Cisco Cisco TelePresence Video Communication Server Expressway
Appendix 5 – Configuring endpoints to work with a VCS cluster
Cisco VCS Deployment Guide: Cluster creation and maintenance (Cisco VCS X7.1)
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Server discovery = Manual
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Server Address =
DNS name of the VCS cluster (if DNSSRV name is available) or
DNS name of a different cluster peer or
IP address of a different cluster peer
Outbound = On
Option 2 – DNS SRV (2
nd
choice)
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.
that defines an equal weighting and priority for each cluster peer.
On each SIP endpoint configure the SIP Settings as:
Server discovery = Manual
Server Address = DNS name of the VCS cluster
If the endpoint supports DNS SRV, on startup the endpoint issues a DNS SRV request and receives a
DNS SRV record back defining an equal weighting and priority for each cluster peer. It may also
receive a list of lower priority entries pointing at a fallback cluster.
DNS SRV record back defining an equal weighting and priority for each cluster peer. It may also
receive a list of lower priority entries pointing at a fallback cluster.
The endpoint then tries to register with a relevant cluster peer (having taken into account the priority /
weightings). If that peer is not available, the endpoint will try and register to another listed peer at the
same priority, or if all peers at that priority have been tried, a peer at the next lower priority.
weightings). If that peer is not available, the endpoint will try and register to another listed peer at the
same priority, or if all peers at that priority have been tried, a peer at the next lower priority.
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 use the DNS SRV entry to find a new VCS to register to,
starting at the highest priority.
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.
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 (3
rd
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.
supplies a 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.
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.
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.)
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.)
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).
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).
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.
accessible the endpoint is quickly pointed at a different VCS.