Patent Application
20060274646
1. Field of the Invention
The present invention relates to a technology for managing a network connection between different types of networks.
2. Description of the Related Art
A conventional technology has been disclosed in, for example, Japanese Patent Application Laid-Open No. 2002-342253.
In a network-connection management system according to the conventional technology, two arbitrated loops are created and made redundant in order to improve the reliability in an access to the disk apparatus that is connected to a port of the arbitrated loop.
Therefore, even when a failure occurs in a fabric switch of one of the arbitrated loops, the arbitrated loop in which the failure has occurred is isolated and a fabric switch of the other arbitrated loop is used instead, enabling an access to the disk apparatus that is connected to the port.
However, in order to improve the reliability in the access to the disk apparatuses that are connected to ports of the arbitrated loop, the conventional technology requires the creation of a plurality of arbitrated loops, leading to a problem of considerable cost.
Furthermore, in a selection of a master port based on the LIP sequence, since only one master port can exist on a single arbitrated loop, it is not possible to improve the reliability in the access to the disk apparatus connected to the port simply by providing a plurality of fabric switches on the same loop.
When connecting different networks, in addition to reducing the cost for network connection, it is extremely important to improve the reliability in an access to a node (such as a disk apparatus) that is connected to the port of the arbitrated loop.
It is an object of the present invention to at least solve the problems in the conventional technology.
An apparatus according to one aspect of the present invention manages a network connection between different types of networks via a master port. The apparatus includes a failure detecting unit that detects a failure in other apparatus based on a frame for determining the master port transmitted from the other apparatus; and a master-port switching unit that switches, when the failure detecting unit detects a failure in the other apparatus, the master port of the apparatus from a standby state to an operation state.
A method according to another aspect of the present invention, which is for controlling an apparatus for managing a network connection between different types of networks via a master port, includes detecting a failure in other apparatus based on a frame for determining the master port transmitted from the other apparatus; and switching, when a failure is detected in the other apparatus at the detecting, the master port of the apparatus from a standby state to an operation state.
The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings.
Exemplary embodiments of the present invention will be explained in detail below with reference to the accompanying drawings.
A priority is allocated to each of the fabric switches 100 and 200. Networks are connected using the fabric switch having the higher priority, while the fabric switch having the lower priority functions as a repeater.
This arrangement will be explained more specifically with an example in which the priority of the fabric switch 100 is higher than that of the fabric switch 200. Normally, the fabric switch 100 connects a fabric network to the arbitrated loop by using the FL port and an E port (a port for connecting to a fabric network).
On the other hand, the fabric switch 200 having a lower priority normally functions as a repeater for the arbitrated loop, monitors frames on the loop, and detects irregularities in the fabric switch 100.
The fabric switch 200 detects irregularities in the fabric switch 100 during a loop initialization process (LIP) sequence. An LIP sequence is a loop initialization process executed when the status on the arbitrated loop changes. This LIP sequence selects a master port on the loop and sets the address of each NL port.
When the fabric switch 200 detects a failure in the fabric switch 100 during the LIP sequence, it connects the fabric network to the arbitrated loop instead of the fabric switch 100.
Thus, even when a failure occurs in the fabric switch 100, the fabric switch 100 and the fabric switch 200 can easily be switched by using a conventional LIP sequence mechanism, thereby improving the reliability of the arbitrated loop.
The NL port 10 is an apparatus that connects a node (not shown) such as a disk apparatus or a server apparatus to the arbitrated loop. During an LIP sequence, when the NL port 10 receives a LISM frame (the LISM frame is used for selecting a master port between the nodes during the LIP sequence, the LISM is abbreviation for “loop initialization select master”) via a receiver (RX) from the fabric switch 200, the NL port 10 determines whether the received LISM frame is one created by either of the fabric switches 100 and 200.
When the received LISM frame is created by one of the fabric switches 100 and 200, it is transferred without change to the NL port 20 via a transmitter (TX).
On the other hand, when the received LISM frame is not created by one of the fabric switches 100 and 200, the NL port 10 determines whether the received LISM frame has a higher priority than frames created by the NL port 10. If the priority of the received LISM frame is lower than the LISM frame of the NL port 10, the NL port 10 discards the received LISM frame and transmits a LISM frame created by the own port to the NL port 20.
On the other hand, if the received LISM frame has a higher priority than the LISM frame of the NL port 10, the NL port 10 transfers the received LISM frame without change to the NL port 20. Since the explanation of the NL port 10 applies similarly to the NL ports 20 to 40, redundant explanation thereof will be omitted.
The fabric switches 100 and 200 connect fabric networks to the arbitrated loop. Priorities for the fabric switches 100 and 200 are determined in advance. Normally, the fabric switch with the higher priority connects the fabric network and the arbitrated loop, while the fabric switch with the lower priority functions as a repeater. In this embodiment, an example in which the fabric switch 100 has a higher priority than the fabric switch 200 is explained.
Normally, the fabric switch 100 with the higher priority connects the fabric network to the arbitrated loop, while the fabric switch 200 with the lower priority transfers the frames received from the NL port 30 to the NL port 10.
When a failure occurs in the fabric switch 100, the fabric switch 200 connects the fabric network to the arbitrated loop instead of the fabric switch 100.
The E port 210 is used for connecting to a fabric network, and transfers data received from the fabric network to the data transferring unit 230. The E port 210 transmits data obtained from the data transferring unit 230 to predetermined addresses on the fabric network.
The FL port 220 is a master port for connecting the arbitrated loop and the fabric network. When no failure occurs in the fabric switch 100 shown in
The data transferring unit 230 is a processor that, when the FL port 220 is functioning as a master port on the arbitrated loop, transfers information obtained from the E port 210 to the FL port 220 and transfers information obtained from the FL port 220 to the E port 210.
The port control unit 240 is a processor that controls the E port 210 and the FL port 220. More specifically, upon obtaining information from the LIP-execution processing unit 260 indicating that a failure has occurred in the fabric switch 100, the port control unit 240 switches the function of the FL port 220 from a repeater to a master port, and connects the fabric network to the arbitrated network.
When information is obtained from the LIP-execution processing unit 260 indicating that the failure in the fabric switch 100 has been resolved, the port control unit 240 switches the function of the FL port 220 from a master port to a repeater.
The LIP-primitive generating unit 250 is a processor that, when the status of the arbitrated loop changes (for example, when a new NL port is connected to the arbitrated loop), generates an LIP primitive to enable it to join in the loop as a master port. The generation of this LIP primitive initiates an LIP sequence on the arbitrated loop.
The LIP-execution processing unit 260 determines whether a failure has occurred in the fabric switch 100 based on a LISM frame received during the execution of the LIP sequence, and reports the result of this determination to the port control unit 240. After reporting occurrence of the failure in the fabric switch 100 to the port control unit 240, when the LIP-execution processing unit 260 detects that the fabric switch 100 has recovered, it reports that the failure of the fabric switch 100 has been resolved, to the port control unit 240.
Each of the ports (the NL ports 10 to 40 and the fabric switch 200) reports an address, which is allocated in advance or is newly allocated, to the fabric switch 100 (step S102), and the fabric switch 100 identifies the position of each port on the loop (step S103).
The fabric switch 100 then receives a LISM frame from the NL port 20 (step S202) and determines whether the port type of the received LISM frame is 00h (step S203).
If the port type of the received LISM frame is not 00h (step S203, No) the fabric switch 100 discards the LISM frame (step S204) and proceeds to step S202. On the other hand, if the port type of the received LISM frame is 00h (step S203, Yes) the fabric switch 100 determines whether the LISM frame is the same as the one transmitted by the own apparatus (the fabric switch 100) (step S205). If it is the same LISM frame (step S205, Yes), the fabric switch 100 transmits an ARB (F0) to the NL port 40 (step S206).
By transmitting this ARB (F0), the fabric switch 100 informs the other ports (NL ports 10 to 40) that a master port has been selected.
On the other hand, if the received LISM frame is not the same as the one transmitted by the fabric switch 100 (step S205, No), the fabric switch 100 determines whether its own port name is smaller than that of the received LISM frame (step S207). If its own port name is smaller than that of the received LISM frame (step S207, Yes), the fabric switch 100 transmits the received LISM frame to the NL port 40 (step S208). If the port name of the received LISM frame is larger than its own port name (step S207, No), the fabric switch 100 proceeds the processing to step S204 to discard the LISM frame.
In addition to a port type, a LISM frame includes a port name. When the port types of LISM frames are the same, their Priorities are determined by using their port names. In the LIP sequence used in this embodiment, the smaller the value of the port name, the higher the priority.
The NL port 10 then receives a LISM frame from the fabric switch 200 (step S302) and determines whether the port type of this LISM frame is 00h (step S303). If the port type of the received LISM frame is 00h (step S303, Yes) the NL port 10 transmits the received LISM frame to the NL port 20 (step S304).
On the other hand, if the port type of the received LISM frame is not 00h (step S303, No), the NL port 10 determines whether its own port name is smaller than that of the received LISM frame (step S305). If its own port name is smaller (step S305, Yes), the NL port 10 discards the received LISM frame (step S306) and proceeds the processing to step S302. On the other hand, if its own port name is not smaller (step S305, No), the NL port 10 proceeds the processing to step S304.
The port control unit 240 switches the function of the FL port from a repeater to a master port (step S402), and the LIP-primitive generating unit 250 generates an LIP primitive (step S403). The port type of the LISM frame is set to 00h and the LISM frame is transmitted to the NL port 10 (step S404).
The LIP-execution processing unit 260 receives the LISM frame (step S405) and determines whether the port type of the LISM frame is 00h (step S406). When the port type is not 00h (step S406, No), the LIP-execution processing unit 260 discards the received LISM frame (step S407) and proceeds the processing to step S405.
On the other hand, when the received port type is 00h (step S406, Yes), the LIP-execution processing unit 260 transmits an ARB (F0) (step S408).
Thus, when the LIP-execution processing unit 260 detects a failure in the fabric switch 100, the port control unit 240 switches the function of the FL port 220 from a repeater to a master port. Therefore, the fabric network can be connected to the arbitrated loop even when a failure occurs in the fabric switch 100, and the reliability of the arbitrated loop can be improved.
The LIP-execution processing unit 260 then receives a LISM frame (step S502) and determines whether the port type of the LISM frame is 00h (step S503). If the port type is not 00h (step S503, No), the LIP-execution processing unit 260 discards the received LISM frame (step S504) and proceeds the processing to step S502.
On the other hand, when the port type is 00h (step S503, Yes), the fabric switch 200 determines whether the LISM frame is the same as the one transmitted by the own apparatus (step S505), and if so (step S505, Yes), retransmits the LISM frame with a normal port name value (step S506). The fabric switch 200 receives the LISM frame transmitted by the own apparatus (step S507) and transmits an ARB (F0) (step S508).
On the other hand, when the received LISM frame is different from that of the fabric switch 200 (step S505, No), the fabric switch 200 determines whether its own port name is smaller than the port name of the received LISM frame (step S509). If its own port name is smaller (step S509, Yes), the fabric switch 200 proceeds the processing to step S504.
On the other hand, when its own port name is not smaller (step S509, No), the port control unit 240 switches the function of the FL port 220 from a master port to a repeater (step S510), and transmits the LISM frame received by the LIP-execution processing unit 260 to the NL port 10 (step S511).
Thus, when the LIP-execution processing unit 260 detects that the failure in the fabric switch 100 has been resolved, the port control unit 240 switches the function of the FL port from a master port to a repeater, thereby enabling the fabric switch 100 to start operating again efficiently.
At step S505, when the received LISM frame is different from the LISM frame of the own apparatus, i.e., when the received LISM frame has a different port type to the port type generated by the own apparatus, the failure in the fabric switch 100 is determined to have been resolved and the fabric switch 200 switches to a repeater.
At step S501, the fabric switch 200 initially sets the port name to a large provisional value instead of the actual port name in order to ensure that, when the fabric switch 100 where the failure has been resolved receives a LISM frame from the fabric switch 200, the fabric switch 100 surely discards this LISM frame and the fabric switch 200 can reliably receive a LISM frame from the fabric switch 100.
At step S507, since the fabric switch 200 can receive the provisional LISM frame, the fabric switch 200 can reliably determine that the fabric switch 100 is not on the loop. Therefore, the fabric switch 200 retransmits the LISM frame with its actual port name and functions as an FL port.
In the fabric switch 200 according to the present embodiment described above, during the LIP sequence, when the LIP-execution processing unit 260 detects a failure in the fabric switch 100 based on a frame transmitted from the fabric switch 100, the port control unit 240 switches the function of the FL port 220 from a repeater to a master port and connects the fabric network to the arbitrated loop. Therefore, the reliability in access to nodes connected on the arbitrated loop can be improved by using the conventional LIP sequence. Costs can be greatly reduced, since there is no need to establish multiple arbitrated loops as in the conventional technique.
Although the priority of the fabric switch 100 is higher than that of the fabric switch 200 in the present embodiment, the priority of the fabric switch 200 can be higher than that of the fabric switch 100 instead.
If the priority of the fabric switch 200 is higher than that of the fabric switch 100, normally, the fabric switch 200 connects the fabric network and the arbitrated loop while the fabric switch 100 functions as a repeater. When a failure occurs in the fabric switch 200, the fabric switch 100 connects the fabric network and the arbitrated loop instead of the fabric switch 200.
According to the present invention, the reliability in a network connection between different networks can be improved.
Furthermore, other network-connection management apparatus can be recovered easily.
Moreover, the other network-connection management apparatus can be recovered efficiently by using a conventional LIP sequence.
Although the invention has been described with respect to a specific embodiment for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-162814 | Jun 2005 | JP | national |
