Avaya M-ACCF/SF manual Data VCCs

Chapter 1 Overview

Table 1.1	Control VCCs (Continued)
VCC Name		From/To	Information carried	Initialized	Duration
				by
Control-		LES==>LEC	LES distributes	LES	Membership
distribute			control traffic to		of LEC in
			LECs, including		ELAN
			LE_ARP information

Data VCCs

Data VCCs carry data frames between LECs and between a LEC and the BUS. Unicast data is normally sent from one LEC to another LEC by data-directVCCs. Data direct VCCs are set up dynamically in a SVC environment by a transmitting LEC after ascertaining the ATM LEC destination address for the packet to be transmitted. Once established, a data-direct VCC remains in place for transmission of subsequent traffic between the two LECs. However, a data direct VCC that remains unused for VCC-Timeout-periodis released by the LEC.

Amulticast data VCC pair (multicast-sendand multicast-forward) are established between a LEC and the BUS in order to allow the LEC to send and receive multicast data. In addition, initial unicast data (data whose LEC destination has not yet been ascertained by the transmitting LEC) is sent on the multicast-send VCC to the BUS which forwards it to all other LECs in the same ELAN. Characteristics of the data VCCs are summarized in the following table:

Table 1.2	Data VCCs
VCC		From/To	Information	Initialize	Duration
Name			carried	d by
Data-		LEC<==>LEC	Point-to-point	LEC	Established by
direct			Unicast data		need and released
			between LECs		when unused for
					VCC-Timeout-
					period.
Multicast-		LEC<==>BUS	LEC sends	LEC	Membership of
send			multicast and		LEC in ELAN.
			initial unicast
			data to BUS
Multicast-		BUS==>LEC	BUS distributes	BUS	Membership of
forward			data traffic to		LEC in ELAN.
			LECs

6 Avaya M770 M-ACCF/SF ATM Access Modules User’s Guide