Specifications

TWCB Overview
April 16, 2009 Page 6 of 14
•Placetheweb‐cacheinservice.Atleastonecacheservermustbeinservicebeforeyoucan
placeaweb‐cacheinservice.
The Outbound Interface
Theoutboundinterfaceistypicallyaninterfacethatconnectstotheinternet.Itistheinterfacethat
willbeusedforredirectingwebobjectsfromthehostwebsitetothecacheserver.Withinthe
interfaceconfigurationcommandmode,youcanconfigurethisinterfacetoredirectoutbound
HTTPtraffictothe
web‐cache.Uptothreeoutboundinterfacescanberedirectedtotheweb‐cache.
The Switch and Router
WithinswitchconfigurationcommandmodeyoucansetTWCBrelatedrouterlimits.
RouterlimitscanbesetandresetforthenumberofTWCBbindings,thesizeoftheTWCBcache,
andthenumberofweb‐cachesthatcanbeconfigured.
Bindingsandcachesizeusememoryresources.Amaximumof
32000bindingsandcachesizeof
10000aresharedbysuchapplicationsasTWCB,NAT,andLSNATonafirstcome,firstserved
basis.BysettingthemaximumnumberofbindingsandcachesizeusedbyTWCBtoavaluelower
thanthemaximumvalue,youassurethattheremaining
bindingswillbeavailableforusebyother
applications.
Whenresettingrouterlimitstothedefaultvalues,ifyoudonotspecifyaparameter,youwillreset 
routerlimitsforallTWCB,NAT,andLSNATparameters.
WithinrouterconfigurationcommandmodeyoucanclearTWCBstatistics.
The TWCB Binding
ATWCBflowhasthreedevicesassociatedwithit:aclientthatinitiatesaservicerequest,the
destinationdevicethatrespondstotheservicerequest,andacacheserverthatcachestheresponse
data.EachactiveTWCBflowhasabindingresourceassociatedwithit.Eachflowisbasedupon
the
followingcriteria:
•SourceIPAddress‐TheclientIPaddress
• DestinationIPAddress‐TheIPaddressofthedestinationdevice
• DestinationPort‐TheDestinationDevicePort
•CacheServerIPAddress‐TheIPaddressofthecacheserver
UsetheshowiptwcbconnscommandtodisplayactiveTWCBflowsforthisdevice.
Note: The maximum number of bindings and cache available should only be modified to assure
availability to functionalities that share these resources such as TWCB, NAT and LSNAT. It is
recommended that you consult with Enterasys customer support before modifying these parameter
values.