HP VAN SDN Controller Administrator Guide v3

only. This component depends on other network service components like
Node Manager and Topology.
Path Daemon does the following:
• It registers with the controller as a "DIRECTOR". Only Directors are
allowed to send a packet out.
• It registers for only ARP packets and IPv4 Packets.
• The flowchart below explains the Path Daemon algorithm.
• Uses the Node Service to get the end hosts corresponding to the source
and destination MAC addresses and the switches to which these hosts
are connected. It makes use of the Topology Service to get the
end-to-end path between the source and destination switches. It makes
use of the controller to push flows to the switches. The flowchart in
Figure 13 provides more details of its operation.
• Path Daemon uses the following match fields when pushing a flow
module. These match fields have been chosen so that the flow modules
are pushed on hardware tables in both Provision and Comware
switches.
◦ Ether Type
◦ Source Macaddress
◦ Destination Macaddress
◦ Input Port
◦ Output port
Path Daemon also registers for PORT STATUS DOWN messages. When
such messages are received, Path Daemon removes all flows configured
for the impacted port, thereby causing the packet-ins to again come to the
controller.
Operation notes:
• Does not handle multicast and broadcast traffic
• Does not configure the reverse path along with the forward path
• Drops packets from sources that the controller has not learned
• Floods packets when their destinations are not known
• Does not support multi-pathing or fast-failover
• Performance is topology-dependent, recommended for 100-200 node
environments
The Path Daemon application uses the Topology Service, Node Service,
and Flow Service applications. For more on Path Daemon, see Figure 13.
Determines and verifies the path taken by a specific packet from a source
host to destination host.
Path Diagnostics
• Evaluates flows configured across the switches in the control domain
for diagnosis.
• Creates ‘Observation posts’ on every switch in the path that the packet
would take.
• Tallys packet_ins from the observation posts to figure out where a path
is broken.
• Lists neighbors for any given device.
Builds information about links between network elements in the controller
domain. Provides information about the linkages between network elements
Link Manager
and serves as a base for other applications such as topology, etc. This
application maintains a table of source and destination devices and ports,
and transmits LLDP PDUs to all detected devices.
20 SDN Controller Console