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Cisco MGX 8230 Edge Concentrator Installation and Configuration
Release 1.1.31, Part Number 78-11215-03 Rev. B0, May 2001
Chapter6 Card and Service Configuration
Frame Service Module Features
Summary of Frame Service Module Features
This section contains a summar y of t he f eat ur es common to all FRSM models. Th e fo ll owi ng
sub-sections also contain summa ries of the features unique to e ach t ype of FRSM.
All FRSMs support:
•Frame Relay-to-ATM Network Interworking (NIW) as defined in FRF.5.
•Frame Relay-to-ATM Service Interwor ki ng ( S I W) w ith o r without translation as i n FR F.8.
•Frame Forwarding.
•ATM Frame-UNI.
•Maximum frame sizes of 4510 bytes for Frame Relay and 4096 bytes for ATM-FUNI.
•Per-virtual-circuit (VC) queuin g in the ingress direction (toward the cell bus). Traffic arriving at the
network on a connection has a dynami cal ly as si gn ed buffer at t he e nt ra nc e to th e sh el f. Buffer size
depends on the amount of traffic and the s er vice -level agreement (SLA).
•Advanced buffer management. When a frame arrives, the depth of the queue for the LCN is
compared against the peak queu e d ep th sc aled down by a specified factor. The scale-d own fa cto r
depends on the amount of congestion in the free bu ffer pool. As the free buffer pool begins to empty,
the scale-down factor is in crea se d, pre v e nting an exc es si ve nu mber of bu f fe rs f rom be ing h el d up b y
any single LCN.
•Multiple, priority-level queuing to support class of service on the egress. The FRSM services egress
queues according to a weighted priority. The priority depends on the percentage of logical port
bandwidth needed by all connections of a particular type on a port. The FRSM supports a:
–
High-priority queue
–
Real-time Variable Bit Rate (rt-VBR) queue
–
Common queue for non-real-time Variable Bit Rate (nrt-VBR) and ABR connections
–
UBR queue
•Initial burst per channel. After a period of silence, the FRSM sends a configurable number of bytes
at a peak service rate.
•The ForeSight option (except on MGX-FRSM-HS1/B). This Cisco mechanism for managing
congestion and optimizing bandwidth monitors the utilization of ATM t r unks. It proactively adjusts
the bandwidth for connections to avoid queuing delays and cell discards.
•Consolidated Link L a yer Management (C LL M ) , an out-of-band me c hanism to transpor t
congestion-related informat ion to the far end .
•Dual leaky bucket policing. Within the basic parameters such as committed burst , excess burst, and
CIR, incoming frames go into two buckets: those to be checked for c ompliance with the committed
burst rate and those to b e c hecked for complianc e w i th the excess burst rate . Frames that overflow
the first bucket go into the second bucket. Th e bu cke ts “lea k” by a certain amount to allow for
policing without disru p tio n o r de lay of service.
•Standards-based management tools. Each FRSM supports SNMP, TFTP for configuration and
statistics collection, and a c om m an d lin e in ter fa ce. Th e Cisco WAN Manager application provides
full graphical user interface support for connection management. The CiscoView application
provides equipment m a na gement.
•MGX 8800 series network manageme nt func tions, inclu ding image do wnl oad, c onfigu rati on uploa d,
statistics, telnet, UI, SNMP, trap, and M I Bs.
•OAM features: LMI and Enhanced LMI (ANNEX A, ANNEX D, Strata LMI).