Where to Run LANE Services

One of the first questions facing most implementers of LANE is "Where should I locate my three server components (LECS, LES, and BUS)?"

Because the LECS function is a very low-CPU function, you have a fair amount of latitude in terms of where you place the LECS. The main criterion is to pick a device with high availability. Some network designers argue that the best location is an ATM

switch because it provides a centrally-located database. However, other designers argue that during a partial network outage, the ATM switch has its hands full just trying to build new SVCs. To further burden it with handling LECS duties hampers network resiliency. I generally try to locate the LECS in a Catalyst LANE module. However, a platform such as a 7500 router can also be a good choice.

The LES function requires more CPU effort than the LECS function, but it is generally not a burdensome amount. On the other hand, the BUS does require a tremendous amount of effort—it must be able to handle all broadcasts and all multicasts on the network while also supporting unicast traffic until the Flush process can occur. Because Cisco requires the LES to be co-located with the BUS, the BUS becomes the component that must be carefully positioned. In practice, the Catalyst 5000 currently provides the best BUS performance of the Cisco product line (as well as having top performance within the industry). Table 9-5 shows the BUS performance for various Cisco ATM devices expressed in kilopackets (thousands of packets) per second. When released, the Catalyst 6000 OC-12 ATM module is expected to have performance comparable to that of the Catalyst 5000 OC-12 module.

Table 9-5. BUS Performance by Hardware Platform (in Kilopackets per Second)

Platform

KPPS

Catalyst 5000 OC-12 LANE Module

500 +

Catalyst 5000 OC-3 LANE Module

125

ATM PA (in 7500 and 7200)

70

Catalyst 3000

50

4700 NMP-1A

41

LS1010

30

7000 AIP

Note

Although Catalyst LANE modules provide the highest throughput in Cisco's products line, routers with very powerful CPUs (such as the 7500 RSP4) can provide faster recovery during network failover (the additional CPU capacity allows them to build VCs more quickly). In general, this is less important than the throughput numbers presented in Table 9-5.

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