In this mode, each of multiple NICs (Network Interface Cards) is connected to a different network. Then, all the NICs are activated and used concurrently. Outgoing packets are assigned to the lines in units of TCP connections.
Thus, different lines are used for different connections for communication. If a failure occurs on one of the lines, communication can continue using another line, offering improved line reliability.
As with Fast switching mode and RIP mode, a virtual interface is created and then a virtual network is allocated to it. A TCP/IP application can carry out communication with the remote system, irrespective of the physical network redundant configuration, by using a virtual IP address set in this virtual interface as its own local system IP address.
Figure 2.17 Example of duplicated operation in GS/SURE linkage mode
Figure 2.18 Example of duplicated operation in GS/SURE linkage mode (TCP relay function)
If the GS/SURE linkage communication function is to be used, the systems among which communication is to be carried out must be connected on the same network. Connecting systems on different networks is not allowed.
If the TCP relay function is to be used, the local system and the remote system on a different network can communicate with each other via SURE.
Lines are used in units of TCP connections for communication. If a failure occurs on a line, processing can continue on another line that is normal. Since all the redundant lines are activated for use, each of the lines can be directly used for a different purpose, enabling efficient use of resources.
GS/SURE linkage mode is appropriate, for example, for communication in a multi-server environment where GS/SURE and GP are mixed or for IP-based reconstruction of network infrastructures of a legacy system.
Figure 2.19 System configuration in GS/SURE linkage mode and Figure 2.20 System configuration in GS/SURE linkage mode (TCP relay function) show a system configuration of GS/SURE linkage mode (GS/SURE communication function) and of GS/SURE linkage mode (TCP relay function), respectively.
Figure 2.19 System configuration in GS/SURE linkage mode
Figure 2.20 System configuration in GS/SURE linkage mode (TCP relay function)
The following explains each component and its meaning:
Indicates a physical interface (such as sha1 and sha2) of the duplicated NIC.
Indicates an IP address to be attached to a physical interface. This IP address is always active. Use the IP address to manage a node by using the cluster operation management view, etc. IPv4 address can be used for a physical interface.
Indicates a virtual interface (such as sha0) used to handle duplicated NICs as one NIC.
Indicates a local IP address to be attached to a virtual interface for communication with remote devices. This IP address is activated on the active node. In cluster operation, the IP address is taken over by the standby node when clusters are switched. IPv4 address can be used for a physical interface.
Indicates a NIC of the relay and remote devices.
Indicates an IP set to the NIC of the remote device. This IP address is monitored. IPv4 address can be used for a physical interface.
Indicates a virtual IP of the remote device with which communication should be carried out. IPv4 address can be used for a physical interface.
The ping command is issued periodically to the LAN adapter of the remote system and its response is monitored. If no response is received within a specified period of time, the line is considered to be faulty. Also, if a fault notification (with a special packet) of a line is received from the remote system, the line is considered to be faulty.
Figure 2.21 Monitoring method in GS/SURE linkage mode
The switching time of a line is indicated by [monitoring interval (sec) X monitoring count (count)]. The monitoring interval can be set in the range of 1 to 300 seconds and the monitoring count can be set in the range of 1 to 300 times. By default, they are 5 seconds and 5 times, respectively.
The following failures can be detected:
Figure 2.22 Detectable failures in GS/SURE linkage mode
Monitoring is started automatically when the virtual interface is activated. Monitoring is automatically stopped when the virtual interface is inactivated.
A line whose failure is detected is automatically avoided, and only lines operating normally are used to continue communication.
If a faulty path of a physical interface is recovered, the line of the physical interface is automatically restored for normal communication. The failback of a line cannot be performed manually.
An associated host is able to communicate with the following systems:
When using a GS/SURE communication function:
GS (Global Server)
SURE SYSTEM
ExINCA
When using a TCP relay function:
An optional system (Though a relay device is SURE SYSTEM only).
The requirement for user applications that can be operated in this mode is as follows:
The virtual IP address of Redundant Line Control function is set so that it is fixed as a local IP address using the bind function or others.
Thus, the Internet basic commands of Solaris such as ftp, telnet, and rlogin cannot be used in this mode.
When using a physical interface, it is necessary to assign the IPv4 address.
When using GS/SURE linkage mode (GS/SURE communication capability), the system must be configured as multi-homed host instead of a router.
If you are using Solaris8 or Solaris9 for OS, create an empty file called /etc/notrouter then disable the router and IP forwarding. If you are using Solaris10 for OS, use the "routeadm(1M)" command. See "3.2.2.6 System setup in GS/SURE linkage mode".
RIP, Fast switching and RIP modes are not allowed to coexist in a single node. Additionally, this mode cannot be applied for communication between Solaris servers, and between Solaris servers and Linux servers.
