[cisco-voip] Maximum number of T1 on 3845
Lelio Fulgenzi
lelio at uoguelph.ca
Wed Aug 27 20:19:11 EDT 2008
Thanks Nick. So then this is more of a concern when you are connecting to different carriers? I would suspect that unless you are in a big city or have diverse path circuits, chances are, one provider will have one clock since your circuits are from the same switch.
--------------------------------------------------------------------------------
Lelio Fulgenzi, B.A.
Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1
(519) 824-4120 x56354 (519) 767-1060 FAX (JNHN)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
"Bad grammar makes me [sic]" - Tshirt
----- Original Message -----
From: Nick Griffin
To: Gu Sang Jung
Cc: Lelio Fulgenzi ; Voice Noob ; Mordechai ; cisco-voip at puck.nether.net
Sent: Wednesday, August 27, 2008 7:39 PM
Subject: Re: [cisco-voip] Maximum number of T1 on 3845
I see your point on the 10 PRI circuits. Below is a great clocking discussion from Derick Winkworth post on the voip-forum titled "network-clock-participate" subject that I think Gu Sang is trying to hit on. The logic surrounding his description seems to apply to this discussion:
Quote:
In telco-land, there is the idea that all network switches are synchronized to the same clock. This is achieved by planning how a clock is distributed through your network. The idea is that there is one clock device in a network switch, called a PLL (phase-lock loop). The PLL will receive/recover the master clock on one of its bearer ports, or on a dedicated clock port called a BITS port.
All other ports on that switch/device will be timed using this master clock.
Cisco's ISRs were built using this model. There is one PLL on the motherboard, called the network-clock. Modules on your router may participate in this clocking scheme or not. Some have to, because they don't have their own PLLs/clocks on-board. When you need/want a module to participate in the network clock, you use the network-clock-select command. You select the master clock with the network-clock-select command. You can choose multiple master clocks and order them by priority. Only one is active at a time.
The implication here is that if you connect to multiple carriers (and thus multiple clock domains), you may/will end up with clock slips on one of the ports. Otherwise, you would set the telco port as the master clock and then time the rest of your private ports off of this. You may need to do this if you want the ISR to do TDM switching, for instance.
End Quote
On Tue, Aug 26, 2008 at 7:08 PM, Gu Sang Jung <gusangjung at yahoo.com> wrote:
This is my two cents.
The problem to load more than 10 PRIs will be timing issue.
the currently. Cisco 3845 only support 10 Time clock domain.
Hence, I designed to use only to max 10 PRIs into One 3845. If you have different telco clock on one 3845, these number should be limited with telco
If you provide clock from telco switch, Please make sure this. Otherwise, Fax, or Modem could be has issue.
----- Original Message ----
From: Lelio Fulgenzi <lelio at uoguelph.ca>
To: Voice Noob <voicenoob at gmail.com>; Mordechai <m.rabinovich at nves.ca>
Cc: cisco-voip at puck.nether.net
Sent: Tuesday, August 26, 2008 3:57:47 PM
Subject: Re: [cisco-voip] Maximum number of T1 on 3845
http://www.cisco.com/en/US/prod/collateral/routers/ps259/product_data_sheet0900aecd8057f2e0.pdf
i was referred to this by our SE. although the table says the 3845 will support 24 T1/PRI ports, the max simultaneous calls shows about 450 which is just under 20 ports (when dividing by 23, just under 19 when dividing by 24).
hope this helps.
--------------------------------------------------------------------------------
Lelio Fulgenzi, B.A.
Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1
(519) 824-4120 x56354 (519) 767-1060 FAX (JNHN)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
"Bad grammar makes me [sic]" - Tshirt
----- Original Message -----
From: Voice Noob
To: Mordechai
Cc: cisco-voip at puck.nether.net
Sent: Tuesday, August 26, 2008 5:54 PM
Subject: Re: [cisco-voip] Maximum number of T1 on 3845
No they don't. Where in the world did you get that from????
On Tue, Aug 26, 2008 at 4:47 PM, Mordechai <m.rabinovich at nves.ca> wrote:
3845 supports at least 16, more likely 24 pris if I remember right. We chose
them over 6509e with CMM blades because they provided appropriate density
and a newer voip platform.
-----Original Message-----
From: cisco-voip-bounces at puck.nether.net
[mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of Matthew Saskin
Sent: Tuesday, August 26, 2008 3:25 PM
To: Voice Noob
Cc: cisco-voip at puck.nether.net
Subject: Re: [cisco-voip] Maximum number of T1 on 3845
For one particular client I've got a series of 8 x 3845's with 12 PRI's
+ 230 configured xcoding sessions per device and no cpu/memory issues to
speak of. Nominal CPU utilization is around 35% with peaks of about 50%
during peak call times.
-matt
Voice Noob wrote:
>
> I think that device will support 12 or 14 PRI's. Don't remember off hand.
> On Tue, Aug 26, 2008 at 11:20 AM, Aman Chugh <aman.chugh at gmail.com
> <mailto:aman.chugh at gmail.com>> wrote:
>
>
> Just wanted to know if I can have 8 T1 pri terminate on Cisco 3845 ,
> any one already doing the same , any caveats that I need to be aware
> of , apart from the AS5300/5400 , what are my other options to
> terminate 8 T1 on a single router, I am putting in 6 PVDM2-64 to
> support this configuration.
>
>
> Aman
>
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