Data Vccs - 3Com CoreBuilder 7000 Operation Manual

142 C 7: LAN E
HAPTER
Table 36 Control VCCs
VCC Name
Configuration
Control-direct
Control-distribute

Data VCCs

Table 37 Data VCCs
VCC Name From
Data-direct LEC
Multicast-send LEC
Multicast-forward BUS
V 1.0
MULATION ERSIONS AND
From To Information carried
LEC LECS LEC requests and receives
configuration information
from LECS, including LES
address
LEC LES LEC sends and receives
controls from LES, including
LE_ARP information
LES LEC LES distributes control traffic
to LECs, including LE_ARP
information
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-direct VCCs. 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-period is released by the LEC.
A multicast data VCC pair (multicast-send and multicast-forward) is
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:
To Information carried
LEC Point-to-point Unicast data
between LECs
BUS LEC sends multicast and
initial unicast data to BUS
LEC BUS distributes data traffic to
LECs
Figure 46 illustrates the VCCs active among LAN Emulation Components.
2.0
Initialized by
LEC
LEC
LES
Initialized by Duration
LEC
LEC
BUS
Duration
While needed
Membership of
LEC in ELAN
Membership of
LEC in ELAN
Established by need and
released when unused for
.
VCC-Timeout-period
Membership of LEC in
ELAN.
Membership of LEC in
ELAN.