PCoIP Management Console User Manual
Algorithm
Each time a PCoIP device boots it executes the MC DNS-Based Discovery algorithm if
the
PCoIP MC DNS-Based Discovery Prefix
setting is non-blank. The algorithm uses the
setting and the domain name hierarchy to search for a MC.
The PCoIP device obtains the domain name string from the DHCP server using DHCP
options 15. Since some DHCP servers may not have DHCP options 15 implemented, the
device also obtains the host name using DHCP options 12 (assumed to include the
domain name).
Since the device and MC may not be on the same domain (but must be within the same
hierarchy), the device composes many FQDN variations using the results from DHCP
options 12 and 15. With each FQDN variation, the hostname prefix remains constant
however the domain hierarchy level changes.
The device sequentially attempts each FQDN possibility until a hit is found, at which point
the device completes DNS-based discovery. The algorithm may take several minutes in
order to find the correct FQDN address of the MC (depends on the number of levels in
the domain name hierarchy and the MC load).
In detail, the algorithm works as follows. The device uses domain name variations based
on the DHCP options 15 string. For each FQDN possibility, the device attempts to
transmit a status message to the MC at the FQDN. Upon transmission timeout, the
device composes the next FQDN variation by proceeding one level up the domain
hierarchy. The last domain name attempted has a single dot in the string. After
exhausting the FQDN possibilities (based on the DHCP options 15 string), the device
delays for 5 minutes and then uses hostname variations based on the DHCP options 12
string. After failing to contact a MC using the DHCP options 12 string, the device delays 5
minutes and then cycles back to using DHCP options 15. The device continues this
process until a MC is contacted.
Example
In the example below, the DHCP options 15 returns sales.europe.companyname.com.
DHCP options 12 returns hostmachine1.sales.europe.companyname.com. Note that the
DHCP server may return no value for either option. The MC configured the PCoIP MC
DNS-Based Discovery Prefix in the device to equal pcoip_mc1.
The device creates the following FQDNs and sequentially attempts contact with the MC:
(attempt #1) pcoip_mc1.sales.europe.companyname.com
(attempt #2) pcoip_mc1.europe.companyname.com
(attempt #3) pcoip_mc1.companyname.com
<device delays for 5 minutes>
(attempt #4) pcoip_mc1.hostmachine1.sales.europe.companyname.com
(attempt #5) pcoip_mc1.sales.europe.companyname.com
(attempt #6) pcoip_mc1.europe.companyname.com
(attempt #7) pcoip_mc1.companyname.com
<device delays for 5 minutes>
(attempt #8) pcoip_mc1.sales.europe.companyname.com (repeat 1-7)
TER0812002 Issue 5
19
