Patent Publication Number: US-7724746-B2

Title: Method and system for providing load balanced traffic in redundant infiniband ethernet gateways network

Description:
FIELD OF THE INVENTION 
   The present invention relates to data network management. More specifically, the present invention relates to method and system for providing load balanced data traffic in redundant Infiniband-to-Ethernet gateways in data networks. 
   BACKGROUND 
   Infiniband (IB) is an industry standard channel based architecture that features high speed, low latency interconnects for distributed computing infrastructure. Hosts with infiniband host adapter can be connected by infiniband switch. Infiniband to Ethernet gateway is typically used to connect infiniband network with traditional Ethernet network. 
   For high availability, two or more IB-to-Ethernet gateways can be used in redundant mode. The IB-to-Ethernet gateways can be in active/standby mode where only one gateway is actively handling data traffic. Alternatively, the IB-to-Ethernet gateways may be configured to work in active/active mode where data traffic is load balanced among the IB-to-Ethernet gateways. 
   Broadly, the IB-to-Ethernet gateways are configured as a layer 2bridge, and ARP (Address Translation Protocol) relay is used to bridge the infiniband and the Ethernet networks. Typically, target/destination IP address in ARP request is used to determine which IB-to-Ethernet gateway to handle the data traffic. Further, traffic between a pair of hosts or network devices such as client terminals may use different IB-to-Ethernet gateways depending upon which host initiated the data traffic. 
   Typically, the Ethernet side of the network includes a router as the default router for all IB hosts. IB hosts use the default router as the next hop to communicate with hosts in the other networks. If the IB host initiates the data traffic, the IB host will send ARP request using the router&#39;s IP address as the target IP address. As a result, all IB hosts will result in using the same IB-to-Ethernet gateway to communicate with hosts in the other networks (for example, the hosts on the Ethernet side). 
   In view of the foregoing, it would be desirable to have methods and systems for providing improved data traffic load balancing among redundant IB-to-Ethernet gateways. 
   SUMMARY OF THE INVENTION 
   In accordance with the various embodiments of the present invention, there are provided methods and systems for providing load balanced traffic in redundant IB-to-Ethernet gateways by, for example, maintaining one pair of source and destination IP addresses using a fixed gateway, and avoiding all hosts in the network from using one IB-to-Ethernet gateway in the data network. 
   These and other features and advantages of the present invention will be understood upon consideration of the following detailed description of the invention and the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a block diagram of an overall data network for practicing one or more embodiments of the present invention; 
       FIG. 2  is a flowchart illustrating the overall process for providing load balanced traffic in redundant IB-to-Ethernet gateways of the data network shown in  FIG. 1  in one embodiment of the present invention; 
       FIG. 3  is a flowchart illustrating the load balancing procedure in the redundant IB-to-Ethernet gateways of the data network shown in  FIG. 1  in one embodiment of the present invention; 
       FIG. 4  is a flowchart illustrating the process for generating the ARP request for destination host in the data network shown in  FIG. 1  in one embodiment of the present invention; and 
       FIG. 5  is a flowchart illustrating the process for generating the ARP reply for source host in the data network shown in  FIG. 1  in one embodiment of the present invention. 
   

   DETAILED DESCRIPTION 
     FIG. 1  is a block diagram of an overall data network for practicing one or more embodiments of the present invention. Referring to  FIG. 1 , data network  100  in one embodiment includes Infiniband (IB) host terminals  140 A,  140 B, each operatively coupled to an Infiniband (IB) switch  130 . In one embodiment, the infiniband (IB) switch  130  includes an IB switch fabric configured to connect all IB hosts and network devices with an Infiniband interface. Each of the IB host terminals  140 A,  140 B may include a network device, each of which includes an Infiniband interface to connect to the IB switch  130 . While only two IB host terminals  140 A and  140 B are shown in  FIG. 1 , within the scope of the present invention, more or less numbers of IB host terminals may be provided for practicing one or more embodiments of the present invention. 
   Referring back to  FIG. 1 , also shown in  FIG. 1  is gateway  110  and gateway  120 , each of which are configured to include in IB interface and an Ethernet interface. More specifically, as can be seen from  FIG. 1 , each of the gateway  110  and gateway  120  are operatively coupled to the IB switch  130 . In addition, each of the gateway  110  and gateway  120  are further operatively coupled to an Ethernet switch  150 , where the Ethernet switch  150  is configured as an Ethernet switch fabric to network devices and host terminals with Ethernet interface in the data network  100 . For example, as can be seen from  FIG. 1 , there is provided an Ethernet host terminal  160  which is configured to include an Ethernet interface, and which is configured to operatively couple to the Ethernet switch  150 . 
   Referring again to  FIG. 1 , each IB host terminal  140 A,  140 B, and the Ethernet host terminal  160  maintains an ARP table to map IP addresses, with hardware addresses. That is, the IB host terminal  140 A,  140 B, and the Ethernet host terminal  160  need to have an ARP entry before the respective host terminal can start to send data traffic to a destination host. In the case of a particular IP address for which an ARP entry does not exist, the host terminals are configured to send a broadcast ARP request for the hardware of the particular IP address. 
   For example, in one embodiment, IB host terminal  140 A is configured with an IP address of 1.1.1.1 and a hardware address of H 1 , while IB host terminal  140 B is configured with an IP address of 1.1.1.2 and a hardware address of H 2 . Moreover, the Ethernet host terminal  160  is configures with an IP address of 1.1.1.3 and a hardware address of H 3 . In addition, gateway  110  may be configured with an IP address of 1.1.1.10, and a hardware address of H 10 .IB on the IB interface, and a hardware address of H 10 .Eth on the Ethernet interface, while gateway  120  may be configured with an IP address of 1.1.1.20, with a hardware address of H 20 .IB on the IB interface, and a hardware address of H 20 .Eth on the Ethernet interface. 
   In addition each of the gateways  110 ,  120  are configured to maintain a query table and an address table, where, for each data traffic the query table includes a data traffic identification (ID), a target protocol address (TPA), a source protocol address (SPA), a data traffic port in and port out information, and a status field (Flag). Further, each address table of the gateways  110 ,  120  are configured to maintain, for each data traffic, a corresponding source IP address, source hardware address, the interface port information, and a status field (Flag). As discussed in further detail below, the query table and the address table are updated based on the data traffic received and/or transmitted by the corresponding gateway  110  or gateway  120 . 
   Referring back to  FIG. 1 , in one embodiment, when the IB host terminal  140 A transmits an ARP request packet with a target protocol address (TPA) of 1.1.1.3, a source protocol address (SPA) of 1.1.1.1, and a source hardware address (SHA) of H 1 , the broadcast ARP request packet is switched by the IB switch  130  and sent to both gateway  110  and gateway  120 . The gateways  110  and  120  perform a load balancing algorithm to determine which of the two gateways  110 ,  120  will handle the coming traffic associated with the ARP request packet from the host terminal  140 A. 
   More specifically, in one embodiment of the present invention, the load balancing procedure to determine which gateway will handle the data traffic associated with the received ARP Request packet is determined based on applying a predetermined hash function to the source protocol address and the number of gateways in the Infiniband-to-Ethernet network. For example, referring back to  FIG. 1 , gateway  110  is associated with an identification parameter (ID) of 1, while gateway  120  is associated with an identification parameter (ID) of 0. When the hash function is applied to the source protocol address (SPA) which, in this case would be 1.1.1.1 (for the ARP request packet from the IB host terminal  140 A), an index value between zero and the number of gateways subtracted by one (1) is returned, where the index value corresponds to the identification parameter (ID) of one of the gateways in the network which is configured to handle the data traffic associated with the ARP request packet. 
   For example, in one embodiment, the hash function in one embodiment may include converting the source protocol address(e.g., 1.1.1.1) to a corresponding hexadecimal integer value of 0×01010101, which is divided by the number of gateways, and resulting in a remainder value. That is, the hexadecimal integer value 0×01010101 divided by two (i.e., two gateways  110  and  120 ) returns a remainder of one. Accordingly, the gateway associated with an identification parameter (ID) of one (1) is determined to handle the data traffic associated with the ARP request packet from the IB host terminal  140 A. 
   Referring back to  FIG. 1 , gateway  110  is configured to generate an entry in the address table associated with the received ARP request packet, for example, the source protocol address (SPA) and the source hardware address(SHA). In addition, the gateway  110  is configured to generate an entry in its query table associated with the received ARP request packet, such as, for example, the target protocol address (TPA)(IP address: 1.1.1.3), source protocol address(SPA)(IP address: 1.1.1.1), port out information as Ethernet port, and the port in information as IB port, with the status field (Flag) as “Pending” which is configured to indicate that the associated query is not resolved. In one aspect, when the gateway  110  receives the ARP reply from the destination host (e.g., the Ethernet host terminal  160 ), the status of the query is considered to be resolved. One example of the query table is shown below: 
   
     
       
         
             
           
             
               TABLE 1 
             
           
          
             
                 
             
             
               Gateway 120 Query Table 
             
          
         
         
             
             
             
             
             
             
          
             
               ID 
               TPA 
               SPA 
               Port Out 
               Port In 
               Flag 
             
             
                 
             
             
               1 
               1.1.1.3 
               1.1.1.1 
               Ethernet 
               IB 
               Pending 
             
             
                 
             
          
         
       
     
   
   Referring back to  FIG. 1 , after updating the query table, gateway  110  is configured to transmit the ARP request packet to the Ethernet side with the target protocol address (TPA) of 1.1.1.3, the source protocol address (SPA) of 1.1.1.10, and the source hardware address (SHA) of H 10 Eth. That is, in one embodiment, the source protocol and hardware addresses of the gateway  110  is used as the corresponding source protocol address (SPA) and the source hardware address (SHA) for the ARP request packet to the transmitted to the Ethernet host terminal  160 . 
   Referring again to  FIG. 1 , the Ethernet host terminal  160  in one embodiment is configured to receive the ARP request packet from gateway  110  switched by the Ethernet switch  150 , and to transmit a unicast ARP reply back to the gateway  110  with target protocol information as the IP address of the gateway  110  (for example, TPA of 1.1.1.10), and the source protocol information as the Ethernet host terminal  160  (for example, SPA of 1.1.1.3, and SHA of H 3 ). 
   Upon receipt of the unicast ARP reply from the Ethernet host terminal  160 , the gateway  110  is configured in one embodiment to resolve the associated entry in the query table by updating the status field (Flag)to change from “Pending” to “Resolved”. In addition, the gateway  110  is configured to generate an additional entry in the address table corresponding to the received ARP reply associated with an IP address of 1.1.1.3, and the hardware address of H 3 . An example of the address table is shown below: 
   
     
       
         
             
           
             
               TABLE 2 
             
           
          
             
                 
             
             
               Gateway 110 address table 
             
          
         
         
             
             
             
             
             
          
             
               ID 
               IP Address 
               Hardware Address 
               Port 
               Flag 
             
             
                 
             
             
               1 
               1.1.1.1 
               H1 
               IB 
               0 
             
             
               2 
               1.1.1.3 
               H3 
               Ethernet 
               0 
             
             
                 
             
          
         
       
     
   
   Referring back again to  FIG. 1 , after updating the address table, gateway  110  in one embodiment is further configured to transmit the ARP reply received from the Ethernet host terminal  160  to the IB host terminal  140 A with a target protocol address of the IB host terminal  140 A (TPA: 1.1.1.1), and source protocol address of the Ethernet host terminal  160  (SPA: 1.1.1.3), and source hardware address of the gateway  110 (SHA: H 10 IB). The IB terminal  140 A then receives the ARP reply from the gateway  110  and is configured to generate an ARP entry associated with the IP address and hardware address of the received ARP reply. 
   That is, in one embodiment, the ARP table of the host terminal  140 A is updated in one embodiment to include an entry associated with initial ARP request packet to include an IP address of the destination IP address (for example, the IP address of the Ethernet host  160 ), and the gateway  110  hardware address (for example, H 10 .IB). In this manner, data traffic from the IB host terminal  140 A to the Ethernet host  160  is configured in one embodiment to use the hardware address H 10 .IB. An example of the ART table for the host terminal  140 A is shown below in Table 3. 
   
     
       
         
             
           
             
               TABLE 3 
             
           
          
             
                 
             
             
               IB Host Terminal ARP Table 
             
          
         
         
             
             
             
          
             
               ID 
               IP Address 
               Hardware Address 
             
             
                 
             
             
               1 
               1.1.1.3 
               H10.IB 
             
             
                 
             
          
         
       
     
   
   Referring yet again to  FIG. 1 , in the case where the Ethernet host  160  initiates data traffic destined for IB host terminal  140 A, the Ethernet host terminal  160  is configured to transmit an ARP request packet with the target protocol address (TPA) of the IB host terminal (TPA: 1.1.1.1), along with its source packet address (SPA: 1.1.1.3), and hardware address (SHA: H 3 ) information. The ARP request packet broadcast by the Ethernet host terminal  160  is switched by the Ethernet switch  150  and reaches both gateway  110  and gateway  120 . 
   Again, gateway  110  and gateway  120  perform a load balancing routine to determine which gateway will handle the data traffic associated with the ARP request packet from the Ethernet host terminal  160 . That is, in one embodiment, since the data traffic associated with the ARP request packet is received at the Ethernet port of the gateway  110  and gateway  120 , the destination IP address associated with the ARP request packet (for example, IP address of the IB host terminal,  140 A-1.1.1.1) is used to determine which of the two gateways  110  and  120  will handle the associated data traffic. As in the previous example above, in one embodiment, apply the hash function described above, since the IP address of the IB host terminal  140 A (IP: 1.1.1.1) corresponds to the hexadecimal integer value 0×01010101 which, when divided by the number of gateways (two in this case), returns a remainder value of one (1), the gateway associated with an identification parameter (ID) corresponding to the remainder value of one (1) is determined to handle the associated data traffic. That is, gateway  110  which as associated with the ARP request packet, and the gateway  120  is configured to drop the ARP request packet. 
   Thereafter, gateway  110  is configured to generate an entry in the address table associated with the received ARP request packet from the Ethernet host terminal  160  based on the source IP address (SPA) and the source hardware address (SHA) of the received ARP request packet(for example, SPA: 1.1.1.3, and SHA: H 3 ). In addition, gateway  110  is configured to update its query table to generate a query associated with the received ARP request packet. That is, in one embodiment, an associated query entry is generated which includes, for example, target protocol address (TPA) of the IB host terminal  140 A, the source protocol address (SPA) of the Ethernet host terminal  160 , the pot out information as the IB port, the port in information as the Ethernet port, and the status field (Flag) as “Pending”. An example of the query table entry is shown below: 
   
     
       
         
             
           
             
               TABLE 4 
             
           
          
             
                 
             
             
               Gateway 110 Query Table 
             
          
         
         
             
             
             
             
             
             
          
             
               ID 
               TPA 
               SPA 
               Port Out 
               Port In 
               Flag 
             
             
                 
             
             
               1 
               1.1.1.1 
               1.1.1.3 
               IB 
               Ethernet 
               Pending 
             
             
                 
             
          
         
       
     
   
   Furthermore, the gateway  110  is configured to broadcast the ARP request to the associated IB host terminal  140 A, where the ARP request includes target protocol address of the IB host terminal  140 A (TPA: 1.1.1.1), and the source protocol address (SPA) of the gateway  110  (SPA: 1.1.1.10), and the source hardware address of the gateway  110  (SHA: H 10 ). The IB host terminal  140 A is configured in one embodiment to receive the broadcast ARP request from the gateway  110 , and to transmit a unicast ARP reply back to gateway  110 , where the unicast ARP reply is associated with a target protocol address (TPA) of the gateway  110  (TPA: 1.1.1.10), and the source protocol address (SPA) and hardware address (SHA) of the IB host terminal  140 A (for example, SPA: 1.1.1.1, and SHA: H 1 ). 
   The gateway  110  in one embodiment is configured to receive the ARP reply from the IB host terminal  140 A and to resolve the associated entry in the query table by, for example, setting the status field (Flag) to “0”. In addition, the gateway  110  is configured to update the address table associated with the ARP reply from the IB host terminal  140 A, for example, having an IP address of 1.1.1.1 and the hardware address of H 1 . An example of the address table for the gateway  110  is shown below: 
   
     
       
         
             
           
             
               TABLE 5 
             
           
          
             
                 
             
             
               Gateway 110 Address Table 
             
          
         
         
             
             
             
             
             
          
             
               ID 
               IP Address 
               Hardware Address 
               Port 
               Flag 
             
             
                 
             
             
               1 
               1.1.1.3 
               H3 
               Ethernet 
               0 
             
             
               2 
               1.1.1.1 
               H1 
               IB 
             
             
                 
             
          
         
       
     
   
   Moreover, the gateway  110  is further configured to send the ARP reply from the IB host terminal  140 A to the Ethernet host terminal  160 , with the target protocol address (TPA) of the Ethernet host terminal  160  (TPA: 1.1.1.3), the source protocol address of the IB terminal  140 A (SPA: 1.1.1.1), and the source hardware address (SHA) of the gateway  110  (SHA: H 10 .Eth). The Ethernet host terminal  160  is configured to receive the ARP reply from the gateway  110  which is switched by the Ethernet switch  150 , and thereafter, the generate an ARP entry associated with the received ARP reply, such that subsequent data traffic is configured to use the hardware address of the gateway  110  (H 10 .Eth) to communicate with the IB host terminal  140 A. 
   In this manner, in one embodiment of the present invention, the IP address of the IB side host terminals are used to determine which gateway to handle the traffic regardless of the direction of the data traffic. For example, in one aspect, data traffic originating from the IB side hosts to the Ethernet side, the source IP address is used to determine which gateway will handle the traffic. On the other hand, for data traffic originating from the Ethernet side hosts to the IB side hosts, the destination IP address is used to determine which gateway will handle the traffic. Accordingly, in one embodiment, traffic between a pair of hosts between the IB network and the Ethernet network may be configured to use a fixed Infiniband-to-Ethernet gateway regardless of where the data traffic originates. Accordingly, in accordance with one embodiment of the present invention, load balancing may be achieved in layer two gateway using ARP relay. 
     FIG. 2 . is a flowchart illustrating the overall process for providing load balanced traffic in redundant IB-to-Ethernet gateways of the data network shown in  FIG. 1  in one embodiment of the present invention. Referring to  FIG. 2 , at step  210 , an ARP request from a source host terminal is detected. Thereafter, at step  220 , load balancing is performed based on, for example, the IP address information associated with the received ARP request. After performing load balancing to determine which gateway will handle the data traffic associated with the ARP request from the source host terminal, in one embodiment, a gateway ARP request is generated and transmitted to the destination host. 
   Referring back to  FIG. 2 , in response to the gateway ARP request transmitted to the destination host, at step  240  and ARP reply is received from the destination host associated with the gateway ARP request. Thereafter, at step  250 , a corresponding gateway ARP reply is generated based on the ARP reply received from the destination host, and thereafter, the gateway ARP reply is transmitted to the source host. 
     FIG. 3  is a flowchart illustrating the load balancing procedure in the redundant IB-to-Ethernet gateways of the data network shown in  FIG. 1  in one embodiment of the present invention. Referring to  FIG. 3 , the load balancing procedure of step  220  ( FIG. 2 ) in one embodiment includes determining whether the ARP request is received at the Ethernet port of, for example, the gateways ( 110 ,  120 ). If at step  310  it is determined that the ARP request is received at the Ethernet port of the gateway, at step  320 , the destination IP address of the data traffic associated with the ARP request is determined. Thereafter, at step  330 , the gateway associated with the destination IP address is selected to handle the data traffic associated with the ARP request. 
   Referring back to  FIG. 3 , if at step  310  it is determined that the source ARP request is not received on the Ethernet port of the gateway ( 110 ,  120 ), then at step  340 , the source IP address of the data traffic associated with the ARP request is determined. Thereafter, at step  350 , the gateway associated with the source IP address is determined to handle the data traffic associated with the ARP request. 
     FIG. 4  is a flowchart illustrating the process for generating the ARP request for destination host in the data network shown in  FIG. 1  in one embodiment of the present invention. Referring to  FIG. 4 , at step  410 , upon receipt of the ARP request, the address table of the selected gateway for handling the data traffic associated with the ARP request is updated based on the information associated with the ARP request as discussed above. Thereafter, the query table of the gateway is updated based on the information associated with the ARP request. Thereafter, the gateway ARP request is generated for broadcast to the destination host terminal, where, as discussed above, the gateway ARP request includes in one embodiment, the source protocol address of the gateway for transmission to the destination host terminal. 
     FIG. 5  is a flowchart illustrating the process for generating the ARP reply for source host in the data network shown in  FIG. 1  in one embodiment of the present invention. Referring to  FIG. 5 , at step  510 , the query table of the gateway determined to handle the data traffic associated with the ARP request is updated based on the ARP reply received from the destination host terminal. Thereafter, at step  520 , the address table of the gateway is updated based on information associated with the received ARP reply, and a corresponding gateway ARP reply is generated for broadcast to the source host terminal of the data traffic. For example, in one embodiment, the gateway ARP rely broadcast to the data traffic source host terminal includes the gateway hardware address (GHA), and the source protocol address (SPA) of the destination host terminal, while the target protocol address (TPA) includes the IP address of the source host terminal. 
   In this manner, in accordance with the various embodiments of the present invention, there are provided methods and system for load balancing in layer two gateways using ARP relay. Accordingly, in one embodiment, data traffic between a pair of hosts between the IB network and the Ethernet network may be configured to use a fixed Infiniband-to Ethernet gateway regardless of where the data traffic originates. Within the scope of the present invention, additional number of gateways greater than two may be implemented in the Infiniband-to-Ethernet network, and where load balancing may be performed to select the respective gateway to handle the data traffic associated with the predetermined ARP request packet. 
   Accordingly, a method for providing load balancing in a data network in one embodiment includes detecting a data transmission request, determining a predetermined interface information associated with the data traffic request, and performing load balancing based on the predetermined interface information associated with the data traffic request. 
   In one aspect, the predetermined interface information may include an Internet Protocol (IP) address of a host terminal in an Infiniband network. 
   The step of performing the load balancing may include selecting one or more of a plurality of network gateways to handle the data transmission request, where the one or more pluralities of network gateways may include Infiniband-to-Ethernet gateways. 
   In a further aspect, the data traffic request may include an address translation protocol (ARP) request packet, where the ARP request packet may be associated with a target protocol address, a source protocol address and a source hardware address. 
   In yet a further aspect, the selecting step may include modifying the source protocol address associated with the ARP request packet. 
   The method in a further embodiment may include the step of updating one or more of a query table or an address table associated with a network gateway. 
   Further, in still another aspect, the method may include the step of receiving an address translation protocol (ARP) reply packet, where the ARP request packet may include a unicast reply. 
   Also, the ARP reply packet may be associated with a target protocol address, a source protocol address, and a source hardware address. 
   A system for providing load balancing in an Infiniband-to-Ethernet network in accordance with another embodiment includes a network interface section including a plurality of gateway terminals, each of the plurality of gateway terminals including a respective Ethernet interface and an Infiniband interface, the network interface section further configured to detect a data traffic request, and in accordance therewith, to select one of the plurality of gateway terminals for handling the detected data traffic request based on an Internet Protocol (IP) address associated with an Infiniband network host terminal associated with the data traffic request. 
   The host terminal in one embodiment may be configured to transmit the data traffic request to the network interface section. 
   The Infiniband network host terminal may be configured to receive one or more data associated with the data traffic request. 
   Furthermore, each of the plurality of gateway terminals may be an Infiniband-to-Ethernet gateway terminal. Moreover, in another aspect, non-selected gateway terminals of the plurality of gateway terminals may be configured to enter an inactive mode. 
   The data traffic request may include an address translation protocol (ARP) request packet, where the ARP request packet may be associated with a target protocol address, a source protocol address and a source hardware address. 
   The selected one the plurality of gateway terminals may be configured to modify the source protocol address associated with the ARP request packet. 
   Moreover, the selected one of the plurality of gateway terminals may be configured to update one or more of a query table or an address table associated with the data traffic request. 
   In still another aspect, the system may include one or more Infiniband switch or an Ethernet switch operatively coupled to the network interface section. 
   A system for providing load balancing in a data network in accordance with yet another embodiment includes means for detecting a data transmission request, means for determining a predetermined interface information associated with the data traffic request, and means for performing load balancing based on the predetermined interface information associated with the data traffic request. 
   The various processes described above including the processes performed by the gateway  110 ,  120 , and the IB host terminals  140 A,  140 B, the Ethernet host  160 , the IB switch  130 , and the Ethernet switch  150 , in the software application execution environment in the data network  100  including the processes and routines described in conjunction with  FIGS. 2-5 , may be embodied as computer programs developed using an object oriented language that allows the modeling of complex systems with modular objects to create abstractions that are representative of real world, physical objects and their interrelationships. The software required to carry out the inventive process, which may be stored in the memory (not shown) of the respective gateway  110 ,  120 , the Ethernet host  160 , the IB switch  130 , and the Ethernet switch  150  may be developed by a person of ordinary skill in the art and may include one or more computer program products. 
   Various other modifications and alterations in the structure and method of operation of this invention will be apparent to those skilled in the art without departing from the scope and spirit of the invention. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. It is intended that the following claims define the scope of the present invention and that structures and methods within the scope of these claims and their equivalents be covered thereby.