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Asterisk Users 17 Comments

Pardon, this might be off-topic. I’m reading:


For a setup of ~5 agents, would I be wrong in thinking that a generic 16
port unmanaged switch would fit the bill?

The first model to come up for me in an Amazon search is:


Is this a reasonable choice? Would I be wrong in thinking that most any Fast Ethernet switch would be fine for Asterisk?



17 thoughts on - Switches

  • Hi,

    For a very basic setup it would work, but I would suggest POE at a minimum, and vlan support if possible.

    Gigabit uplinks, 10/100 for the poe ports



    Gigabit all ports



  • Hello,

    Yes, this kind of switches would work.

    VLAN and PoE support would obviously be better for convenience and security, but those are not mandatory.

  • B00AUEYX0Y/ref=sr_1_3?ie=UTF8&qid24462577&sr=8-3&keywords=netgear+poe

    Hypothetical: lag, choppy connection, dropped calls. Of course, I’d start with checking logs. How would I establish that the problem is that
    (some) of the ports aren’t gigabit?

    Small office, about five agents.



  • If your only running the phone on the port, there is no need for GigE to the phone, and many phones only support 100Mbit.

    If your running phones with built in switches, a computer off the phone, and the phone supports GigE, the GigE will help keep the computer from overloading the total available bandwidth, but that is a very low chance of being an issue to start with.

    GigE all ports vs GigE for your server, and 100Mbit for your phones really is not a major difference, but the price difference between the two is also very small now days, and you are buying equipment with a reasonable service life (3-8 years in my opinion), so it’s a balance between a few extra $ now, or waiting and seeing if you want it in the future, and paying some amount of money to swap it out.

    Most of the deployments I have done are with 100Mbit POE to the phones, and GigE for uplinks between switches and to the Asterisk server(s)


  • Had to run some small offices with SIP hardphones and basic switches. Unless you are doing things wrong (network loops…), your switch shouldn’t be an issue for such a small network. Depending on the voice codec you use, a VoIP conversation if a few kB/s, so don’t be obsessed with GigE.

    Some hardphones have an integrated switch. Don’t daisy chain phones this way, and be careful not to invert LAN and PC port.

    Bertrand LUPART

  • Any port with a hardware SIP phone plugged into it almost certainly won’t be gigabit 🙂 Anyway, an uncompressed (A-law or micro-law) voice connection is only using 64 000 bits per second. Compressed formats use even less bandwidth. The SIP signalling adds a bit of an overhead, but not much.
    That’s probably why most SIP phones have only 100 or even 10 meg ports.

    To be honest, you’ll probably be fine with a

  • Are you referring to the MAC CAM table? Saying ‘routing table’ and
    ‘switch’ in the same sentence seems confusing.

    Do VOIP devices take more table entries than other Ethernet devices? I.e. more than 1?

  • If your phones support PoE,

    I have had huge success with Zyxel:

    If you want to go even cheaper, I have successfully used these as well:

    Brian Franklin NTG, Inc. – “Problem Solved”

    —–Original Message—

  • No, ethernet switch works at lower / physical / MAC layer, NAT is ‘above’ that;
    so as long as everything is OK with your TCP/IP settings everywhere, a switch is entirely transparent to TCP/IP (or generally, when it’s encapsulated into MAC traffic).

    All that happens at a level totally transparent to the TCP/IP stack

    In a way, an Ethernet Switch is /the/ network near you, your cables are ‘just’ interconnects.


    el es

  • Remember that that zyxel 16 port switch is only 8 poe ports. If your phones are 802.3af or 802.3at, you could look at the ubiquiti line of switches.

  • so how does a client pc find the server if there’s no NAT? by IP
    address?? That makes no sense, to me, if the switch isn’t assigning addresses.


  • The ‘endpoint’ (pc, softphone, mobile, desk set, etc.) ‘finds’ the server’s IP address when:

    ) You configure the endpoint with the IP address or host name of the server. This happens either by a web page you fill out on the endpoint or a configuration file that is downloaded by TFTP, FTP, HTTP, etc.

    ) You configure SRV records in your DNS.

    I think the old IAXy did some sort of discovery on port 9999, but I don’t remember if it was device or server discovery.

  • +1 to what Kevin said, and

    there is a protocol running on pretty much every ethernet based network, named ARP : Address Resolution Protocol, by which ALL the clients learn ALL
    the surrounding clients (including the one that is the GATEWAY) MAC/IP combinations.

    Simplified, the encapsulation of ethernet packets is sort-of

    | MAC Header | IP Header | Packet
    |[MAC Source address][MAC Destination Address]|[Source IP][Destination IP]|[The rest of packet]

    [order and number of fields not necessarily real-life, for illustration purposes only]

    now the MAC source/dest fields are added AND REMOVED as needed when the packet passes from card to computer/router, then from computer/router to card; as the MAC fields don’t make sense in wider area networks;

    ‘dumb’ switches don’t participate/snoop in ARP, only store a table of what card MAC address they encountered on source MAC field of packets coming from that interconnect

    manageable switches /can/ participate and filter in the ARP process if told so and have such option.


    el es