Cisco 10000 Series User Manual

6-24
Cisco 10000 Series Router Quality of Service Configuration Guide
OL-7433-09
Chapter 6 Policing Traffic
Data Included in the Policing Rate
Table 6-3 describes what bandwidth is based on for each media type.
Be sure to take into account the framing and cell overhead when specifying a minimum bandwidth for a
class. For example, if you need to commit a rate of 1000 64-byte packets per second and each packet has
4 bytes of framing overhead, instead of using 512 kbps in the bandwidth or police command, use
544
kbps, calculated as follows:
1000 * (64 + 4) * 8 /1000 = 544
A similar scenario for ATM requires 848 kbps because each 64-byte packet requires two cells of
53
bytes.
1000 * 2 * 53 * 8 / 1000 = 848
ATM
(UBR)
Layer 2 framing
Cell overhead
Class-Based Shaping
No ATM cell overhead
No AAL Common Part Convergence
Sublayer (CPCS) pad
ATM
(CBR)
Layer 2 framing
Cell overhead
Class-Based Shaping
No ATM cell overhead
No AAL Common Part Convergence
Sublayer (CPCS) pad
1. The router does not account for flags or Frame Check Sequence (FCS) that the hardware adds or removes.
Table 6-2 Policing Rate Data
Media Data Included Data Excluded
Ta b l e 6-3 Basis for Bandwidth
Media Bandwidth Based On
Frame Relay Fragments
1
1. For Frame Relay networks with link fragmentation and interleaving (LFI) enabled.
Ethernet Bits
ATM variable bit rate (VBR) Sustained cell rate (SCR)
ATM unspecified bit rate (UBR) Peak cell rate (PCR)
ATM constant bit rate (CBR) Peak cell rate (PCR)

Cisco 10000 Series Specifications

General

Brand	Cisco
Model	10000 Series
Category	Network Router
Language	English