Unleash Networks Blog

Last evening, a group of enthusiastic telecom professionals from Chennai gathered at the Park Sheraton Hotel for the inaugural meeting of the Chennai telecom interest group. We hope to convene once a month to share our knowledge or to just hang out with people from the telecom / networking industry. Gokul also has coverage on his blog.

After  a round of introductions, we had people share their knowledge about VoIP, SIP, IMS, WiMAX, Mobile application delivery platforms, the entrepreneurial climate in India, the VC scenario in India, social networking, the state of Indian mobile operators, the technical direction of various European mobile operators, and so forth.  We even had Chandra  share his experiences with mobile services in Ethiopia and Somalia. Chandra is also an active member of the SIP forum.

Things got even more interesting after the arrival of Subbu, who is a consultant with the ETSI. He talked about the latest standards activities in the Mobile/IMS space. I must admit most of it went over my head, but it was just great to have a person with such technical depth in this group.

Some pics :

 

L->R : Nitin, Gokul (yes the VoIP blogger),  Vasu, Subbu (standing)

 

L->R : Madhu, Aravind, Anbu

 

L->R: Vijay Anand (blogger, entrepreneur, and brains behind Proto.In), Jayadev, Ravi, empty chair where Chandra was sitting a few seconds back

Credit must go to Vijay for taking the lead with getting this group together. I think he is one of the very few individuals in India who is solidly tuned to both the entrepreneurial and investor channels. (excuse the bad mobile pun) 

If you are interested in the technology side of telecom, VoIP, IMS, wireless, networking, or security please contact any of us or just show up at the next meeting.

Apologies : I got some names wrong in the first pass of this post.

[tags] chennai telecom, entrepreneur, voip, ims [/tags]

 

We just released the Unbrowse SNMP Scripting Guide and Code Samples.

You can access it  here 

Completely Free !

The entire scripting interface falls under the “Free Features” category. So, you can develop and run your scripts even after the “Power Features” trial period has expired.

Why script ?

While you can do a lot of things using the Unbrowse SNMP user interface, there are occasions where you want that little extra control. For example, you may want to leverage the passive trap receiver to write trap data to a MySql database as they appear, or to provide fast SNMP OID to Name lookups to your in-house application, or to import hundreds of router information from an external source such as Cisco Works DCR format. See sample code (VBScript)

Using this interface, you can write simple programs in VBScript or Ruby to twist Unbrowse SNMP to your needs.

Feedback

We have documented only the most important methods and properties of the scripting objects. If you need something you cant find, please contact us via email or our forum.

 

[tags] SNMP Scripting, Traps, MIB Browser [/tags]

Port mirroring or port spanning is a technique by which you can get a copy of packets from one or more switch ports sent to a network analyzer. Port spanning has become the most common mechanism to capture packets since the death of the ethernet hub.

The following picture shows packets from ports 1,2,3 being spanned to port 6. We have attached Unsniff Network Analyzer to port 6.

Duplicate packets

You can span packets into or out of a switch port. However, typically you want a copy of both. The problem is when both the ingress and egress ports are spanned, this may result in duplicate packets being seen by the network analyzer. The timestamps are different but the packet contents are the same. See here and here for more details of why this happens.

Note : You may even see more than two copies when switching broadcast, multicast, or frames with unknown unicast addreses.

Using Unsniff to eliminate duplicate packets

It goes without saying that these duplicates are a major headache. Unsniff has excellent support for culling duplicate packets. Unsniff can not only ignore duplicates but also triplicates or more.

Here is how you use the feature.

• Select “Tools->Customize->Advanced“
• Scroll down to the “Advanced Capture” section
• Set the “Filter duplicate frames” to “True” as shown below

• Duplicate filter mode : Controls how far back in time Unsniff checks for a duplicate. It also controls whether the headers (IP/Ethernet/etc) are used or whether a full packet is used to detect a duplicate. For most cases use “Normal”, for lightly loaded switches use “Quick”, use “Deep” for best results but it will slow down Unsniff.

Now you can start capturing packets from SPAN ports, duplicates are automatically culled and life is good again !

[tags] Cisco, Port SPAN, Unsniff, duplicate packets, network analyzer, sniffer [/tags]