packet size. This would only enable a wide node to handle approximately 7.5 MB/s of IP traffic.
Since Ascend’s business depends on keeping pace with networking technology, they already support the major interfaces today. The 9077 will be able to take advantage of any new interfaces that are developed in the future as well, with no further development time or money expended.
With some interfaces requiring up to 5 slots, even a wide node can run out of available slots. This forces additional nodes to be added even if there are no performance limitations in the current configuration.
Since there are no hot plug capabilities with an SP node, any failure means downtime on all interfaces configured in that node, and at times a lengthy maintenance procedure. Redundancy is not built into the SP node’s architecture.
These facts are illustrated in Figure 2:
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| SP Node | 9077 | ||
Bus | Shared | |||||
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| 1 MCA per thin node | 250 ns path setup | ||
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| 2 MCA per wide node |
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Route Table | Centralized | Independent lookups per card | ||||
| Cache,Software Based | Hardware based, <2.5 µs | ||||
| Cache hits <50% typical | 150,000 route capacity per card | ||||
Scalability | Single port per card | High per card port density | ||||
| Single CPU | Per card | ||||
| Limited by shared bus |
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| Processors | ||
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| Route Tables |
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| Lookup engines |
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| Each card has dedicated bandwidth | ||
Throughput | 5000 pps | Up to 130,000 pps | ||||
| 30 MB/s per thin node | 100 MB/s per card slot, full duplex | ||||
| 65 MB/s per wide node |
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Support | No support for: | Support for: | ||||
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| HSSI |
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| multiple SP Switch interfaces |
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| ATM OC12 |
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| Sonet |
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| HIPPI |
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| Multiple SP Switch Adapters |
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| Protocols |
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Figure 2. Functional Comparison
Router Node 7
