User guide

Configuring Automatic Fabric Automatic Fabric Discovery Examples
OmniSwitch AOS Release 7 Switch Management Guide March 2015 page 14-19
Automatic Fabric Process for Automatic IP Configuration
When an IP interface is automatically configured for OSPF or IS-IS routing, the interface initially operates
in passive mode. This means that the interface listens for Hello PDUs from neighbor switches to detect
and configure OSPF neighbors or IS-IS adjacencies. The interface does not initially transmit Hello PDUs.
Automatic OSPF Configuration
OSPF neighbors are detected through Hello packets received from neighbor switches. From these packets,
the Area ID, Hello interval, and Dead interval values are learned and used to configure the OSPF
interface. Both OSPFv2 and OSPFv3 learn areas and neighbors in a similar way.
The following scenarios are general examples of the automatic IP configuration process for the OSPF
protocol.
Two Automatic Configuration Routers
• Both routers listen for Hello packets.
• Since neither router sends Hello packets in this scenario, no neighbors are learned.
One Configured Router and One Automatic Configuration Router
• The configured router sends the default Hello packets.
• The automatic configuration router receives the Hello packets and sends Hello packets with the learned
information.
• The configured router receives Hello packets from the automatic configuration router and both routers
become neighbors.
• The interface and area information is synchronized on the automatic configuration router.
Automatic IS-IS Configuration
The IS-IS automatic configuration process is similar to the OSPF process in that adjacencies are learned
from Hello packets received from neighbor switches. In addition, the following items apply specifically to
the building of IS-IS adjacencies:
• An Area ID of 0.0.0.0 is used to help learn L2 adjacencies.
• Areas and level (L1, L2, L1L2) are learned from the received Hellos.
• The Hello time, Hello interval, and multiplier values are not learned from the received Hello packets.
Instead, the automatic configuration process uses the default IS-IS holding time (27 seconds for non-
DIS and 9 seconds for DIS) to derive the needed values.
Both IS-IS IPv4 and IS-IS IPv6 learn areas and neighbors in a similar way.
The following scenarios are general examples of the automatic IP configuration process for the OSPF
protocol.
Two Automatic Configuration Routers
• Both routers listen for IS-IS Hello packets.
• Since neither router sends IS-IS Hello packets in this scenario, no neighbors are learned.