Specifications

Terms and Definitions
December 02, 2010 Page 3 of 5
Priorityqueueing,fromhighprioritytolowpriority,isgiventothefollowingfourtraffic
categories:
1. Networkcontrol–Protocolpacketsnecessaryformaintainingnetworktopologysuchas:
–L2(STP,GVRP,LACP)
–L3(VRRP,OSPF,RIP,BGP,DVMRP,PIM)
–ARP
2. Networkdiscovery–Protocolpacketsusedfordisseminationofnetworkcharacteristicssuch
as
LLDP,CtronDP,andCiscoDP
3. Configureddrop‐precedence–PacketsassociatedwithapolicyrulethatspecifiesaClassof
Servicewithaconfigureddrop‐precedenceoffavored(0),best‐effort(1),orunfavored(2)
4. Best‐effort–Alltrafficthatdoesn’t fallintoany othercategorylistedhere
Network
control,networkdiscovery,andbest‐effortprioritiesarehardcodedandcannotbe
modified.Drop‐precedenceisassignedtoaClassofServiceusingthesetcossettingscommand
andappliedtoapolicyruleusingthesetpolicyrulecommand.Best‐effortistrafficthatis
undefinedwithintheFlex
‐Edgecontext,andthereforebydefinitioncannotbeconfiguredfor
purposesofbackpressureorforwardingpriority.Best‐effortcategorizedtrafficisgiventhelowest
prioritybytheFlex‐Edgemechanism,withtheexceptionofunfavoreddrop‐precedencewhichis
thelowestprioritypossiblewithintheFlex‐Edgemechanism.
Theonlyuser
configurableaspectoftheFlex‐Edgefeatureisdrop‐precedence.Drop‐precedenceis
aCoSsettingsoption.CoSsettingsareassignedtoapolicyrule.InaFlex‐Edgecontext,drop
precedenceislimitedtorulesthatapplytoasingleportandspecifyatrafficclassificationofeither
port
ormac‐source.Foranypacketsmatchingthepolicyrule,youcanassignoneofthree
drop‐precedenceprioritylevels:
•Favored‐Adrop‐precedencevalueof0providesabetterchanceofbeingpassedonforpacket
processingthantrafficcategorizedasbest‐effort.
•Best‐Effort‐Adrop‐precedencevalueof
1providesabest‐effortlevelofprioritywithinthe
Flex‐Edgepriorityscheme.
• Unfavored‐Adrop‐precedencevalueof2providesasomewhatworsechanceofbeingpassed
onforpacketprocessingthantrafficcategorizedasbest‐effort.Thisisthelowestpossible
prioritysettingwithintheFlex‐Edgemechanism.
Terms and Definitions
Table 1liststermsanddefinitionsusedinthislinkFlex‐Edgediscussion.
Note: See the QoS feature Guide for a complete discussion of Class of Service. See the Policy
feature guide for details on how a Class of Service is applied to policy. Enterasys feature guides can
be accessed on the Enterasys Support public website:
http://secure.enterasys.com/support/manuals/
Table 1 Flex-Edge Terms and Definitions
Term Definition
CoS Class of Service.
drop-precedence A CoS setting assigned to a policy rule, specifing a traffic classification to either a
port or mac-source of favored, best-effort, or unfavored.