Specifications

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Terminology

Aggregate A type of Policer (see Policing) applied to ALL traffic matching a particular traffic class

ASIC Application Specific Integrated Circuit is a purpose built chipset designed to perform a specific

function in hardware

CatOS Catalyst Operating System is one of two operating system options available for the Catalyst

6500 platform. Originally derived from the Catalyst 5000 code base.

Cisco IOS Cisco IOS is the second of two Operating Systems available for the Cat6500. Code Base

derived from router IOS and provides single OS image for L2 and L3 subsystems and single

configuration file.

CEF Cisco Express Forwarding is a technique whereby a forwarding information base is computed

from the routing tables and used by the PFC to switch all L3 traffic

Classification Process of identifying a frame based on specific Layer 2, 3 and 4 fields in the header

CoS Class of Service—This is a Cisco term used to refer to the 802.1p specification—if refers to the

3 bits in an Ethernet header that indicate the priority of an Ethernet frame

dCEF Distributed version of Cisco Express Forwarding used by the DFC or DFC3x in combination with

the PFC2 or PFC3x

DFC Distributed Forwarding Card is a combo daughter card comprising a MSFC and PFC used by a

fabric enabled Cat6500 line card to perform distributed switching

DSCP Differentiated Services Code Point is the six most significant bits in the ToS byte, and is used to

indicate the priority of an IP Packet. Not to be confused with the internal DSCP (see below).

Frame Term used to define a piece of data with a layer 2 header. An example would be an Ethernet

frame.

Flow A unidirectional flow of traffic from a source host to a destination host. Most TCP/IP connections

use 2 flows, one for sending data and one for receiving data.

Internal DSCP An internal priority assigned to the frame by the PFC as it transits the switch. It is derived from

an existing CoS or ToS setting and is used to reset CoS or ToS as the frame exits the switch.

IP Precedence The three most significant bits in the ToS field in the IPv4 header used to indicate the priority of

an IP Packet

Microflow A type of Policer (see policing) applied on a per flow-basis for traffic coming into a port or a

VLAN

MSFC Multilayer Switch Feature Card is the Layer 3 switching engine that sites on the Catalyst

Supervisor as a daughter card.

MSFC1 Multilayer Switch Feature Card found on a Supervisor 1 or Supervisor 1A

MSFC2 Multilayer Switch Feature Card found on a Supervisor 1A or Supervisor 2

MSFC3 Multilayer Switch Feature Card found on all Supervisor 720 models

MSFC4 Multilayer Switch Feature Card found on all Supervisor 720-10GE models

Packet Term used to define a piece of data with a layer 3 header. An example would be an IP packet.