Has anyone tried the Linksys SRW224P? 24 Port managed switch, 10/100, 2 Gig
Uplink Ports, PoE:
a.. Delivers reliable power over 10/100 Ethernet ports using IEEE 802.3af
standard
b.. Secure management via SSH/SSL and secure user control via 802.1x & MAC
filtering
c.. IGMP snooping, L2/L3 COS, queuing & scheduling makes solution ideal
for Voice/Video
d.. Intelligent traffic management with Rate Limiting, Policing ACLs, and
Storm control
All that for around $450....we have not put one of these through any heavy
duty production stress tests, but I was amazed at the features on this thing
for the price.
Cory J Andrews
++++++++++++
VOIPSupply.com
454 Sonwil Drive
Buffalo, NY 14225
++++++++++++++
voice - 716.630.1555 X22
email - [EMAIL PROTECTED]
AIM - B2CORY
----- Original Message -----
From: "mustardman29" <[EMAIL PROTECTED]>
To: "'Asterisk Users Mailing List - Non-Commercial Discussion'"
<asterisk-users@lists.digium.com>
Sent: Friday, February 24, 2006 8:01 PM
Subject: RE: [Asterisk-Users] What business IP phone to use
Interesting,
So are there any sort of specifications to look for? What your talking
about does not sound like a managed vs unmanaged issue. More like cheap
crap vs half decent. I would never want any switch to drop packets VoIP
or
not. Does not sound like QoS could help resolve that or jitter if the
conflicting packets both have SIP priority.
Managed switches used to imply higher quality but I think we are starting
to
see cheap and crappy managed switches coming onto the market. I would
still
choose a $500 unmanaged switch over a $100 managed switch. If the switch
is
doing it's job you should never have to view what is going on in there
anyways.
-----Original Message-----
From: Rich Adamson [mailto:[EMAIL PROTECTED]
Sent: Friday, February 24, 2006 9:43 AM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: RE: [Asterisk-Users] What business IP phone to use
> Aha, micro seconds in networking terms is normally written
usecs or us
> (actually it's the greek letter mu as in ulaw) rather than ms which
> are milliseconds seconds - what had me puzzled was that it
was stated
> that this could harm the voice path!
>
> > The difference can also cause unnecessary delays and
therefor echo
> > in the path. For example, procurve switches typically have 13ms
> > switching time, the high-end netgears about 21ms. As soon as you
> > stack a couple of switches you are talking 26ms vs 42ms
extra delay in the path!
>
> There is then only 8 usecs between the two switches, how on earth
> would this make any difference to the voice path at all?
Let alone induce any echo...
>
> Obviously the originally poster didn't understand the
difference. And
> based on this, he's probably advising people not to use Netgear
> switches for voice, oh dear.
I'll jump in here to make a couple of comments relative to
ethernet switches.
Not all switches are created equal!!!
If you take the cover off a switch, write down the part
numbers for the chips used, and read the doc on those chips,
you'll see major differences.
(We've actually tested several switches over the past several
years in real customer's networks as well.)
Many entry level switches on the market have only minimal
buffering for inbound and outbound packets. Its not uncommon
for output buffers to be limited to one or two packets, and
as a user, you can't chnage it.
Port congestion frequently shows up when two (or more)
devices connected to a switch (assume 100 mbs for now) try to
communicate via a single upstream port (assume 100 mbs for
now). The instantanous offered traffic is essentially 200
mbs, and the switch is expected to send that traffic out via
a 100 mbs port. For those devices with minimal buffering,
packets will be dropped. For newer switches with deeper
buffers, "some" packets will be held up in the chip's
internal queue waiting to get on the outbound port's wire.
The delay in the buffer will become jitter, and depending
upon exactly how many ports are contending for the outboud
port, the jitter _can_ become noticable. (That _is_ one of
the reasons why some switch vendors support QoS.)
One can talk about "wire speed throughput", etc, and it
doesn't mean squat. Those are all marketing and sales words,
not engineering specs.
There are plenty of very well known switch vendors that
purchase switches from other manufacturers and put their
names on the front covers. Some of those have characteristics
as noted above, while others manage the buffering and queuing
much better then what their marketing/sales words imply.
Its fairly common to see engineers in large corporate
networks using workgroup switches to consolidate traffic from
multiple wiring closets, and not pay any attention whatsoever
to "dropped packets" in the switches.
That's about the time when senior mgmt intervens and asks an
external company to assess their network performance to
resolve the internal fingerpointing. Our company has
completed many of these.
The _only_ way to know for sure what a switch is doing (eg,
dropping pkts) is to ensure the switches have some form of
network management. Even the simple Dell 2708 (eight port gig
switch for $100) has "some" level of mgmt in it. Certainly
not the best, but at least you can identify some issues.
With the pricing drops that we've all seen over the last
couple of years, its fairly easy to find managed switches at
very reasonable cost. I'd _never_ using unmanaged switches in
any environment where critical application data flows across
the net, and I'd suggest voip traffic represents "critical"
traffic in all production networks.
_______________________________________________
--Bandwidth and Colocation provided by Easynews.com --
Asterisk-Users mailing list
To UNSUBSCRIBE or update options visit:
http://lists.digium.com/mailman/listinfo/asterisk-users
_______________________________________________
--Bandwidth and Colocation provided by Easynews.com --
Asterisk-Users mailing list
To UNSUBSCRIBE or update options visit:
http://lists.digium.com/mailman/listinfo/asterisk-users
