Cisco Cisco MGX 8240 Private Line Gateway Leaflet
ATM vs. TDM
FA C T SH EE T
O
V E R A L L
C
O M PA R I S O N
I s s u e
T D M
AT M
R e m a r k s
Cost of ownership
ee
eeeee
ATM lowers recurring bandwidth and operation costs
Bandwidth efficiency
e
eeeee
ATM enables different applications to share bandwidth while preserving QoS
Multiservice
eee
eeeee
ATM delivers multiservice capability without affecting bandwidth efficiency;
TDM provides multiservice capability at the expense of bandwidth efficiency
TDM provides multiservice capability at the expense of bandwidth efficiency
Quality of service
eee
eeee
ATM enables QoS without affecting bandwidth efficiency; TDM enables QoS at the
(QoS)
expense of bandwidth efficiency
Scalability
ee
eeeee
ATM networks can evolve to support emerging bandwidth-intensive applications
L
I M I T A T I O N S O F
T D M
L i m i t a t i o n
W h y
D e t a i l
High recurring
Bandwidth
• Bandwidth is wasted with statically mapped CBR-like connections (MCR=SCR=PCR)
bandwidth cost
inefficiency
• During periods of no traffic, bandwidth is not reassigned to other applications
• Inability to efficiently accommodate bursty data applications
• When all available bandwidth is allocated, additional bandwidth must be procured
• Inability to efficiently accommodate bursty data applications
• When all available bandwidth is allocated, additional bandwidth must be procured
Limited application
QoS is delivered
• Cannot support bursty data, even during periods of voice silence, because
performance
at the expense of
bandwidth is statically allocated
bandwidth; limited
bursting capability
bursting capability
Limited scalability to
Bandwidth generally
• Increasing traffic and new applications require a migration path to
support traffic growth
limited to T3/E3;
broadband connectivity
and new applications
no trunking over
• Architecture is not optimal for broadband services, especially for New World
public ATM services
IP-based applications
• Public ATM services cannot be used for trunking
A
D VA N TA G E S O F
AT M
A d v a n t a g e
W h y
D e t a i l
Savings in recurring
Bandwidth
• Bandwidth is dynamically shared among all applications
bandwidth cost
efficiency gained
• Multiservice integration saves bandwidth
with statistical
• Silence suppression for voice and repetitive pattern suppression for circuit
multiplexing
data save bandwidth
• Use of public ATM services for trunking provides a cost-effective alternative
to leased lines
Enhanced application
Efficient traffic
• ABR with VS/VD enables monitoring and adjusting of the cell rate of
performance
management
connections, avoiding congestion
optimizes application
• Large dynamically assigned buffers
throughput
Guaranteed QoS
User applications
QoS is guaranteed with:
levels for different
firewalled and fair
• Per-virtual circuit queuing
applications
allocation of excess
• Per-virtual circuit rate scheduling
bandwidth pro v i d e d
• Multiple classes of services (CoSs), including CBR, RT-VBR, NRT-VBR, UBR, ABR
Scalable
Evolution enabled
• Traffic growth is accommodated by offering a migration path to
architecture to
to broadband
broadband networking
support new
connectivity
• Architected specifically for multiservice networks—enabling New World applications
applications
Smooth migration
Seamless integration
• TDM CoSs and native ATM CoS are supported
path from TDM
into existing
• Legacy interfaces (X.25, circuit data, voice) and native Frame Relay or
environments
ATM are supported
e = very poor
ee = weak
eee = fair
eeee = good
eeeee = excellent