When enabling the presence service in CUCME, you are using the SIP methods of Subscribe and Notify to allow users the ability to see changes in the line state of phones.  The phone acts as a watcher using the subscribe method to get status updates from a directory number assigned to a phone that acts as the presentity.  CUCME will respond to the request and each time there is a status update for that DN or presentity, CUCME will send all watchers a notification message.  CUCME presence can be applied either as a BLF speed-dial assigned to a line button or as BLF call-lists that will support status notifications of a presentity in the directories or call log (missed, placed, received) of the phone.

The first step when configuring presence on CUCME is to enable the router the ability to accept incoming presence requests.

BR2-RTR(config)#sip-ua

BR2-RTR(config-sip-ua)# presence enable

The next step is to enable the presence service and the ability to globally monitor all directory number that will need to be enabled for “watching” via the call lists and directories of the local phones.

BR2-RTR(config)#presence

BR2-RTR(config-presence)#presence call-list

Then configure the directory numbers that will be enabled for watching.

SCCP Phones

BR2-RTR(config)#ephone-dn 1

BR2-RTR(config-ephone-dn)#allow watch

SIP Phones

BR2-RTR(config)#voice register dn 1

BR2-RTR(config-register-dn)#allow watch

!

BR2-RTR(config)#voice register global

BR2-RTR(config-register-global)#create profile

BR2-RTR(config-register-global)#reset

At this point, if BLF monitoring of directory numbers that appear in the call lists and the directories has not been enabled globally, then this can be applied at the phone level and reset devices.

SCCP Phones

BR2-RTR(config)#ephone 1

BR2-RTR(config-ephone)#allow watch

!

BR2-RTR(config)#telephony-service

BR2-RTR(config-telephony)#create cnf

Creating CNF files

BR2-RTR(config-telephony)#reset all

SIP Phones

BR2-RTR(config)#voice register pool 1

BR2-RTR(config-register-pool)#allow watch

!

BR2-RTR(config)#voice register global

BR2-RTR(config-register-global)#create profile

BR2-RTR(config-register-global)#reset

In the event it was asked to enable BLF monitoring of a directory number and associate this DN with a speed-dial assigned to a line button on the phone then first ensure the DN has “allow watch” assigned and then perform the following.

SCCP Phones

BR2-RTR(config-ephone)#blf-speed-dial 1 3001 label Sales

BR2-RTR(config-ephone)#reset

SIP Phones

BR2-RTR(config)#voice register pool 1

BR2-RTR(config-register-pool)#blf-speed-dial 1 3001 label Sales

!

BR2-RTR(config)#voice register global

BR2-RTR(config-register-global)#create profile

BR2-RTR(config-register-global)#reset

By assigning a BLF speed-dial to a phone, it enables that phone to watch all ephone-dns or voice register dns with that same extension number at the same time acting as a speed-dial.  However, with CUCME version 7.0 the lamp will only illuminate red if the monitored dn is in use.  It will not indicate DND status and cannot distinguish which phone is using the extension number if it is shared across multiple phones or assigned to multiple DNs, much like that of the “monitor mode” button “m”.  The main difference to remember with Monitor Mode button is that it is only supported on SCCP devices and will only monitor a single ephone-dn <tag>.  It is not extension number based.  In CUCME 7.0 to achieve status updates if a phone is in DND mode, it can be achieved with the “watch mode” button “w”. This method of presence will watch all activity on the phone in which the ephone-dn  <tag> assigned is the primary extension.  It should be noted here that the ephone-dn used in this method could be shared across phones but not assigned as the primary extension to more than one phone.

To verify presence use the following commands.

-show presence global

-show presence subscription

To troubleshoot presence use the following commands.

-debug presence X

-debug ephone blf <mac-address>

-debug ccsip messages

Amy Ryan – CCIE #24677 (Voice)
Technical Instructor – IPexpert, Inc.
Mailto: aryan@ipexpert.com

In CUCME 4.1 and later versions, it is possible to provide end users the flexibility of creating ad-hoc conferences involving more than 3 parties with each participant potentially using a low bit rate codec such as g729. As you might expect, IOS software is unable to provide this function natively without the aid of Digital Signal Processors (DSP’s) most likely hosted on the CUCME gateway.

The first step when configuring the DSP’s for conferencing is to enable DSPFarm services on the gateway. By default the DSP’s can only be utilized for voice termination.

BR1-RTR(config)#voice-card 0
BR1-RTR(config-voicecard)#dsp service dspfarm

The DSP resources can only be controlled by the Call Control Agent (UCME in this case) using Skinny (aka SCCP). Skinny needs to be enabled on the gateway and a Call Control Agent(s) defined. In the example below the gateway will source SCCP packets from the primary IP Address assigned to interface FastEthernet0/0.11. The CUCUM IP Address is then provided to the gateway- incidentally the default version of SCCP used is 4.x so it is important the version is specified especially when trying to register an IOS MTP device to UCM since this is an invalid media resource in SCCP version 4.x.

BR1-RTR(config)#sccp local FastEthernet0/0.11
BR1-RTR(config)#sccp ccm 10.10.201.1 identifier 1 version 7.0
BR1-RTR(config)#sccp

A UCM group containing a list of Call Control Agents needs to be specified to support redundancy. In a stand alone UCME environment only a single Call Control Agent might be provisioned but in a UCM environment the Subscriber UCM, Publisher UCM and backup SRST CME gateway are the priority 1, 2 and 3 Call Control Agents respectively.

BR1-RTR(config)#sccp ccm group 1
BR1-RTR(config-sccp-ccm)# associate ccm 1 priority 1

The profile defining the characteristics of the conference bridge will be the next bit of configuration required. The codecs are defined and the maximum sessions specified. The DSPFarm will also need to be associated to the SCCP protocol at this stage (no other options at the time of writing).

BR1-RTR(config)#dspfarm profile 1 conference
BR1-RTR(config-dspfarm-profile)# codec g711ulaw
BR1-RTR(config-dspfarm-profile)# codec g711alaw
BR1-RTR(config-dspfarm-profile)# codec g729ar8
BR1-RTR(config-dspfarm-profile)# codec g729abr8
BR1-RTR(config-dspfarm-profile)# codec g729r8
BR1-RTR(config-dspfarm-profile)# codec g729br8
BR1-RTR(config-dspfarm-profile)# maximum sessions 2
BR1-RTR(config-dspfarm-profile)# associate application SCCP
BR1-RTR(config-dspfarm-profile)# no shutdown

Each conference session supports up to 8 parties in the same conference call and consumes half a DSP (PVDM2-8). A single DSP (PVDM2-16) supporting conferencing cannot be used for any other media resource- therefore it makes sense to have an even number of conference sessions.

The DSPFarm profile will need to be associated with a SCCP Group- a unique name is given to the conference bridge and this name will serve as the SCCP unique identifier when registering to the UCME.

BR1-RTR(config)#sccp ccm group 1
BR1-RTR(config-sccp-ccm)# associate profile 1 register cvg-cfb

Within the telephony-service CLI the conference bridge needs to be added as a known media resource and the maximum number of DSP Units specified. The UCME will cease to use software conferencing as a result of specifying the “conference hardware” command.

BR1-RTR(config)#telephony-service
BR1-RTR(config-telephony)# conference hardware
BR1-RTR(config-telephony)# sdspfarm units 1
BR1-RTR(config-telephony)# sdspfarm tag 1 br1cfb

Registration of the conference bridge to the UCME can be verified using the “show sdspfarm units” command.

Placeholder ephone-dn’s need to be added to support the number of active Ad-Hoc conference participants required. These DN’s do not need to be dialable numbers (unlike the case of Meet-me conferences). In this example 4 conference participants will be allowed due to there only being 4 available channels associated with ad-hoc conferencing. The ephone-dn’s are providing the lines to anchor the call whereas the DSP resource is used for the transcoding and audio mixing required for conferencing.  Conversely, if there were no restrictions placed on the number of available channels, an octo-line could be used to support 8 conference participants.

ephone-dn  5  dual-line
 number A1000
 conference ad-hoc
 preference 2
 no huntstop
!
ephone-dn  6  dual-line
 number A1000
 conference ad-hoc
 preference 1
 no huntstop
!

Tones can be provided to conference participants as and when a person joins or leaves a conference call. The frequency and cadence (including the tone-on and tone-off durations) are defined within the “voice class custom-cptone” CLI.

BR1-RTR(config)#voice class custom-cptone CONF-LEAVE
BR1-RTR(cfg-cptone)# dualtone conference
BR1-RTR(cfg-cp-dualtone)#  frequency 400 800
BR1-RTR(cfg-cp-dualtone)#  cadence 100 50 200 50 300 50 400 50
BR1-RTR(cfg-cp-dualtone)#!
BR1-RTR(cfg-cp-dualtone)#voice class custom-cptone CONF-JOIN
BR1-RTR(cfg-cptone)# dualtone conference
BR1-RTR(cfg-cp-dualtone)#  frequency 1000 2000
BR1-RTR(cfg-cp-dualtone)#  cadence 100 50 200 50 300 50 400 50

The custom tones are then assigned to the DSPFarm profile.

BR1-RTR(config)#dspfarm profile 1 conference
BR1-RTR(config-dspfarm-profile)#shut

Disabling profile will disconnect active CONFERENCING calls,
do you want to continue ? [yes/no] yes

BR1-RTR(config-dspfarm-profile)# conference-join custom-cptone CONF-JOIN
BR1-RTR(config-dspfarm-profile)# conference-leave custom-cptone CONF-LEAVE
BR1-RTR(config-dspfarm-profile)#no shut

To verify an active conference call is using DSP resources on a particular gateway use the “show sccp connections” command. To solve any unusual problems start of by bouncing the SCCP application from within the IOS (no sccp/sccp).

Amy Ryan – CCIE #24677 (Voice)
Technical Instructor – IPexpert, Inc.
Mailto: aryan@ipexpert.com

Did you Miss our vLectures that were scheduled for this week & last week? No worries!

All our vLecture sessions are recorded and available for those who have missed our FREE vLecture and for participants who want to review the vLectures sessions again. We have saved the session recordings for you. Watch our world renowned CCIE instructors explaining specific technical topic in our technology-focused classes and capture the technical knowledge needed to increase your chances of passing CCIE exam.

CCIE Voice

• Instructor: Vik Malhi
• Topic: Cube
• Link: http://ipexpert.acrobat.com/p18636770/

• Instructor: Amy Ryan
• Topic: Unity Connection Integration
• Link: http://ipexpert.acrobat.com/p61951501/

Do not miss our vLectures scheduled for the coming weeks. If you’re an IPexpert client and wish to join these sessions, please be sure to reserve a “virtual seat” now, these have been highly anticipated and we’re quite confident that these online training seats will fill up quickly.

When dealing with call routing in general, it is no secret that there are countless ways to manipulate dialed digits to invoke a requested behavior.  Anyone who has began studying to achieve the Cisco CCIE Voice certification has become quite aware of the plethora of methods to utilize when completing the Call Routing sections of the lab blueprint.  It is quite possible when you sit the CCIE Voice lab to be asked to do some sort of Call Blocking as well, whether that is in the form of blocking calls to or from certain numbers, number type or even blocking calls based on date or time of day.    In this blog, we will focus on after-hours call blocking as it pertains to Cisco Unified Communications Manager Express (CUCME) or CME-as-SRST.  When implemented, calls matching against a pattern of specified digits will be prevented from proceeding based on day of the week and/or time of day.

CUCME call-blocking configuration applies to all SCCP, H.323, SIP and POTS calls that go through the CUCME router. All incoming calls to the router, except calls from an exempt phone, are also checked against the after-hours configuration.  Lets take a quick glance at a sample configuration to see how this is applied.

telephony-service

after-hours block pattern 1 9011
after-hours block pattern 2 1212
after-hours block pattern 3 1617 7-24
after-hours date Dec 25 12:00 23:59
after-hours day Sun 12:00 07:00
after-hours day Mon 19:00 06:59
after-hours day Tue 19:00 06:59
after-hours day Wed 19:00 06:59
after-hours day Thu 19:00 06:59
after-hours day Fri 19:00 06:59
after-hours day Sat 13:00 12:00

In this example, calls made beginning with pattern 9011, 1212 or 1617 are blocked during the above schedule.  In this schedule, each day of the week has a defined time for blocking calls to the listed patterns.  There are a couple of things to take into consideration when setting up the time of day in this fashion.  Let’s use Monday as an example.  Based on above, calls are blocked on from 7pm Monday evening until 7am exactly Tuesday morning.   Anytime the first timestamp listed is of a higher number than the second timestamp listed, we know that the second timestamp indicates the time of the following day.  In addition, if we had used “07:00” instead of “06:59” here, then calls would have been blocked until 7:01am on Tuesday morning.  If we made this error on the day it counts, those points would be lost for us.  The above example also shows these types of calls cannot be made at anytime on December 25.  It further shows that calls matching pattern 1617 will be blocked all hours of all days.

When dealing with blocked calls, it is important to remember the configuration applies globally to all dial peers.  However, it may be requested to allow certain phones to be exempt when placing these types of calls.  There are a few methods that can be used to achieve this, such as at the individual directory number, phone-level or dial-peer.  It can also be set up so Individual phone users can override call blocking utilizing a PIN that has been assigned, however this method does not work on patterns that are blocking 24 by 7 such as pattern 3 in our example above.

Call Blocking Exemption for a Directory Number or Individual Phone

This method exempts all directory numbers associated with a phone from the after-hours call blocking configuration.

ephone 1
after-hour exempt
!
voice register dn or pool 1
after-hour exempt
To verify this:
BR2-RTR#sh ephone 
ephone-1[0] Mac:0024.142E.5BD1 TCP socket:[-1] activeLine:0 UNREGISTERED
mediaActive:0 offhook:0 ringing:0 reset:0 reset_sent:0 paging 0 debug:0 caps:0
IP:0.0.0.0 0 Unknown 0  keepalive 0 max_line 0
Preferred Codec: g711ulaw
after-hour exempt
BR2-RTR#sh voice register dial-peer  (SIP PHONES)

Call Blocking Exemption for a Dial Peer

This method allows H.323 and SIP trunk calls to proceed in spite of the after-hours configuration.  This is critical to remember as you could be doing TEHO routing of some fashion that would be prevented from occurring if you did not exempt the incoming voip dial peer from being blocked.

dial-peer voice 100 voip
incoming called-number .
paramspace callsetup after-hours-exempt  true
To verify this:
BR2-RTR#sh dial-peer voice
VoiceOverIpPeer100
……..
incoming call blocking:
translation-profile = `'
disconnect-cause = `no-service'
advertise 0x40 capacity_update_timer 25 addrFamily 4 oldAddrFamily 4
mailbox selection policy: none
type = voip, session-target = `',
technology prefix:
settle-call = disabled 

Amy Ryan – CCIE #24677 (Voice)
Technical Instructor – IPexpert, Inc.
Mailto: aryan@ipexpert.com

Have you ever wanted to attend one of IPexpert’s industry-leading CCIE classes?
Have you ever had problems really understanding a specific technical topic?

Do you want to improve your chances at pass the CCIE Lab?

Do you want to see why IPexpert’s  CCIE instructors are considered the best in the training industry?

Do you want IPexpert, the company who has trained more CCIEs in the world, to help you?

…How would you like some FREE CCIE Lab training?

IPexpert is now offering FREE online training sessions to all IPexpert clients. If you want to improve your chances at passing Cisco’s rigorous and prestigious CCIE certifications, or if you simply want to fully-understand a specific technical topic – you can’t miss our FREE Online vLectures! Several times a week, you will be able to sit in, watch and interact with the IPexpert Instructor who will be teaching technology-focused classes on a specific track and topic. If you’re an IPexpert client and wish to join these sessions, please be sure to reserve a “virtual seat” now, these have been highly anticipated and we’re quite confident that these online training seats will fill up quickly.

CCIE Voice:

• Date / Time: Aug 17^th at 4 PM EST
• Instructor:  Amy Ryan
• Topic: Unity Connections Integrations

If you’re interested in this FREE online session, click here to Schedule Now!

CCIE Routing and Switching:

• Date / Time: Aug 19^th at 10 AM EST
• Instructor:  Marko Milivojevic
• Topic: Interdomain Multicast Routing

• Date / Time: Aug 24^th at 10 AM EST
• Instructor:  Marko Milivojevic
• Topic: Frame Relay – From Basics to QoS

If you’re interested in this FREE online session, click here to Schedule Now!

CCIE Service Provider:

• Date / Time: Aug 19^th at 10 AM EST
• Instructor:  Marko Milivojevic
• Topic: Interdomain Multicast Routing

If you’re interested in this FREE online session, click here to Schedule Now!

Couple of months ago, I wrote an article on various convenient methods of accessing ProctorLabs CCIE rack rental devices. That article focused on Windows users. This is part two of that series, with focus on students using Mac or Linux.

The biggest challenge for Mac and Linux users is selecting good terminal program to use. There are many choices, but they all share almost the same difficulty – lack of consistency in supporting “bookmarks”, or in some cases, even the basic lack of support for tabs.

With this in mind, we looked into what these platforms had in common and we found one thing. By default, they all support CLI access to terminal, regardless of which application is in use. Many power users are quite happy to use command line to access our rack rental anyway. Capitalizing on that and making that single task is the approach we took. Before I examine that in more detail, here is something very nice for our Mac users.

SecureCrt for Mac

SecureCRT beta is now available for download from the manufacturer, VanDyke. We tested our bookmark set with Mac version and it works flawlessly! Good job, VanDyke.

You can download SecureCRT bookmarks from here: ProctorLabs-SecureCRT.zip

IPexpert’s PodConnect

IPexpert’s approach to remote Pod access from Mac and Linux is quite simple. When you are in your CLI, simply type the command “PodConnect.pl r1″ and you will be connected to the R1 on the ProctorLabs pod you choose as default. If you specified your username and password, PodConnect will log you in. You are now ready to work. Take a look at the example session I use:

Mac ~> PodConnect.pl r2
Trying 74.126.20.111...
Won't send login name and/or authentication information.
Connected to pod111ts1.proctorlabs.com.
Escape character is '^]'.

         ****PROCTOR LABS, INC. SECURE ONLINE RACK SYSTEM****
      WELCOME to Proctor Labs, Inc. CCIE preparation vRack.

    WARNING:  This system is for the use of authorized clients only.
          Unauthorized access is a violation of federal, state,
                        civil and criminal laws.

http://www.ProctorLabs.com

User Access Verification

Username: myusername
Password: 

            You are on line number: 2

R2#

That’s all I have to do. Regardless of the terminal emulator program I use, it will work. Here’s how you install it.

• Make sure you have Perl installed.
• Make sure you have Expect and Perl Expect module installed.
• Download the PodConnect.zip file.
• Unzip the file into the folder in your path. Personally, I use $HOME/bin for this
• Make the file executable: chmod 700 PodConnect.pl
• Try it out!

If you run PodConnect.pl, you will probably notice error message telling you that you need to specify the Pod. You can do that after the device name. For example, running “PodConnect.pl r1 111″, will connect you to the R1 on Pod #111. You can set the default pod by setting “PL_POD” environment variable.

Once you run the Pod, if environment variable PL_USERNAME and PL_PASSWORD are set, PodConnect.pl will attempt to automatically log you in using those credentials. If those variables are not set, you will need to log-in manually.

To make things even quicker, here are couple of tricks you can do. Add the following lines to your $HOME/.profile:

alias c="$HOME/bin/PodConnect.pl"
export PL_POD="111"
export PL_USERNAME="myusername"
export PL_PASSWORD="mypassword"

Next time you open the terminal, you should be able to connect to ProctorLabs devices in your pod by simply typing “c device”, like this:

Mac ~> c r2
Trying 74.126.20.111...
Won't send login name and/or authentication information.
Connected to pod111ts1.proctorlabs.com.
Escape character is '^]'.

         ****PROCTOR LABS, INC. SECURE ONLINE RACK SYSTEM****
      WELCOME to Proctor Labs, Inc. CCIE preparation vRack.

    WARNING:  This system is for the use of authorized clients only.
          Unauthorized access is a violation of federal, state,
                        civil and criminal laws.

http://www.ProctorLabs.com

Username: myusername
Password: 

            You are on line number: 2

R2#

NOTE: If you store your password in .profile, make sure the file is readable only by your user account. The best way to ensure this is to set permissions to 600 on it (chmod 600 ~/.profile).

Enjoy your studies!

–
Marko Milivojevic – CCIE #18427
Senior Technical Instructor – IPexpert
Join our Online Study List

Have you ever wanted to attend one of IPexpert’s industry-leading CCIE classes?
Have you ever had problems really understanding a specific technical topic?

Do you want to improve your chances at pass the CCIE Lab?

Do you want to see why IPexpert’s  CCIE instructors are considered the best in the training industry?

Do you want IPexpert, the company who has trained more CCIEs in the world, to help you?

…How would you like some FREE CCIE Lab training?

IPexpert is now offering FREE online training sessions to all IPexpert clients. If you want to improve your chances at passing Cisco’s rigorous and prestigious CCIE certifications, or if you simply want to fully-understand a specific technical topic – you can’t miss our FREE Online vLectures! Several times a week, you will be able to sit in, watch and interact with the IPexpert Instructor who will be teaching technology-focused classes on a specific track and topic. If you’re an IPexpert client and wish to join these sessions, please be sure to reserve a “virtual seat” now, these have been highly anticipated and we’re quite confident that these online training seats will fill up quickly.

CCIE Security:

• Date / Time: Aug 10^th at 10 AM EST
• Instructor:  Tyson Scott
• Topic: DMVPN

If you’re interested in this FREE online session, click here to Schedule Now!

CCIE Voice:

• Date / Time: Aug 12^th at 1 PM EST
• Instructor:  Vik Mahli
• Topic: Cube

• Date / Time: Aug 17^th at 4 PM EST
• Instructor:  Amy Ryan
• Topic: Unity Connections Integrations

If you’re interested in this FREE online session, click here to Schedule Now!

CCIE Routing and Switching:

• Date / Time: Aug 19^th at 10 AM EST
• Instructor:  Marko Milivojevic
• Topic: Interdomain Multicast Routing

If you’re interested in this FREE online session, click here to Schedule Now!

CCIE Service Provider:

• Date / Time: Aug 19^th at 10 AM EST
• Instructor:  Marko Milivojevic
• Topic: Interdomain Multicast Routing

If you’re interested in this FREE online session, click here to Schedule Now!

First of all let’s start proceedings with the disclaimer. H323 is an ITU protocol used to set up VOIP calls between two endpoints  (conferences, gateways, terminals) sitting on  the network. It is a very, very complex umbrella protocol with many sub-protocols from ITU and IETF referenced/defined. Not to mention the copious amounts of revisions that have taken place over the past 15 or so years.  Needless to say, this blog is not going to be a full comprehensive guide to H323. It is however a streamlined summary (kind of a fast start guide :-) of what is most relevant based on the CCIE Voice Lab blueprint. We will focus in this blog on the H323 messaging involved in a call between UCM & UCME via a gatekeeper.

Calls between UCM & UCME via a gatekeeper

In reality, the fact that we are dealing with UCM and UCME is insignificant. You can treat this situation as a call between  two H323 endpoints (gateways).

In this example let’s think of the UCM and UCME as Endpoint 1 and 2 respectively which are both registered to the same Gatekeeper. The same call flow is applicable when you consider Endpoint 1 & 2 as two UCM clusters, two UCME’s or two H323 gateways registered to the same Gatekeeper.

Endpoint 1 (calling endpoint) initiates the ARQ (1)/ACF (2) exchange with that Gatekeeper. Contained within the ARQ is a bandwidth request (16kbps and 128kbps for G729 and G711 respectively) and also a telephone (E164) number. The Gatekeeper shall return the Call Signaling Channel Transport Address of Endpoint 2 (called endpoint) in the ACF. You can use the debug gatekeeper main 10 to see how gatekeeper resolves the E164 number and debug gatekeeper call 10 to see the incoming bandwidth request from Endpoint 1. If either the called number cannot be resolved or the bandwidth request is unsuccessful, an ARJ message is returned to Endpoint 1.

Endpoint 1 then sends the Setup (3) message to Endpoint 2 using the Transport Address contained within the ACF message from Gatekeeper. If Endpoint 2 wishes to accept the call, it initiates an ARQ (5)/ACF (6) exchange with the Gatekeeper. It is possible that an ARJ (6) is received by Endpoint 2, in which case it sends Release Complete to Endpoint 1. Endpoint 2 responds with the Connect (8) message which contains an H.245 Control Channel Transport Address for use in H.245 signaling.

You are able to see a high level view of the RAS messaging using the debug ras command on the gatekeeper. The beauty of this command is that is shows the IP addresses of the source/destination in decimal format. In order to see the entire RAS message use the command debug h225 asn1 on the gatekeeper. This command produces  A LOT of output and should be used sparingly! If it wise to increases the RRQ keepalive timer to avoid the RRQ/RCF keepalive mechanism from flooding the debug output on screen/log. You are able to do this within UCM from system > gatekeeper and from UCME using the command ras rrq ttl within voice service voip/h323. I suggest 5 minutes as a reasonable value. The debug h225 asn1 command could be used on Endpoint 1 and/or 2 which would in addition to the RAS messaging that particular endpoint exchanged with the gatekeeeper show you the H225 Call Signaling messaging (Setup, Call Proceeding, Alerting, Connect).

Location Request

If Endpoint 2 was registered to another Gatekeeper (Gatekeeper 2) then Gatekeeper 1 would contain a zone prefix to a remote zone which has been defined on Gatekeeper 2. Endpoint 1 (calling endpoint) sends an ARQ (1) to Gatekeeper 1. Gatekeeper 1 sends an LRQ (2) to locate called Endpoint 2. Gatekeeper 2 returns an LCF (3) with the Call Signaling Channel Transport Address of the Endpoint 2. This information is passed onto Endpoint 1 inside the ACF (4) message. Endpoint 1 would then send a Setup message to the Call Signaling Address of Endpoint 2 and the H225 messaging would continue in an identical manner in the previous example.

H245 Messaging

The H225/RAS messaging discussed up to now is responsible for finding the location of the called party. The called party will ring and the calling party will hear ringback. Once the call has been answered then a whole new messaging (H245) sequence  is initiated. This H245 messaging is responsible select the appropriate codec/dtmf transport mechanism used for the call and the endpoints RTP/RTCP channels to be used for the media being sent between the endpoints.

There are three main phases of H245 messaging which you are able to see using the debug h245 asn1 command.

(1) TCS. The Terminal Capability Set Message is sent between the endpoints involved in the call to indicate the codecs, dtmf and other capabilities of each endpoint. Each TCS Message must be acknowledged by the other endpoint. If there are no overlapping capabilities then you will see the Terminal Set Reject Message.

(2) MSD. Master/Slave Determination is used to determine the codec since the TCS messages could have indicated multiple codecs supported. The Master will decide the codec and other capabilities to be used in the call. The Master is chosen based on Endpoint type (gateway > terminal), Endpoint capabilities (video & audio > audio only) and randomly (identical endpoints).

(3) OLC. Open Logical Channel messages are used to inform each endpoint of the RTP/RTCP ip address/port numbers.

There is one variation to the above H245 messaging sequence- H245 FastConnect. This was introduced in H323 v2 and solves the problem of having the H245 handshake once the call has answered. In a nutshell when Fast Connect is used the Fast Start Information Element is contained in the SETUP message- this Fast Start IE contains the TCS Message. This allows capabilities Exchange to occur before the call has answered thereby meaning that logical channels are opened quicker compared with H323 Slow Start. The Called Party acknowledges the TCS and sends it’s own TCS in the Connect Message.

Vik Malhi – CCIE#13890
Managing Partner / Instructor – IPexpert Inc

Have you ever wanted to attend one of IPexpert’s industry-leading CCIE classes?
Have you ever had problems really understanding a specific technical topic?

Do you want to improve your chances at pass the CCIE Lab?

Do you want to see why IPexpert’s  CCIE instructors are considered the best in the training industry?

Do you want IPexpert, the company who has trained more CCIEs in the world, to help you?

…How would you like some FREE CCIE Lab training?

IPexpert is now offering FREE online training sessions to all IPexpert clients. If you want to improve your chances at passing Cisco’s rigorous and prestigious CCIE certifications, or if you simply want to fully-understand a specific technical topic – you can’t miss our FREE Online vLectures! Several times a week, you will be able to sit in, watch and interact with the IPexpert Instructor who will be teaching technology-focused classes on a specific track and topic. If you’re an IPexpert client and wish to join these sessions, please be sure to reserve a “virtual seat” now, these have been highly anticipated and we’re quite confident that these online training seats will fill up quickly.

CCIE Security:

• Date / Time: Aug 8^th at 10 AM EST
• Instructor:  Tyson Scott
• Topic: DMVPN

If you’re interested in this FREE online session, click here to Schedule Now!

CCIE Voice:

• Date / Time: Aug 12th at 1 PM EST
• Instructor:  Vik Mahli
• Topic: Cube

If you’re interested in this FREE online session, click here to Schedule Now!

We’re pleased to announce the launch of a service that’s been requested for years, a CCIE job / recruiting service. In the past we’ve attempted to partner with various firms, but in the end – it just didn’t work. So – if you’re a CCIE (or even a CCVP or CCNP) and you’re seeking a new job or interested in hearing about new career opportunities – or, if you’re on the opposite end of the spectrum and you’re the company, organization (or even another recruiting firm) looking for the ideal high-end CCIE for a job opening you have – I encourage you to visit Platinum Placement Services. You can also follow their Facebook, Twitter and LinkedIn social initiatives where various CCIE jobs will be posted periodically.

- Wayne