Cisco Systems IGX 8400 ,

4-12 Cisco IGX 8400 Series Reference

Universal Switching Module Enhanced

To determine how many UBUs are necessary, use the values for average bandwidth used in the

following formula:

In most circumstances, the fps and cps valuesfrom average bandwidth used are sufﬁcient. The peak

bandwidth used values are primarily informational.

The information in Table4-5 provides the ranges for the interface type. Note that, if you do the math

according to the formula, you see that the value in the cells-alone column of Table4-5 equals the

result of adding half the FastPacket value to the cell value in the cells plus FastPackets column.

When you use dspbusbw,a yes/no prompt asks if you want ﬁrmware to retrieve the usage values. If

you enter a “y,” the UXM-E reads—then clears—its registers and thus restarts statistics gathering.

If you enter an “n,” switch software displays the current values that reside in control card memory

(on the NPM). The values in memory come from the last update from the UXM-E.

TheUXM-E can support trunking across a public ATM network so both virtual channel connections

(VCCs) and virtual path connections (VPCs) traverse a single virtual path trunk. This feature lets

you map multiple trunks to a single port of an NNI. The NNI connects to either a public or private

ATMnetwork. The virtual trunk package is a lower-cost alternativeto leased circuits but still has the

full set of Cisco ATM trafﬁc management capabilities. This application requires two UXM-Es and

a clock from an external source. The rates can be OC-3/STM-1, T3/E3, or T1/E1.

Figure 4-4 UXM-Es Conﬁgured for a Public ATM Network

Note the following characteristics of this form of trunking across a public network:

•The trunk cannot provide the a clock for transport across the public network.

•This feature does not support VPC connections across the public network.

•The node number at each endpoint must be 17 or higher.

Refer to Figure 4-3 as you read the steps for the following example set-up:

Step 1 Connect a cable between each of the following:

•8.1 and 9.1

•8.2 and 9.2

UXM-E

trunk UXM-E

port

slot 8 slot 9

1 Cable 1

2 2

3 3

4Public

network

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