Nortel Web OS 10.0, Application Manual

Page: 217 / 482

212777-A, February 2002
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C
HAPTER
9
Virtual Matrix Architecture
Virtual Matrix Architecture (VMA) is a hybrid architecture that takes full advantage of the dis-
tributed processing capability in Alteon Web switches. With VMA, the switch makes optimal
use of system resources by distributing the workload to multiple processors, thereby improving
switch performance and increasing session capacity. VMA also removes the topology con-
straints introduced by using Direct Access Mode (DAM).
The number of concurrent sessions per switch, with VMA enabled, is given below:
n
AD4 and A184: 512K
n
AD3 and A180E: 336K
n
AD2: 256K
For better switch performance and higher session capacities, it is recommended that you
enable VMA, especially when using Bandwidth Management and Content Intelligent Switch-
ing for multiple frames processing (up to 4500 bytes).
Proxy IP Addresses and VMA
By default, VMA is enabled on the Web switch (
/cfg/slb/adv/matrix
). If you are
upgrading to Web OS from a previous release, however, VMA will be initially disabled if a
proxy IP address is configured for any port on the switch. VMA requires that if any port is con-
figured with a proxy IP address, then all ports (except port 9) must be configured with a unique
proxy IP address prior to enabling VMA.
With VMA, the concept of a per-port session table doesn’t apply; instead, there is a global ses-
sion table. To identify which processor should process responses to proxied requests, a unique
proxy IP address must be configured on each port (except port 9). The action of the unused
proxy IP addresses can be disabled using
/cfg/slb/port x/proxy dis
.