network protocols handbook.pdf

157Protocols GuideWAN - ATM ProtocolsQUIRY, sent by the user or the network to solicita STATUS message.4. Point-to-Multipoint messages: such as ADDPARTY, which adds a party to an existingconnection. ADD PARTY ACKNOWLEDGE,which acknowledges a successful ADD PAR-TY. ADD PARTY REJECT, which indicatesan unsuccessful ADD PARTY. DROP PARTY,which drops a party from an existing pointto-multipointconnection. DROP PARTY AC-KNOWLEDGE, which acknowledges a successfulDROP PARTY.• Message length - The length of the contents of amessage.• Information Elements - There are several types ofinformation elements. Some may appear only oncein the message; others may appear more than once.Depending on the message type, some informationelements are mandatory and some are optional. Theorder of the information elements does not matter tothe signalling protocol. The information elements inUNI 3.0 are listed in the following table:CauseIEDescriptionGives the reason for certain messages.For example, the Cause IE is part of therelease message, indicating why the callwas released.Call state Indicates the current state of the call. 1Endpoint referenceEndpoint stateAAL parametersATM user cellrateConnectionidentifierQuality of ServiceparameterBroadband highlayerinformationBroadbandbearer capacityBroadband lowlayerinformationBroadband lockingshiftBroadband nonlockingshiftBroadband sendingcompleteIdentifies individual endpoints in a point-tomultipointcall.Indicates the state of an endpoint in apoint-to-multipoint call.Includes requested AAL type and other AALparameters.Max.No.Specifies traffic parameters. 1Identifies the ATM connection and gives theVPI and VCI values.Indicates the required Quality of Serviceclass for the connection.Gives information about the high-layerprotocols for compatibility purposes.Requests a service from the network (suchas CBR or VBR link, point-to-point andpoint-to-multipoint link).Checks compatibility with layer 2 and 3protocols.Indicates a new active codeset. -Indicates a temporary codeset shift. -Indicates the competition of sending thecalled party number.2111111131Broadband repeatindicatorCalling partynumberCalling partysubaddressCalled partynumberCalled partysubaddressTransit networkselectionRestart indicatorIndicates how IEs which are repeated inthe message should be handled.Origin of the call. 1Subaddress of calling party. 1Destination of the call. 1Subaddress of the called party. 1Identifies one requested transit network. 1Identifies which facilities should be restarted(e.g., one VC, all VCs).Related protocolsATM, AAL0-AAL5, LAN Emulation (LANE), CES, PNNI, MPOA,NNI and Q.2931.Sponsor SourceThe ATM protocols are based on standards developed by theITU.http://www.atmforum.com/standards/approved.htmlATM Forum approved specificationsReferencehttp://www.atmforum.com/standards/approved.htmlATM Forum approved specificationshttp://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/atm.htmATM Overview11