2007 Oct 20 - Sat

Quality of Service Options on GRE Tunnel Interfaces

Note to self, according to Cisco's document 10106, Quality of Service Options on GRE Tunnel Interfaces: when applying queuing to a tunnel interface, shaping must also be applied. The top level policy of a recommended hierarchical policy should be a shaping command, while the lower-level policies configure the queueing mechanisms.

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2007 Aug 30 - Thu

Cisco Log Decoding

On the Cisco-voip mailing list, there was reference to a couple of sites that provide log decoders for Callmanger and IOS:

• TripleCombo Tool: Triple Combo is a tool to aid people troubleshoot CallManager problems by providing a listed output of SCCP, MGCP, Q931 / H225, H245 messages found in CCM traces, CCAPI/VTSP, Q931 and MGCP debugs in IOS gateway traces and versatile filtering capabilities.
• TranslatorX: TranslatorX allows you to quickly parse through Cisco CallManager trace files and search for Q.931, H.225, SCCP (Skinny), MGCP, or SIP messages.

They aren't necessarily TAC supported, but they may help to weed through and make sense of what would be otherwise painful troubleshooting.

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2007 Aug 15 - Wed

Asterisk Cisco CallManager Voicemail Integration
Asterisk Cisco CallManager Voicemail Integration

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2007 Aug 14 - Tue

Recording Calls in a Cisco Environment

In one of today's Cisco listserves, there were a few suggestions for Call Recording software:

• NICE Contact Center & Enterprise Products
• "run Asterisk and use it as your outbound/inbound gateway. Let it open a second connection to the actual destination, and record"
• "base something on pcapsipdump"
• Telrex
• Edigin
• Witness
• Comvurgent: "It works ok, but you have to manually type in the phone number for each call"
• CAllReplay
• Oreka: Oreka is a modular and cross-platform system for recording and retrieval of audio streams. The project currently supports VoIP and sound device based capture. Recordings metadata can be stored in any mainstream database. Retrieval of captured sessions is web based.

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2007 Jul 29 - Sun

Internet Based 911

For those of you setting up IP based telephone solutions and are needing to set up E911 connections, there are a number of ways to do this.

The typical way to do this is to ensure that analog or digital lines are available at each location being serviced. Then be sure to route all calls originating from those specific geographical areas are sent out the nearest POTS (Plain Old Telephone Service) line, ie, analog or digital line.

If this isn't possible, for one reason or another, there is an alternate way of doing this. There are internet based E911 services available. According to Robert Kulagows, you "setup something like a SIP trunk and route e911 calls to them. You'd tell them which DIDs are located in which city, and allow them to handle the 911 call and send it to the correct PSAP."

One provider who can do this is 9-1-1 Enable. According to their site, they are in the Pulver 100 and the Internet Telephony 2006 Product of the Year.

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2007 Jun 25 - Mon

Cisco Device Health

In Cisco's book, Top Down Network Design, one useful show command is 'show buffers'. Some useful SNMP statistics include:

• BusyPer. CPU busy percentage in the last 5-second period.
• AvgBusy1. 1-minute exponentially decayed moving average of the CPU busy percentage.
• AvgBusy5. 5-minute exponentially decayed moving average of the CPU busy percentage.
• LocIfInputQueueDrops. The number of packets dropped because the input queue was full.
• LocIfOutputQueueDrops. The number of packets dropped because the output queue was full.
• LocIfInIgnored. The number of input packets ignored by the interface.
• BufferElMiss. The number of buffer element misses. (You can also check misses for small, medium, big, large, and huge buffer pools.)
• BufferFail. The number of buffer allocation failures.

I've been doing most of my snmp statistics gathering on 5 minutes intervals. On some interfaces, it may be of value to step that up to 1 minute intervals. Of course, if my total collection time is over 1 minute, I may have problems with that.

From the same book, is this interesting statistic about why Window's file transfers over WAN links can go only 'so fast'. SMB acts like a ping-pong protocol. It can only send up to 32KB before requiring an acknowledgement. So if the delay is 50 ms end to end, and ignoring client and server delays, a client can receive at most 32 KB every 100 milliseconds, or 320 KB per second. This means that the maximum throughput is 2.56 Mbps, at best.

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2007 Jun 06 - Wed

Writing Callmanager Call Detail Records to Excel Spreadsheet

In an earlier article, I described how to access the Cisco Callmanager CDR tables to obtain billing records through the use of the Sybase DBI drivers for Perl. The database needs to be placed into "mixed mode" for this type of thing to work.

I've created two perl modules to make use of this technique: cdr2file.pm and billing2file.pm.

cdr2file.pm takes as input three parameters: an extension, a starting date, and an ending date. It creates an Excel spreadsheet using a temporary file name, which allows multiple requests to be processed simultaneously. The spreadsheet contains four worksheets: a list of inbound calls, a list of local calls, a list of long distance calls, and a list of internationally placed calls. The selection is based upon four digit extensions and the North American Dialling plan. The duration of each call is included. Because both the 'Original Called' and the 'Final Called' fields are included, one can determine which calls ended up going to voicemail or transferred elsewhere.

The other module, billing2file.pm, takes as input a starting date and an ending date. For all outbound calls placed within that date range, a summary spreadsheet is created. The first worksheet contains a summary of call duration by user with the following fields: Extension Number, Name of the Phone, Total Duration in Seconds, Total Duration in Minutes. Each line contains a hyper link to a worksheet containing the actuall call details for that extension. On the detail worksheet for each user, the following details are provided: Date the call was placed, extension number originating the call, the original called number, the duration in seconds for the call, the phone identifier, and the phone description. This spreadsheet makes it convenient to produce monthly billing reports by user. For large companies, this may not be suitable as a spreadsheet may not be able to handle enough rows or worksheets (a limitation of Excel).

By creating suitable web pages, say through mod_perl or mason, members of the accounting department have direct, easy, live access to the Callmanager Call Detail Records in a ready to use format.

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2007 May 18 - Fri

Using a USRobotics Modem for Out of Band Management (OOB)

In configuring an older 33.6Kbps US Robotics modem for accepting auto-dial-up calls into a router, here are a few items to know:

• Use 'at&f1&b1&w0&w1y0' to force the modem to speak at 9600 to the router
• use 'ati5' to confirm new communications rate setting
• I seem to recall that all dip switch settings are in the up position but for 2, 4, 8, which are down

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2007 May 07 - Mon

Security Enhancements for Remote Access at Microsoft

Here is a link to a paper that has a bunch of useful stuff in it regarding Microsoft VPN's, IAS (Internet Authentication Server), security scripting, and Windows 2003 based Remote Access Infrastructure:

Security Enhancements for Remote Access at Microsoft: Technical White Paper

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User Certficate Auto Enrollment

With my 802.1x test setup, machine certificates were being sent to domain machines with no problem, but user certificates were not showing up.

In the group policy object, right on the container housing the users that needed certificates, I set the auto-enrollment settings. For some reason things weren't being inherited from the domain default policy. The group policy container is User Configuration -> Windows Settings -> Security Settings -> Public Key Policies -> Autoenrollment SEttings. The 'Enroll Certificates Automatically' needs to be checked along with it's two subsidiary check boxes.

The following command serves as a manual refresh of the policy:

gpupdate /target:user

Enrollment will take several minutes. Running the certmgr.msc mmc snap-in will allow one to check that the certificate has arrived in the Personal -> Certificates store.

The Application Event Log will contain success/failure status for the auto-enrollment.

I also found out from an troubleshooting auto-enrollment article, that domain users without email addresses will not auto-enroll. They don't need an actual email box, just an entry in the email attribute in Active Directory.

As further reference, Microsoft has an article on How Autoenrollment Works. There are other related and helpful articles in the same library section.

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