Znyx Networks bh5700 - Manual (Page 29)

Switch Replacement and Reconfiguration
When a switch fails, it must be replaced. The replacement switch will likely require proper
configuration. For transparent switch replacement, the newly replaced switch must learn its
configuration from its Surviving Partner.
In a simple failover scenario, Host A and Host B are configured with failover between two host
ports, one port connected to Switch A and the other connected to Switch B. Assume Switch A
provides connectivity between Host A and Host B. If Switch A fails, the active link on each host
moves over to the port connected to Switch B. Surviving Partner software on Switch B
recognizes that Switch A has failed, and assumes the role of switching traffic between Host A and
Host B. When the failed Switch A is replaced with a new Switch A', Switch A' will learn its
network configuration from the surviving partner Switch B. Switch A' is now ready as a backup
to Switch B in case of failure of Switch B.
This is achieved through the use of DHCP. When a switch becomes a VRRP Master, a DHCP
server is started with a pointer to a configuration file that contains configuration information for
its partners. The replacement switch comes up running DHCP client to retrieve its configuration.
Proper configuration of Surviving Partner requires coordinated configuration of many different
processes, including vrrpd, zlmd, zlc, and dhcpd. The daemon processes run scripts to
perform their actions. Because these scripts are complex and inter-dependent, a configuration
application called zspconfig is used to build them.
The basic steps to configuring Surviving Partner are:
1. Determine your desired configuration.
2. Modify the configuration file (/etc/rcZ.d/surviving_partner/zsp_DC.conf is
the default) to use as input to the configuration utility (zspconfig).
3. Configure startup scripts or other scripts such as gated routing scripts and vrrp
configuration scripts.
4. Run zspconfig on the Master system.
5. Run zspconfig –u on the Backup/Sibling system(s).
zspconfig
zspconfig performs the job of building the scripts based on a provided input file locally, or
from a remote machine. A text-based configuration file provides input to zspconfig. Example
configuration files are included on the switch in /etc/rcZ.d/surviving_partner. The
result of zspconfig is to create several configuration files and runtime shell scripts, and
optionally start the Surviving Partner processes. Scripts are generated for configuring VLANs,
starting the network, and starting the vrrpd and zlmd daemons.
zspconfig can also used by sibling backup switches to retrieve configuration from the
Surviving Partner and start the vrrpd and zlmd daemons. zspconfig is generally only run
once to configure Surviving Partner.
Ethernet Switch Blade User's Guide release 3.2.2j page 29