How to configure my endpoints to register to a VCS Cluster?

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Updated:April 23, 2015

Document ID:112520

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Introduction

I have a VCS Cluster. How do I configure my endpoints to register to it?

Related Information

Introduction

This article relates to Cisco TelePresence Video Communication Server Expressway.

Q. I have a VCS Cluster. How do I configure my endpoints to register to it?

A. When your VCS is configured as part of a cluster with one or more peers(also known as Alternates), endpoints need to be able to reach theother peers if their primary VCS becomes unavailable. The H.323protocol supports this failover re-registration process automatically,but SIP does not.

The way in which you should configure your endpoints and DNS recordsdepends on the protocol and the functionality supported by yourendpoints.

Initial registration process (SIP and H.323 endpoints)

In order of preference, for providingresilience of connectivity of endpoints to a cluster of VCSs, you arerecommended to use the following registration methods for SIP and H.323endpoints:

DNS SRV records:if the endpoint supports DNS SRV, set up a DNS SRV record for theDNS name of the cluster, giving each cluster peer an equal weightingand priority. The endpoint should be configured with the DNS nameof the cluster. On startup the endpoint issues a DNS SRV request andreceives back the addresses of each cluster peer. It will then tryand register with each peer in turn.

DNS round-robin:if the endpoint does not support DNS SRV, set up a DNSA-record for the DNS name of the cluster and configure it tosupply a round-robin list of IP addresses for each clusterpeer. The endpoint should be configured with the DNS name of thecluster. On startup the endpoint performs a DNS A-record lookupand receives back an address of a peer taken from the round-robin list.The endpoint will try and register with that peer. If that peer is notavailable, the endpoint performs another DNS lookup andthe server will respond with the next peer in the list. Thisis repeated until the endpoint registers with a VCS.

Static IP address:if the cluster does not have a DNS name, configure the endpoint withthe IP address of one of the peers. On startup the endpoint will tryand register with the VCS at that address. If the VCS does not respond,the endpoint will continue trying that same address at regularintervals.

H.323 endpoints: connection failures
Foreach registration method listed above, on registering with the VCS, theVCS responds with anH.323 Alternate Gatekeepers list containing the addresses of VCSclusterpeer members. If the endpoint losesconnection with the VCS it will select another peer from the Alternate Gatekeepers list and try to re-register with that VCS.

SIP endpoints: connection failures

How SIP endpoints behave if they lose connection to their primary VCS depends on their initial registration method:

DNS SRV records: the endpoint uses the DNS SRV entry to find a new VCS to re-register to.

DNS round-robin: the endpoint performs another DNS lookup tofind a new VCS to re-register to (the DNS server providing the next VCS peer in theround-robin sequence).

Static IP address: the endpoint will keep trying to register to that same VCS until it is accessible again.

Formore detailed information about configuring endpoints to work with a VCS cluster,refer to the "Cluster Creation and Maintenance" Deployment Guide (document number D14367).