Znyx Networks bh5700 - Manual (Page 27)

Chapter 3 High Availability Networking
High availability networking is achieved by eliminating any single point of failure through
redundant connectivity: Redundant cables, switches and network interfaces for hardware,
combined with HA software solutions on both the hosts and switches to control the HA hardware
and maintain connectivity. An HA solution called Surviving Partner is provided on the switch.
For host-side HA, the most common solution is to use the Linux bonding driver. HA solutions
like the Linux bonding driver present a single, virtual interface to the protocol stack while
managing multiple physical links. Figure 3.1: Host HA Architecture shows the relation of the
protocol stack, a bonding driver and physical ports.
A failover between physical links can be made very quickly without requiring change to the IP or
MAC address of the virtual interface, effectively transparent from the applications point of view.
With redundant links from a switch (or switches) to the host, one link is maintained as the
ACTIVE link and the other as STANDBY. If the ACTIVE link were to go down, the STANDBY
becomes the new ACTIVE, while presenting the same virtual interface to the host.
NOTE: It is important that the bonding solution provide an active-backup mode. For the
Linux bonding driver set “mode == 1” see the http://sourceforge.net/projects/bonding/
documentation for more information. Use the recommendations for Linux kernel 2.4x not
2.6x.
Redundant connections provide an ACTIVE and STANDBY link to a switch, or provide
redundant links between more than one switch. In the case of more than one switch, a complete
HA solution requires a switch-based HA solution.
Surviving Partner
Surviving Partner is a switch-based HA solution. Surviving Partner runs on the switches to
provide transition of Layer 2 and Layer 3 switching functionality between two or more switches.
Surviving Partner is comprised of many interactive protocols and processes including VRRP,
zlmd, zlc, and others.
Ethernet Switch Blade User's Guide release 3.2.2j page 27
Figure 3.1: Host HA
Architecture