284 Chapter 7: Managed Multiservice Networks and Packet Voice VPNs
• Customers who would prefer to outsource the management of their WAN.
• Customers who need to improve the efﬁciency and reduce the overall cost of their
networks. Speciﬁcally, retail and ﬁnancial enterprises have beneﬁtted from MMS
Peer-to-Peer Managed Multiservice Networks
A peer-to-peer MMS network is a network that has the same architecture as the older, data-
only networks, as shown in Figure 7-1. Each customer has data and voice trafﬁc coming in
from edge CPE devices resident at their various customer sites.
Figure 7-1 Peer-to-peer MMS network architecture.
This architecture is designed primarily for customers that are outsourcing their enterprise
WANs. Note that the trafﬁc on the network is from one Company X location to another
Company X location. A peer-to-peer MMS network is not well suited for SP value-added
services offered on common or shared equipment accessed by multiple end customers such
as voice VPNs or Uniﬁed Messaging services. In contrast, there is additional secure trafﬁc
on a voice VPN between different customers and trafﬁc from customers to shared servers
that provide services such as Uniﬁed Messaging or web applications.
Peer-to-Peer Managed Multiservice Networks 285
Peer-to-Peer MMS Network Elements
A peer-to-peer MMS network has a relatively simple architecture consisting of the
• CPE router(s)—This is typically a Cisco 2600 series, 3600 series, or MC3810
concentrator. Customer data trafﬁc enters the SP network through this router, which
is typically connected by an Ethernet or Token Ring LAN on the customer side, and
a Frame Relay, ATM, or IP connection on the SP side.
The customer PBX, phone sets, and/or key system are also connected to this router
and are responsible for originating and terminating the voice trafﬁc. Earlier
incarnations of MMS networks frequently used Voice over Frame Relay (VoFR) and
Voice over ATM (VoATM) technologies. Many of the carriers that currently offer
VoFR or VoATM solutions are planning or considering VoIP-based services, to either
replace or augment their existing services.
A variation on CPE voice trafﬁc that is also under consideration is IP telephony. In
this architecture, the CPE router doesn’t originate or terminate the voice. IP phones,
softphones, and/or other H.323, SIP, or VoIP endpoints originate and terminate voice
trafﬁc, and the CPE router aggregates and routes the trafﬁc destined for the SP
backbone. More challenges (billing, security, call admission control, and so on) exist
with this design than with traditional telephony equipment connecting via the CPE
router (which also acts as the voice gateway).
• SP Points of Presence (POP)—These are geographically dispersed aggregation
points of CPE trafﬁc that typically use Frame Relay or ATM connectivity.
• SP backbone—The backbone carries trafﬁc between the POP, usually using an ATM-
based, high-speed network (Frame Relay is more often used as a CPE access
• Network management—The premise of an MMS network is that it can be managed.
SPs run elaborate Network Operations Centers (NOCs) where the status of the
network is monitored and alarms are raised when outages occur. SPs can use Cisco
management platforms such as CiscoWorks, or they can write their own applications
and use various products as elements in their network management scheme.
There is also a network management overlay network, typically using a separate PVC
to the CPE equipment and separate IP addressing, to carry SNMP and remote-access
trafﬁc to allow the SP to gather the information necessary to manage the network.
• Billing—This function is key to the SP’s ability to charge accurately for services
rendered. Peer-to-peer MMS networks tend to use a relatively simple, ﬂat-rate basis
for billing, such as CPE access bandwidth or committed information rate (CIR).