IRF FAQ

Q.     What benefits can IRF provide?

A.     IRF provides the following benefits:

·     Simplified management—An IRF fabric appears as one node and is accessible at any port on any member device for management of all the IRF member devices.

·     1:N redundancy—In an IRF fabric, one member acts as the master to manage and control the entire IRF fabric. All the other members process services while backing up the master. When the master fails, the other member devices elect a new master from among them to take over without interrupting services.

·     Multichassis link aggregation—You can aggregate the physical links between the IRF fabric and its upstream or downstream devices across the IRF members for redundancy and load balancing. When a member device fails, packets can be forwarded over the links on the remaining IRF member devices.

·     Network scalability and resiliency—Processing capacity of an IRF fabric equals the total processing capacities of all the members. You can increase ports, network bandwidth, and processing capacity of an IRF fabric simply by adding member devices without changing the network topology.

Q.     What are the hardware and software requirements for setting up an IRF fabric?

A.     The following are the hardware and software requirements for setting up an IRF fabric:

·     All IRF member devices must run the same software image version. Make sure the software auto-update feature is enabled on all member devices. This feature automatically synchronizes the current software images of the master to devices that are attempting to join the IRF fabric.

·     For a license-based feature to run correctly on an IRF fabric, make sure the licenses installed for the feature on all member devices are the same.

·     Ports that can be used as IRF physical interfaces vary by device model. Typically, use high-speed ports as IRF physical interfaces.

·     Use the following guidelines when you select and connect IRF physical interfaces:

¡     If you use fiber Ethernet ports to establish IRF links, use transceiver modules and fibers to connect fiber Ethernet ports. This option is suitable for long-distance transmission and increases flexibility in networking.

¡     If you use copper Ethernet ports to establish IRF links, use copper Ethernet cables to connect them. This option is suitable for short-distance transmission.

Q.     What should I pay attention to when I upgrade an IRF fabric?

A.     To ensure a successful upgrade of an IRF fabric, save the target software image file on each member device in the IRF fabric. Alternatively, choose to do an overwrite upgrade when you are prompted for an upgrade method confirmation during upgrade.

To avoid upgrade downtime, perform ISSU upgrade as long as possible.

Q.     Are there any restrictions on configuring session dual-active mode on an IRF fabric?

A.     Yes. Use the following restrictions and guidelines when you place the IRF fabric in session dual-active mode:

·     If you connect the IRF fabric to two upstream switches and two downstream switches through Ethernet interfaces in bridge mode, make sure the upstream and downstream switches support multichassis link aggregation.

·     You must enable session dual-active mode by using the session dual-active enable command. In addition, do not change the mode when service traffic is present.

·     If hash-based session creation is used, transparent transmission for UDP packets does not take effect. The devices do not relay UDP packets.

·     Session dual-active mode is not available on the F50X0-D series, F5000-AK series, and modules for installation in other devices.

·     The service interfaces can operate in route (Layer 3) or bridge (Layer 2) mode. However, you must place the service interfaces in route mode in an RBM+VRRP deployment, because VRRP is a Layer 3 protocol.

·     Per-packet load balancing is not supported in a dual-active environment.

·     If you use NAT easy IP on an M9000 device, NAT port halving (with the nat port-load-balance enable command) takes effect only when the system operates in active-standby mode. As a best practice, do not enable NAT port halving in dual-active mode.

·     Address family translation (AFT) is not supported in dual-active mode.