by Olivier | Mar 4, 2010 | H.323, IOS, Lab, Non classé, Written Theory
Here are the different messages used by the H225 RAS signaling which can occur between endpoints and GK.
- Gatekeeper Discovery : used by endpoints to register
- GRQ : Gatekeeper Request
- GCF : Gatekeeper Confirm
- GRJ: Gatekeeper Reject
- Registration/Unregistration : used by endpoints to register or unregister their address and their zone withtin the GK.
- RRQ : Registration Request
- RCF : Registration Confirm
- RRJ : Registration Reject
- URQ : Unregistration Request
- UCF : Unregistration Confirm
- URJ : Unregistration Reject
- Admission Control : These messages are used for all admission control and bandwidth management
- ARQ : Admission Request
- ACF : Admission Confirm
- ARJ : Admission Reject
- Bandwidth Control : these messages are used if you want to change the amount of bandwidth during a call
- BRQ : Bandwidth Request
- BCF : Bandwidth Confirm
- BRJ : Bandwidth Reject
- Endpoint Location : These messages are used to retrieve contact information ( also with Directory GK)
- LRQ : Location Request
- LCF : Location Confirm
- LRJ : Location Reject
- Status Information : They are used to retrieve a status information
- IRQ : Information Request
- IRR : Information Response Request
H225 call control signaling is on TCP/1720 and uses Q931 messages to establish, maintain and tear down calls. these messages are
- Setup
- Setup Acknowledge
- Call Proceeding
- Progress Alerting
- Connect
- User Information
- Release Complete
- Status Inquiry
- Status
- Information
- Notify
So in general , here is the following reminder: While h225 call control signaling can be used for call setup, H245 must be used to determine a master/slave relationship, exchange terminal capabilities, logical channel signaling and DTMF relay.
by Olivier | Mar 4, 2010 | H.323, IOS, Lab, Non classé, Written Theory
We have already spoken about Gatekeeper signaling in this previous post but let’ be more general and see what are the common elements of H.323 stack.
We have H225 RAS ( Registration Admission and Status) which is used between the GK and H323 endpoints.
But under normal operation , we have also H225 which is the call control and signaling part of the H323 stack. So we use it to establish connections.
We have also H245 which is the negotiation part of the H323 stack. So it is during this stage that you can exchange capabilities/codecs, establish logical channels. It is in fact all settings for the transmission of the media.
Reminder:
- H225 RAS => UDP/1719
- GK Discovery => UDP/1718
The Multicast GK discovery uses IP Address 224.0.1.41
by Olivier | Mar 2, 2010 | CUCM, H.323, Non classé, SIP, Written Theory
A MTP can bridge tohether two full-duplex voice stram and if necessary convert between G711 ulaw and alaw as well as different sample sizes. So as the MTP bridge is handling each stream independently, H.323 supplementary services can be supported. In other words, MTP will enhance H.323v1 with all these supplementary services(Call Park, Hold , Transfer , Conferencing,…).
Pay attention also that you can use MTP in order to provide the translation between the out-of-band DTMF tones used by SCCP and SIP in-band (payload type) DTMF tones.
by Olivier | Mar 2, 2010 | CUCM, H.323, IOS, Non classé, Written Theory
Digit Manipulation is the process of modifying the called or calling party number. It can be configured in a number of different ways:
- Route Pattern
- Route Group Level
- Translation Pattern
- Translation Rules in VGW
The specific types of manipulatios are :
- Calling Party’s Extenal Phone Mask
- Calling Party Transform Mask
- Prefix Digits
- Discard Digits Instructions(DDI)
- Called Party Transform Mask
Although Digit Manipulation canbe done within a Route Group, it is applied when the the Route Groups are added to the Route List.
Recall also as seen in a previous post, that when digit manipulations are configured at both the Route Pattern and Route Group level, the manipulation configured at the Route Group level has priority over that configured at the Route Pattern level because it is processed later.
Translation patterns can be used also to manipulate the calling or called party numbers prior to call routing. It can be also used to modify elements such as CSS.
by Olivier | Mar 2, 2010 | H.323, IOS, Lab, Non classé, Written Theory
Here is a basic definition for the gatekeeper config:
!
gatekeeper
zone local oks ksiazek.be 10.0.0.1 1719
zone prefix oks 1234*
gw-type-prefix 1#* default-technology
bandwidth total zone oks 1024
bandwidth session zone oks 128
no shutdown
!
The zone local defines the Gatekeeper’s name , the domain to which it belongs and its IP Address and the TCP port used.
The zone prefix specifies the Gatekeeper’s name and the prefix associated within the zone list.
The gw-type-prefix will help to route calls if the called number doesn’t correspond to an E.164 number.
The bandwidth total zone defines the maximum aggregate bandwidth that you can use within this specific zone.
The bandwidth session zone defines the maximum bandwidth available for a session in the zone ( so this is the bandwidth for a call)
No shut activates the Gatekeeper’ configuration.
by Olivier | Feb 25, 2010 | H.323, IOS, Lab, Non classé, Written Theory
Endpoints which are using multicast discovery will use the multicast adress 224.0.1.41 for GRQ
