Hi, my company operates in several countries and we are designing IP Telephony and VoIP to leverage our global WAN usage and slowing adopting IPT. Right now we are on two locations in Sao Paulo, one of them on what we call Full IPT site (7911 and 41 phones, some IP Comm and a 2851 with two E1 to PSTN) and the older one using traditional PBX linked to two 2851 for redundant connection to PSTN and Alcatel PBX. We intend to expand this model across to 8 more sites in Brazil, two using full IP telephony and the others having the voice gateway intermediating call between PBX and PSTN, also handling on net calls in the global WAN for intracluster calls. Voice gateways are MGCP controlled (because of FAX issues on using ISDN) with H.323 fallback and SRST.
The project also includes a new cluster in Buenos Aires controlling this site and some other sites in southern South America and another cluster in Santiago for 6 cities in Chile and some others in andian countries.
I am not quite sure on how to deploy CAC between sites in different clusters. Locations cannot be used between clusters, if I'm not wrong. Also gatekeeper would be able handle CAC between H.225/GK controlled clusters (we intend to have all 3 clusters trunking with 2 GKs). But since the how global network is MPLS and each site has direct connection to the others, the gatekeeper wouldn't be able to know to each site in a cluster the bandwidth is allocated.
It looks like RSVP can be used to control admission between all sites because they can be used in intercluster trunks. Since we cannot control MPLS edge gateways as they are managed by the SP (other than telling them to provide a specific LLQ bandwidth), we would be using the voice gateways with two gigabit ethernet interfaces between SP routers and LAN swiches (aggregating a few more network addresses in this task) since SP routers can't do RSVP.
Have someone tried a setup on a network like that? Would that be a bad design (considering we could not deploy just one cluster across whole South America since some sites have more than 720 people and to have more redundancy) or any big caveats? I would assume that by using RSVP in CUCM6.x for that there would be no need of using locations for CAC or could it be using integrated with RSVP?
I'd be glad to hear comments and ideas. Regards.
For the ICT trunks between the clusters you would have to have IP-IP GWs if you wanted to use RSVP. It will not work with just GKPs but of course if your using just gkps couldnt you put each cluster into a zone then restrict the bandwidth to each one?? I guess you would also need a star topology for that though.
Cant you enable the rsvp on the voice gateway before it hits the SP edge? If RSVP is not enabled on a device it becomes transparent to the RSVP so it will work even though the SP doesnt support it.
If you going to use RSVP best to use it in intser/diffserv mode as this allows you to apply your own Qos and queuing appose to RSVP doing it all.
I have done a similar setup with 4 clusters using Gatekeepers with IPIPGws which are running RSVP. One cluster had 19 remote sites running FR and MPLS all RSVP enabled. I didnt have any problems other than playing around with how much bandwith to allocated to each interface.
If you need any RSVP configs or any help with that let me know.
hope some of that helps