With frame relay, you don't actually have a "private circuit" in the same sense that you would with a point to point T1 for example. Instead, you order a PVC which is a virtual circuit between locations. The provider is supposed to guarantee a certain amount of bandwidth across a PVC that is at least equal to the CIR that you order. Under heavy traffic conditions, the provider will allow you to burst above the CIR up to perhaps several times your CIR but no more than the port speed of the frame switch. The actual amount of burst capability usually varies from provider to provider and some will allow bursts up to full port speed. This usually works quite well for data applications where occasional bursting may be required during large downloads etc, but where normal traffic is closer to the CIR. With voice, you may find that a larger CIR is required to guarantee that your voice bandwidth is sufficient to handle the number of simultaneous conversations that you are going to allow. If you are running only voice traffic across the PVC, then in order to guarantee that bandwidth, you may find that you need to order a PVC that is approaching or equal to your port speed. On the other hand, if you are running data across the PVC in addition to voice, then you might want to have a larger port speed to take advantage of the bursting capability. In that case, you would likely need to apply some traffic shaping such as QOS to prioritize your voice traffic. Another option is to have separate PVCs for voice and data traffic sharing the same access T1. When you first install frame, you will want to keep a close eye on latency and if necessary work with the provider to tune the PVC for better performance. They don't always give you the best path during the original provisioning but will generally work with you to improve performance if latency is a little high. You might also want to ask your provider about MPLS as an alternative to frame relay. MPLS can provide a similar level of service and possibly save you some money compared to the cost of frame relay with large CIRs.
-----Original Message----- From: David Sampson Sent: Thu, May 19, 2005 1:26 pm Does anyone else have info regarding the port speed matching the CIR? -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Eric Wieling aka ManxPower Sent: Thursday, May 19, 2005 11:55 AM To: Andrew Latham; Asterisk Users Mailing List - Non-Commercial Discussion Subject: Re: [Asterisk-Users] Public vs. Private Network >>I am looking at connecting 7 - 10 locations together using Asterisk and >>possibly some VoIP gateway appliances. I need to insure best voice quality >>as these trunks will be used primarily for customer calls. I am considering >>implementing a full T1 frame relay circuit to each location which can be >>done for a reasonable cost. DSL and Cable are currently at each location >>and setup for automatic failover. Should I remove one of my public >>connections and replace it with a private circuit for best quality? To run VoIP over Frame Relay you need your Port Speed to be the same as your CIR. Cisco has extensive docs about this, but I'm too lazy to look them up right now. -- Always do right. This will gratify some people and astonish the rest. Mark Twain _______________________________________________ Asterisk-Users mailing list Asterisk-Users@lists.digium.com http://lists.digium.com/mailman/listinfo/asterisk-users To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users _______________________________________________ Asterisk-Users mailing list Asterisk-Users@lists.digium.com http://lists.digium.com/mailman/listinfo/asterisk-users To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users _______________________________________________ Asterisk-Users mailing list Asterisk-Users@lists.digium.com http://lists.digium.com/mailman/listinfo/asterisk-users To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
