|C H A P T E R 5|
This chapter describes network ports and alias IP addresses on the NAS server. You can bond two or more ports together to create a port bond. A port bond has higher bandwidth than the component ports assigned to it.
About Port Locations and Roles
NAS appliances and gateway systems identify ports based on their type, and their physical and logical location on the server. To identify the port locations for your system, refer to the Getting Started Guide for your NAS appliance or gateway system.
In cluster configurations, the primary port plays an integral part in the failover process. When you assign this role to a port, the partner server in the cluster saves a copy of the IP address of that port as an inactive alias IP address. In addition, when you configure alias IP address on either server, the partner server holds those IP address as additional inactive alias IP addresses. If a failover occurs, the healthy server activates the inactive alias IP addresses corresponding to the IP addresses for the failed server, allowing network access to continue as if the failed server were still active.
In a cluster configuration, the independent port does not participate in the failover process. You cannot bond (aggregate) independent ports or add alias IP addresses to them. You can assign any number of independent port roles, but assign only one per server.
About Alias IP Addresses
Internet protocol (IP) aliasing is a networking feature that lets you assign multiple IP addresses to a single port. Typically, aliases specify the IP addresses of obsolete systems that have been replaced by NAS storage.
For single-server appliances and gateway systems, you can add up to nine alias IP addresses to the primary IP address of each port. Therefore, a single network interface card (NIC) with two ports can provide up to 20 usable IP addresses.
On cluster appliances and gateway systems, you can only add alias IP addresses to ports that are assigned a primary role. (See About Port Locations and Roles for a description of port role options.) To ensure a successful failover in the event that one server fails, you must split the alias IP addresses evenly between the servers, assigning no more than four alias IP addresses to the primary port on each server. The other five slots are reserved for use during failover, when the server that remains operational will take over the IP address and (up to four) alias IP addresses from the failed server. This allows network access to continue with minimal interruption. See Enabling Server Failover for details on head failover.
Note: Do not confuse the primary role with the primary IP address. The primary role is an assignment indicating how the port functions in a cluster configuration. The primary IP address is the first address assigned to a selected port. In Web Administrator, the primary IP address is shown on the Network Configuration > Configure TCP/IP > Configure Network Adapters panel. You can select the port role at the bottom of the screen.
There are two types of port bonding: port aggregation and high availability. Port aggregation bonding combines two or more adjacent ports to created a faster port, a port of greater bandwidth. High availability bonding combines two or more ports to provide network interface card (NIC) port failover services or back-up ports.
NAS appliances and gateway systems support Etherchannel bonding, a subset of the 802.3ad specification. Refer to your switch documentation for Etherchannel bonding before attempting to set up port bonding.
Port aggregation bonding (otherwise known as "channel bonding, aggregating, or trunking) lets you scale network I/O by joining adjacent ports. This forms a single network channel of high bandwidth from two or more channels of lower bandwidth.
An aggregation bond requires a minimum of two available ports. The ports also must be of the same interface type (for example, Fast Ethernet with Fast Ethernet), connect to the same subnet, and must connect to adjacent ports on the same network switch.
High-availability (HA) port bonding provides port failover capabilities to the system. Two or more available ports are bonded so that if the primary port fails, a secondary port in the high-availability bond takes over the burden to enable services to continue without any interruptions. As with port aggregation bonding, this type of bonding does not increase bandwidth.
You can bond ports after configuring them. However, alias Internet Protocol (IP) addresses and some other aspects of the original configurations might change. After you create a port bond, see About Configuring Network Ports to configure the port bond. After you bond two or more ports, you cannot add IP aliases to the individual ports, only to the bond.
If you chose Port Aggregation in Step 3, you must select ports that have the same type of interface and are connected to adjacent ports.
To add alias IP addresses to the port bond, see Configuring Network Adapters.
To bond ports on dual-server systems, you only need to complete the following procedure on one server. All ports in a port bond must be the same type (for example, Fast Ethernet with Fast Ethernet), connect to the same subnet, and connect to adjacent ports on the same network switch. The system reboots immediately after each port bonding.
You can bond ports after configuring them. However, alias Internet Protocol (IP) addresses and some other aspects of the original configurations might change. After you create a port bond, see About Configuring Network Ports to configure the port bond.
For more information on dual-server port bonding, see Example: Dual-Server Port Bonding.
Note: You can use only ports with a Primary role for port bonding. For more information about port roles, see About Port Locations and Roles.
On the partner server, the corresponding ports are automatically bonded as well, after you click Apply and the server reboots. For example, if you bond Ports 2 and 3 on Server H1, Ports 2 and 3 on Server H2 are also bonded.
6. To add alias IP addresses to the port bond, see Configuring Network Adapters.
FIGURE 5-1 shows an example of a cluster appliance connected to two different subnets. To show all possible combinations, this example represents each server as having a heartbeat port and four additional ports. All ports except the heartbeat port on each server are configured with a Primary role.
TABLE 5-1 lists the Internet protocol (IP) when Ports 2 and 3 are bonded, and Ports 4 and 5 are bonded
In the event of head failover, the surviving server activates the IP addresses of the failed server. You can add alias IP addresses to the primary IP address of a port bond and those IP addresses participate in the failover process. For more information about IP aliases, see About Alias IP Addresses.