7
votes
Accepted
Is TCP slow start supposed to be enabled for VoIP SIP?
Should TCP slow start be used with SIP-over-TCP?
SIP does not transfer large data with TCP. SIP is only used for signaling, the transport of the actual data (voice, video, ...) is done with RTP and ...
- 2,398
6
votes
Is a 10/100 switch sufficient for Voice?
If only phones are connected to the switch, you should be fine. If you also have PCs connected in tandem (switch<->phone<->PC), then you need to worry about QoS capabilities on the switch.
- 67.9k
5
votes
Accepted
How does a switch handle 2 VLAN's on same port such as voice + access vlan
You almost answered your own question: VOIP packets are tagged with the VOIP VLAN tag, internet packets are untagged, since that's the native VLAN on that port.
- 17.4k
4
votes
Accepted
Whats the difference between VOICE VLAN and ACCESS VLAN
Traditionally with Switching, there are two types of ports:
Access Ports -- ports which carry traffic for only one VLAN
Trunk Ports -- ports which carry traffic for multiple VLANs
In a scenario ...
- 15.1k
4
votes
Whats the difference between VOICE VLAN and ACCESS VLAN
The access VLAN is what is used for devices, such as PCs, connecting to the switch interface.
VoIP phones can use CDP (or possibly LLDP, depending on the model and switch configuration) to negotiate ...
- 100k
4
votes
Accepted
Best Practice for Voice and Data VLAN on single port
802.1Q tagging allows you to run multiple VLANs over a single, physical link. With phones, often the normal PC client VLAN remains untagged (access VLAN) while the VoIP VLAN is tagged.
Using a DHCP ...
- 86.4k
3
votes
Accepted
What are reasons to configure a Voice VLAN using the Auxillary VLAN feature instead of a Trunk + Native vLAN
Option 1 carries some security risk because broadcast and flooded traffic for the VoIP VLAN will be sent to the interface, even if there is no phone attached. Also, most PCs do not understand VLAN ...
- 100k
3
votes
Accepted
Auto Voice VLAN on Catalyst 2960X running IOS 15.2(2)
This is done all the time. Under a switch interface, you simply define a voice VLAN with the switchport voice vlan command. Something like this:
interface range GigabitEthernet1/0/1
switchport ...
- 100k
2
votes
Forward single DID number to sip trunk
I have a solution working with a Cisco 2800 acting as a Session Border Controller (CUBE) in front of an Asterisk box.
The inbound patterns and outbound patterns don't overlap (for me) so its a matter ...
- 61
1
vote
Can we use VRFs for BW preservation across the MPLS network?
I believe you mean VPN, not VRF. A VRF is a routing instance local to the router.
Creating a separate VPN will likely do nothing to help your voice traffic. If the backbone is congested, then ...
- 67.9k
1
vote
Cisco Voice VLAN (DHCP not working)
Cisco switches use CDP (default) or LLDP to negotiate a trunk with a phone acting as a switch on an access interface. Since you are using non-Cisco phones, you must either enable LLDP (if your phone ...
- 100k
1
vote
Accepted
PSTN Connection
"just in a lab" and "few extensions" makes me think your PSTN calls will be few; in which case you're better off with a SIP supplier, local to your country.
- 16.3k
1
vote
Is a 10/100 switch sufficient for Voice?
A 10/100 switch should suffice from a bandwidth perspective. But I would recommend considering a Gigabit switch for it's full duplex capabilities if your existing 10/100 (FastEthernet) switch is only ...
- 269
1
vote
DHCP not working in Voice Vlan
With the port set to
switchport mode access
and
switchport access vlan 250
your PC should grab the correct DHCP address.
Yes, you should be able to have 2 voice VLANs. https://supportforums.cisco....
- 367
1
vote
Unable to register 2 phones in Call Manager - Lab
Another possibility is that the phones were receiving incorrect Voice VLAN or DHCP settings (option 150 TFTP server in particular), ore were otherwise unable to contact the CUCM server at 192.168.10.5 ...
- 231
Only top scored, non community-wiki answers of a minimum length are eligible