Fail-to-Block Mode
This chapter provides information about the fail-to-block mode on SteelHead and SteelFusion appliances and details the hardware and software versions that support fail-to-block mode. It includes the following sections:
This chapter assumes you have installed and configured the appliance.
For SteelHead SD 3070-SD appliances, bypass NICs aren’t required for SteelConnect gateway deployments since LAN traffic requires network address translation (NAT) before it reaches the service provider network. For details on supported SteelHead SD nonbypass NICs, see
SteelHead GX10000.
Overview
This section describes fail-to-block mode as compared to the default fail-to-bypass mode.
Fail-to-bypass mode lets the network maintain connectivity in the event of a failure, without optimization. With fail-to-block mode enabled in a redundant network path environment, traffic is blocked and rerouted to an optimized backup path in the event of a failure.
This feature is useful only if the network has a routing or switching infrastructure that can automatically divert traffic from the link to the optimized backup path. In an active-backup redundant network setup, the active path is configured to use fail-to-block mode, and the backup path is configured to use fail-to-bypass mode, thus traffic continues to be optimized on the backup path if there’s a failure on the active path. In the event of a failure, the LAN and WAN interfaces power down. From a connected router or switch perspective, those devices don’t detect a link.
RiOS supports fail-to-block mode on all cards, including cards that don’t have hardware fail-to-block capabilities, allowing fail-to-block mode functionality with most NICs while the operating system is running.
The following events trigger fail-to-block mode if the feature is enabled:
• Kernel crash
• Hardware failure
• Power loss
SteelHead GX, CX, EX, DX, Interceptor, and SteelFusion NICs and
fail-to-block functionality
All SteelHead GX, CX, DX, EX, Interceptor 9600, and SteelFusion NICs support fail-to-block mode.
SteelHead xx50 NICs and fail-to-block functionality
This table lists the NICs that support the following functionalities in the SteelHead xx50 appliances:
• Blocks on kernel crash
• Blocks on hardware failure
• Blocks on power loss
NIC description | Manufacturing part # |
Two-Port SX Multimode Fiber GbE PCIe card | 410-00101-01 |
Four-Port SX Multimode Fiber GbE PCIe card | 410-00102-01 |
Four-Port Copper GbE PCIe card | 410-00103-01 |
Two-Port LX Single Mode Fiber GbE PCIe card | 410-00105-01 |
Four-Port LX Single Mode Fiber GbE PCIe card | 410-00106-01 |
Two-Port FX Multimode Fiber 100-Mbps PCIe card | 410-00107-01 |
Two-Port LR Single Mode Fiber 10-GbE PCIe card | 410-00301-01 |
Two-Port SR Multimode Fiber 10-GbE PCIe card | 410-00302-01 |
Fail-to-block CLI commands
You can enable the fail-to-block mode on a per interface basis.
Fail-to-block CLI commands:
• no interface <interface-name> fail-to-bypass enable: Sets the interface to block when there’s a failure.
• interface <interface-name> fail-to-bypass enable: Sets the interface to bypass when there’s a failure.
For details on how to test a NIC, see
NIC self-test for SteelHead.