least one route to the given destination from the plurality of routes to the given destination stored in the routing table, the omitting being carried out at least in part on the basis of the at least one route having at least one characteristic in common with the first route; and attempt to route the data to the given destination using the second selected route.
19. A computer program adapted to perform a method of routing data in a data communications network, the method comprising: receiving a request to route data to a given destination in the network; first selecting a first route to the given destination from a plurality of routes to the given destination stored in a routing table; attempting to route the data to the given destination using the first selected route; in response to receipt of an indication that routing the data to the given destination via the first route failed, second selecting a second, different route to the given destination from the plurality of routes to the given destination stored in therouting table,wherein the second selecting comprises omitting, for the purposes of the second selection, at least one route to the given destination from the plurality of routes to the given destination stored in the routing table, the omitting being carried out at least in part on the basis of the at least one route having at least one characteristic in common with the first route; and attempting to route the data to the given destination using the second selected route.
20. Apparatus substantially in accordance with any of the examples as described herein with reference to and illustrated by the accompanying drawings.