Cisco Cisco TelePresence Video Communication Server Expressway
Appendix 6 – Configuring endpoints to work with a Cisco VCS cluster
Cisco VCS Deployment Guide: Cluster creation and maintenance (Cisco VCS X6)
Page 56 of 76
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 peer is not available, then the endpoint will perform another DNS lookup
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.)
relevant cluster peer. If that peer is not available, then the endpoint will perform another DNS lookup
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.)
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 VCS at the specified IP address. If that is not
available, then the endpoint will continue trying at regular intervals.
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 – SIP Outbound (preferred)
SIP outbound allows an endpoint to be configured to register to 2 or more Cisco VCS peers
simultaneously. The benefit of this is that if the connection between one Cisco VCS peer and the
endpoint gets broken, then a connection from the endpoint to the other peer remains. With the
endpoint registering to both simultaneously, there is no break in service whilst the endpoint realizes
that it’s registration has failed, before it registers to a different peer. Thus, at no time is the endpoint
unreachable.
simultaneously. The benefit of this is that if the connection between one Cisco VCS peer and the
endpoint gets broken, then a connection from the endpoint to the other peer remains. With the
endpoint registering to both simultaneously, there is no break in service whilst the endpoint realizes
that it’s registration has failed, before it registers to a different peer. Thus, at no time is the endpoint
unreachable.
Configuration of SIP outbound is endpoint specific, but typically will be:
Proxy 1
•
Server discovery = Manual
•
Server Address =
DNS name of the Cisco VCS cluster (if DNSSRV name is available) or