Cisco Systems 8600 Series manual Port VSI Partition LCN Allocation Elements

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Details of More Rigorous Allocations

More rigorous allocations are possible when default values are not applicable. For example, the LCN allocations for a port group must satisfy the following limit:

sum ( a (x) ) + sum ( n1 (x) ) +t*270 <= g

In this expression, “a (x)” represents AutoRoute LCNs, “n1 (x)” represents the guaranteed minimum number of VSI LCNs, “t” is the number of ports in the port group that are configured as AutoRoute trunks, and “g” is the total number of LCNs available to the port group. Figure 9-10shows the relationship of these elements.

The “270” value reflects the number of LCNs which are reserved on each AutoRoute trunk for internal purposes. If the port is configured in port rather than trunk mode, “t” = 0, and t*270 drops out of the expression.

Figure 9-10 Port VSI Partition LCN Allocation Elements

g = port group common pool, e.g., 8192

sum n(x)

sum a(x)

		Port group LCNs
	Unallocated LCNs in common pool "g"	(e.g. 8192)
z =	available on a FIFO basis to port VSI
	partitions that exceed their configured
	guaranteed minimum LCN settings.

t*270 12144

Note Tag switching can operate on a BXM card configured for either trunk (network) or port (service) mode. If a BXM card is configured for port (service) mode, all ports on the card are configured in port (service) mode. If a BXM card is configured for trunk (network) mode, all ports on the card are configured for trunk (network) mode. When the card is configured for trunk mode, the trunks reserve some connection bandwidth.

In the following expression, “z1“ equals the number of unallocated LCNs in the common pool of LCNs available for use by the port VSI partitions. The value of “z1“ is the number of LCNs available after subtracting the AutoRoute LCNs [sum ( a (x) ], VSI LCNs [sum (n1 (x) )], and LCNs for trunk use [t*270] from the total number of LCNs “g” available at the port. For a BXM card with ports configured in “port” mode, “t” = 0.

z1 = (g - sum ( a(x) ) - sum ( n1(x) -t*270)

Tag Switching 9-39