layer 2 cos and layer 3 dscp

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Feb 5th, 2010
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I have 3750 series switches whic h modify the voip cos to cos 5, these act like a layer 2 devices. The switches are connected to ASA 5500 firewall and firewalls to WAN, How can i implement the layer 3 dscp marking on switches or firewalls? if i apply on the switches, will the firewall trust the marking or forward these with out it. Do the firewalls ASA 5510 supports the dscp marking of packets?

Your help will be higly appriciated on this matter.


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Anthony Chambers Wed, 02/10/2010 - 20:34
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Do you have Cisco IP phones connected to these 3750 switches? If so the Cisco IP phones by default will mark all Voice payload traffic as DSCP EF. Unless configured the firewalls shouldn't modify any of the DSCP fields.

mrbzumrbzu Mon, 02/15/2010 - 04:53
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I am remarking the packets on the swicth with cos 5. is the cisco ASA can do the packet marking with dscp values for voice traffic?

Many thanks


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