Tuesday 18 September 2012

NEC SL1000: Useful Networking Tips using Wireshark

Well as you know NEC SL1000 can support IP extensions & IP trunks (both SIP/H.323). In our setup for such services sometimes we encounter issues like extensions not registered, IP trunks not linked up. And therefore today i would like to introduce the usage of this network trouble-shooting tool known as Wireshark.

Wireshark used to be known as Ethereal for those who has used this tool before. I mean it is great that we can capture what is going on in the network but there are soo many information which are not relevant for our purpose. FYI before we can capture any network traffic, we need to ensure that the port where you are connecting your PC can 'see' network traffic going on elsewhere (for example at port 16 where your NEC SL1000 VoIP card is connected to). There are 2 ways to capture network traffic; port mirroring & using a network hub.

After we have captured the network packets, we can make use of filter command to 'see' the things we want to see;

  • sip (this command allows us to see only the SIP communications between NEC PBX & end-points) 
  • ip.src==x.x.x.x (this command allows us to see traffic coming from x.x.x.x under Source field)
  • ip.src==x.x.x.x (this command allows us to see traffic coming from x.x.x.x under Source field)
  • ip.src==x.x.x.x&&ip.dst==x.x.x.x (this command allows us to see traffic coming from both x.x.x.x under Source field, x.x.x.x under Destination field)

These commands are very useful to perform your network trouble-shooting. 

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