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This soft copy for use by IBM employees only.
prevent interworking with the IBM ATM switches. This function solves this
problem by allowing the the network administrator to set the VPC/VCC range
on a given ATM port on the ATM switch, thereby enabling the interworking
with non-compliant devices. For example, you can restrict the VPI value
equal to 0 and VCI value comprised between 0 and 63 by specifying 0/6 as
the VPI/VCI.
Note
If you change the VPI/VCI range for the SSI or NNI port, you
must
specify
the same value on both ends.
•
ABR Flow Control Support
On the ATM 12-port 25 Mbps UTP Concentrator module, the ATM 3-port 155
Mbps LAN Concentration module, and on the 12-port 25 Mbps base unit, the
end user can add the ATM Forum-compliant
available bit rate (ABR)
flow
control through Explicit Forward Congestion Notification Indication (EFCI)
marking. When congestion occurs due to excessive traffic flow, the IBM 8285
and 8260 modules can now mark the EFCI bit in the ATM cells to indicate a
congestion condition asking the destination station to notify the source
device to reduce its traffic.
•
Increase Buffer Size
When multiple ATM sources try to send traffic over one link (for instance the
one to which a server is attached), using UBR or ABR class of service,
congestion conditions might occur because the aggregate traffic exceeds the
capacity of the LAN traffic over ATM. By having a larger buffer size (8,000
cells) the A12-MB25 and A3-MB155 modules are able to absorb bursts of
traffic of longer duration, thereby delaying the trigger of the congestion
control mechanism, such as Early Packet Discard. This improves the overall
response time and relieves end systems from extra frame retransmissions.
•
PVC Multipoint Support
In addition to the existing support of point-to-multipoint SVCs, this introduces
the smart PVC point-to-multipoint function. Point-to-multipoint trees can be
defined now with either fixed permanent virtual paths (PVPs) or fixed
permanent virtual channels (PVCs). You only need to define the parameters
(VP or VP/VC values) for the root of the tree and the leaves, without any
definition for intermediate switches. In case of failure on these intermediate
switches, the connections are automatically re-established.
•
New 8260 ATM Modules Support
In addition to the control point level V1.2, this level supports the new IBM
8260 ATM modules as follows:
− ATM 3-Port 155 Mbps LAN Concentration Module
•
MIB Enhancement (MIB 1.6)
The IBM private MIB for the IBM 8285 is enhanced corresponding to the
other announcements.
32 ATM Workgroup Solutions: Implementing the 8285 ATM Switch