Gatekeeper & CUBE Summary

Why GK & CUBE

Gatekeeper was initially introduced to interconnected several CUCM clusters in a simple and efficient way in large scale IPT network. Call Routing on GK is a 2-matching-steps (Zone Prefix & Technology Prefix) deal. Apart from that, GK also provides supplementary functions such as BW management, Call Admission Control, Name resolution etcs. Besides, GK also provides faster inter-cluster trunk failover than the scenario in which CUCM clusters inter-connected without GK.

CUBE (IPIPGW+SBC) was introduced to replace existing TDM-based (E1/T1) interconnection between Enterprise voice network and PSTN with pure IP-base connection (SIP Trunk). CUBE expands pure IP-based multimedia communication from Enterprise level to Service Provider Level. It also enables pure IP-based interconnection between 2 independent VoIP networks with better interoperatibility, flexibility and compatiblity. How does CUBE achieve that? It is actually done through signaling & medial interworking (terminate & re-orginate), interconnecting VoIP dial peers. Furthermore, as a device in voice network border (SBC: session border controller), it also provides Security features (NAT, NAT Traversal, AAA with RADIUS), QoS and Bandwidth Management.

GK & GW Configuration

GK Config

GK Cluster Guidelines

  1. Up to 5 GKs can be configured in a single GK cluster, in other words, each H323 GW can associated with up to 5 Zones (only 1 active and other 4 standby at any single time) on 5 different GKs for redundancy.
  2. H323 GW is provided with a list of alternate GKs when it registers with the primary GK. However, list of alternate GKs will be lost when GW is powered off or reloaded. Therefore, it is best practice to directly configure the list of alternate GKs on H323 GW.
  3. Up to 100 Zones can be configured on each single GK.

Configure GW to work with GK

interface loopback 0

  h323-gateway voip interface  // determine which interface to source RSA messages, only required

when configuring GW to communication with GK.

  h323-gateway voip id {ZoneOnGKA} {ipaddr ip-address [port] | multicast } [priority priority]

  h323-gateway voip id {ZoneOnGKB} {ipaddr ip-address [port] | multicast } [priority priority]

  h323-gateway voip tech-prefix xxx

  h323-gateway voip h323-id {h323 GW alias }

  h323-gateway bind srcaddr x.x.x.x    // optional, because it can be deleted here and issued under any other active interface as long as this command exist in router configuration. It determines which IP address to source call signaling packet such as H225, H245 etc.

Configure GW to work with GW or CUCM

interface loopback 0

h323-gateway bind srcaddr x.x.x.x

Difference between “h323-gateway voip interface” and “h323-gateway voip bind srcaddr”.

GK Call Flow and Call Routing procedure

GK Call Flow

GK Call Routing

CUBE & GK Interoperation

When interworking with gatekeepers, Cisco UBE can be used in two ways.

  • First, it can register with the gatekeeper, similar to a standard Cisco IOS gateway.
  • Secondly, CUBE and GK can be co-located on the same router as long as CPU ad Memory requirements are met.

In addition, a gatekeeper can use a registered Cisco UBE router with via-zones. This means that when routing a call between two zones, a gatekeeper can be configured to route the call via a zone containing a Cisco UBE router. This enables inter-zone networking using a central Cisco UBE router without the need to deploy a Cisco UBE router at every site or redesign an already-deployed H.323 network.