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SoftPhone issues

Dear Colleagues,

On page 88 of the "Designing the IP Telephony Network" guide from Cisco it is stated that SoftPhone is Layer 4 therefore traffic classification can only be done at first Layer 4 device in network. I agree with this however... when using NICs that support traffic classification (Intel, 3Com) I believe you can still classify SoftPhone traffic at the PC it originates from. Provided SoftPhone apps. is using a fixed port nr.

Two questions:

1. Is SoftPhone using a fixed port nr.?

2. Any experiences with this?

Many thanks in advance.

Best Regards,


Cisco Employee

Re: SoftPhone issues

1. For audio? No, it's a random UDP port between 16384 and 32767.

2. None here.

Keep in mind that with the proper switch capabilities (I will use a Cat6k as an example) that you can set COS (and I believe DSCP) -- based on the TOS coming in from the switchport, and Cisco IP SoftPhone should be setting the IP Precedence to 5.