Hardware Bypass Support

The Bridge mode section describes ho to use nEdge to transparently forward traffic as bump-in-the-wire between two network interfaces, WAN and LAN. In this mode nEdge is able to leverage on a hardware bypass support for implementing automatic failover mechanisms in case of software or other system failures. This is also useful for forwarding the traffic when the system is under maintenance or during a software update.

In bypass mode all packets received from one port are transmitted to the adjacent port. This mode is automatically enabled when nEdge is not running, or in case the software is not working properly for some reason (e.g. the fast path is stuck) by leveraging on a heartbeat mechanism.

nEdge currently supports Silicom bypass adapters only. Please note that no special configuration is required besides installing the Silicom driver: the adapter is automatically detected and the heartbeat mechanism is automatically enabled, as long as the configured WAN and LAN interface belongs to the same bypass segment. Please refer to the following section for the adapter configuration.

The adapter is usually in bypass state when the system is off, and it stays in bypass state until nEdge is up and starts forwarding traffic (at that time the bypass is switched off and the heartbeat mechanism is configured). The hardware bypass is turned on again as soon as nEdge or the whole system is shut down.

Silicom Adapters

In order to enable the bypass support on Silicom adapters, the bp_ctl driver (provided by Silicom) should be compiled and installed. Latest tested version of the driver is is bp_ctl 5.2.0.41.

tar xvzf bp_ctl-xxx.tar.gz
cd bp_ctl-xxx
make && make install

Please note that on some boards like the Silicom RRC-VE CPE, a small patch is required, by adding “#define ADI_RANGELEY_SUPPORT” at the beginning of the bp_mod.c source file.

The bypass driver should be loaded using the bpctl_start tool. Please make sure this is persistent across system reboots: a good practice is to create a pf_ring pre script which is called during the capture framework initialization as shown below.

echo "/bin/bpctl_start" >> /etc/pf_ring/pre
chmod +x /etc/pf_ring/pre
bpctl_start

Please note that a nEdge restart is required after loading the bypass driver in order to make sure that the bypass support is detected and enabled successfully.