Datasheet

Copyright © 1999 Cisco Systems, Inc. All Rights Reserved.
Page 5 of 11
Figure 5 Campus ATM Edge Router Integration of Voice, Dial, and WAN Applications
PBX
PBX
PBX
OC-3 ATM
Catalyst
®
5x00/
Catalyst 85x0
Ethernet/ATM Switched Campus LAN
with ATM uplink to Cisco 3600
Cisco
3640
Cisco
2600
Cisco
MC3810
Cisco
3620
Cisco
4700
Frame Relay
PSTN/Voice
and Dial
ISDN
Positioned on the edge of an ATM or Ethernet-switched
network, the Cisco 3600 with high-speed ATM provides the
abilityto support awide rangeofvoice and dataconnectivity
options such as ISDN and hybrid dial-access concentration,
Frame Relay, PPP, X25, or HDLC access, VoIP, voice over
Frame Relay (VoFR), synchronous and asynchronous WAN
aggregation, ATM25, or HSSI.
ATM Traffic-Shaping Feature
Traffic shapingis afunction typicallyprovided onATM edge
devices to ensure that bursty traffic conforms to predefined
parameters. Traffic shaping ensures that traffic from one VC
doesnot adverselyimpact anotherresulting in dataloss. This
function is very important when connecting to an ATM
WAN or public ATM network; especially when the ATM
switches enable traffic policing that will discard all traffic
that exceeds the predetermined contract at the ingress of the
switch.
The OC-3 network modules support Layer 2 per-VC
queuing and implement traffic shaping functionality using
UBR, UBR+, VBR-rt, VBR-nrt, ABR, or CBR ATM traffic
classes. Each of these service classes has a unique way to
shape traffic to specific customer requirements. For each
ATM service class,the ATMOC-3 network modulessupport
highly configurable parameters: peak cell rate (PCR),
sustainable cell rate (SCR), maximum burst size (MBS), and
minimum cell rate (MCR). These parameters can be defined
based on the specific bandwidth requirements of an
individual VC as needed for a specific application.
Supporting traffic shaping in the hardware means that there
is no performance degradation when shaping is enabled.
The Layer 2 per-VC queuing support for ATM traffic
shaping has a simple mechanism in place that ensures that
one, or a few, VCs do not consume all the transmit resources
onthe router.This is donebylimiting the numberof transmit
buffers available on a per-connection basis. This prohibits a
single VC or VP from oversubscribing all the transmit
resources of the interface. The OC-3 network modules have
only one transmit queue for all VCs. The minimum
configurable bandwidth is 64 Kbps. Even though a
contiguous range of bandwidth can be configured, the
granularity is limited to 37 Kbps.