Cisco Cisco TelePresence Video Communication Server Expressway
The endpoint will continue to use the first VCS that it registered to for re-registrations and for calls. If it ever loses
connection to its VCS, it will use the DNS SRV entry to find a new VCS to register to, starting at the highest priority.
connection to its VCS, it will use the DNS SRV entry to find a new VCS to register to, starting at the highest priority.
DNS SRV cache timeout should be set to a fairly long time (e.g. 24 hours) to minimize DNS traffic.
Option 3 – DNS Round-Robin (3rd choice)
To use this option, there must be a DNS A-record available for the DNS name of the VCS cluster that supplies a
round-robin list of IP addresses.
round-robin list of IP addresses.
On each SIP endpoint configure the SIP Settings as:
■
Server discovery = Manual
■
Server Address = DNS name of the VCS cluster
If the endpoint does not support DNS SRV, on startup the endpoint will perform a DNS A-record lookup. The DNS
server will have been configured to support round-robin DNS, with each of the cluster peer members defined in the
round-robin list.
server will have been configured to support round-robin DNS, with each of the cluster peer members defined in the
round-robin list.
The endpoint will take the address given by the DNS lookup and will then try and register with the relevant cluster
peer. If that is not available, then the endpoint will perform another DNS lookup and will try to connect to the new
VCS peer that it is given. (The DNS server will have supplied the next cluster peer’s IP address.)
peer. If that is not available, then the endpoint will perform another DNS lookup and will try to connect to the new
VCS peer that it is given. (The DNS server will have supplied the next cluster peer’s IP address.)
This will be repeated until the endpoint can register with a VCS.
The endpoint will continue to use the first VCS that it registered to for re-registrations and for calls. If it ever loses
connection to its VCS it will perform another DNS lookup to find a new VCS to register to (the DNS server providing a
VCS in the round-robin sequence).
connection to its VCS it will perform another DNS lookup to find a new VCS to register to (the DNS server providing a
VCS in the round-robin sequence).
DNS cache timeout should be set to a fairly short time (e.g. 1 minute or less) so that if a VCS is not accessible the
endpoint is quickly pointed at a different VCS.
endpoint is quickly pointed at a different VCS.
Option 4 – Static IP (least preferred)
Use this option if the VCS cluster does not have a DNS name.
On each SIP endpoint configure the SIP Settings as:
■
Server discovery = Manual
■
Server Address = IP address of a VCS peer
On startup the endpoint will try and register with the VCS at the specified IP address. If that is not available, then the
endpoint will continue trying at regular intervals.
endpoint will continue trying at regular intervals.
This will be repeated until the endpoint can register with the VCS.
The endpoint will continue to use the first VCS that it registered to for re-registrations and for calls. If it ever loses
connection then it will keep on trying to register to that VCS until it is accessible again.
connection then it will keep on trying to register to that VCS until it is accessible again.
H.323 Endpoints
The options below are listed in preference order for providing resilience of connectivity of endpoints to a cluster of
VCSs where 1 or more VCS cluster peers become inaccessible. The choice of option will depend on what
functionality the endpoint you are using supports.
VCSs where 1 or more VCS cluster peers become inaccessible. The choice of option will depend on what
functionality the endpoint you are using supports.
Option 1 – DNS SRV (preferred)
To use this option, there must be a DNS SRV record available for the DNS name of the VCS cluster that defines an
equal weighting and priority for each cluster peer.
equal weighting and priority for each cluster peer.
On each H.323 endpoint, configure the Gatekeeper Settings as:
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Cisco TelePresence VCS Cluster Creation and Maintenance Deployment Guide
Appendix 7: Configure Endpoints to Work With a Cluster