Specifications

AP Overview
RoamAbout Mobility System Software Configuration Guide 9-9
ThisinformationisusedinthefollowingwaywhentheAPattemptstocontactaRoamAbout
Switch:
1. IfItemsAandB(butnotItemC)arespecified,andtheRoamAboutSwitch’sIPaddress ispart
ofthelocalsubnet,thentheAPsendsanARPrequestforitsconfiguredstatic
IPaddress,to
ensurethatitisnotalreadyinuseinthenetwork.TheAPthensendsaFindRASmessageto
UDPport5000attheRoamAboutSwitch’sIPaddress.
•IftheAPreceivesaresponsefromthataddress,itsendsaunicastmessagetothe
RoamAboutSwitch,to
requestanoperationalimage.
•IftheAPdoesnotgetaresponse,thenitsendsaFindRASmessagetoUDPport5000on
thesubnetbroadcastaddress.
•IftheAPreceivesaresponsetothebroadcastFindRASmessage,thentheprocess
continuesusingtheproceduredescribedunderHowan
APContactsaRoamAbout 
Switch(DHCP‐ObtainedAddress),startingwithStep 6onpage 9‐8.
•IfthereisnoresponsetothebroadcastFindRASmessage,thentheprocessskipsto
Step 4onpage 9‐9.
•IftheRoamAboutSwitchisnotpartofthelocalsubnet,thentheAPusesthedefault
routeraddresstocontacttheRoamAboutSwitch.
2. IfItemA, butnotItemBisspecified,thentheAPusesthespecifiedstaticIPconfiguration,and
broadcastsaFindRASmessagetothesubnet.
•IftheAPreceivesaresponsetothebroadcastFindRASmessage,thentheprocess
continuesusing
theproceduredescribedunderHowanAPContactsaRoamAbout
Switch(DHCP‐ObtainedAddress),startingwithStep 6onpage 9‐8.
•IfthereisnoresponsetothebroadcastFindRASmessage,theRoamAboutSwitch
continuesbroadcastingtheFindRASmessageforaperiodoftime.Ifstillnoresponseis
received,
thentheprocessskipstoStep 4onpage 9‐9.
3. IfItemsAandCarespecified,theAPsendsaDNSrequesttoresolvethefullyqualified
domainnameoftheRoamAboutSwitch.IftheDNSserverisnotonthelocalsubnet,theAP
usesthedefaultrouteraddressto
contacttheDNSserver.
•IfthereisnoresponsefromtheDNSserver,thentheprocessskipstoStep 4onpage 9‐9
•IfthereisaresponsefromtheDNSserver,thentheAPsendsaFindRASmessagetothe
RoamAboutSwitch.
•IfaresponseisreceivedfromtheRoamAbout
Switch,thentheAPsendsaunicast
messagetotheRoamAboutSwitch,torequestanoperationalimage.
•IfaresponseisnotreceivedfromtheRoamAboutSwitch,thentheprocessskipsto
Step 4onpage 9‐9.
4. IftheAPcannotreachtheRoamAboutSwitchusingthestaticIPaddressinformation,then
the
APattemptstobootusingthedefaultbootprocess;thatis,bycontactingaDHCPserver,as
describedin“HowanAPObtainsanIPAddressthroughDHCP”onpage 9‐6.Ifthedefault
APbootprocessdoesnotsucceed,thentheAPagainattemptstobootusingits
statically
configuredIPinformation.TheAPalternatesbetweenthetwobootprocessesuntilthe
RoamAboutSwitchiscontacted.
IfthedefaultAPbootprocessissuccessful,buttheDHCPresponsedoesnotincludeaDNS
serveraddress,thentheIPaddressoftheDNSserverspecifiedaspartofItem
Cisused.