Cisco Cisco TelePresence Video Communication Server Expressway
Appendix 6 – Configuring endpoints to work with a Cisco VCS cluster
and will try to connect to the new Cisco VCS peer that it is given. (The DNS server will have supplied
the next cluster peer’s IP address.)
the next cluster peer’s IP address.)
This will be repeated until the endpoint can register with a Cisco VCS. On registering with the Cisco
VCS, the Cisco VCS will respond with the H.323 ‘Alternate Gatekeepers’ list containing the list of
Cisco VCS Cluster peer members.
VCS, the Cisco VCS will respond with the H.323 ‘Alternate Gatekeepers’ list containing the list of
Cisco VCS Cluster peer members.
The endpoint will continue to use the first Cisco VCS that it registered to for re-registrations and for
calls. If it ever loses connection then it will select an “Alternate Gatekeeper” from the list it was
supplied with.
calls. If it ever loses connection then it will select an “Alternate Gatekeeper” from the list it was
supplied with.
DNS cache timeout should be set to a fairly short time (e.g. 1 minute or less) so that on failure to
reach a Cisco VCS at startup, the endpoint is quickly pointed at a different Cisco VCS.
reach a Cisco VCS at startup, the endpoint is quickly pointed at a different Cisco VCS.
Option 3 – Static IP (least preferred)
Use this option if the Cisco VCS cluster does not have a DNS name.
On each H.323 endpoint configure the Gatekeeper Settings as:
Discovery = Manual
IP Address = IP address of a Cisco VCS peer
On startup the endpoint will try and register with the Cisco VCS at the specified IP address. If that is
not available, then the endpoint will continue trying at regular intervals.
not available, then the endpoint will continue trying at regular intervals.
This will be repeated until the endpoint can register with the Cisco VCS. On registering with the Cisco
VCS, the Cisco VCS will respond with the H.323 “Alternate Gatekeepers” list containing the list of
Cisco VCS Cluster peer members.
VCS, the Cisco VCS will respond with the H.323 “Alternate Gatekeepers” list containing the list of
Cisco VCS Cluster peer members.
The endpoint will continue to use the first Cisco VCS that it registered to for re-registrations and for
calls. If it ever loses connection then it will select an “Alternate Gatekeeper” from the list it was
supplied with.
calls. If it ever loses connection then it will select an “Alternate Gatekeeper” from the list it was
supplied with.
SIP endpoints
The options below are listed in preference order for providing resilience of connectivity of endpoints to
a cluster of Cisco VCSs where 1 or more Cisco VCS cluster peers become inaccessible. The choice
of option will depend on what functionality the endpoint you are using supports.
a cluster of Cisco VCSs where 1 or more Cisco 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 Cisco VCS
cluster that defines an equal weighting and priority for each cluster peer.
cluster 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 Cisco 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 Cisco VCS.
The endpoint will continue to use the first Cisco VCS that it registered to for re-registrations and for
calls. If it ever loses connection to its Cisco VCS, it will use the DNS SRV entry to find a new Cisco
VCS to register to, starting at the highest priority.
calls. If it ever loses connection to its Cisco VCS, it will use the DNS SRV entry to find a new Cisco
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.
Cisco VCS Deployment Guide: Cluster creation and maintenance (Cisco VCS X5)
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