Catalyst 4500
From Internetworkpro
| Catalyst 4500 | |||
 Cisco Catalyst 4500 | |||
| Manufacturer: | Cisco Systems | ||
|---|---|---|---|
| Design: | Modular, chassis based | ||
| Positioning: | Access, Limited Aggregation | ||
| Throughput: | 30 mpps | ||
| Switch Fabric: | 6Gbps traces to each slot | ||
| Max Ports: | 8x48 (384) + 2x10GE | ||
This article is about the Catalyst 4500. For information on its weaknesses see criticism of the Catalyst 4500.
The Catalyst 4500 is a modular chassis mid-range switch. Its target application is for wiring closets and distribution blocks.
[edit] Architecture
The 4500 uses a shared-memory architecture, where the supervisor maintains all intelligence and processing. The line cards are little more than physical converters from the ingress media to the internal architecture.
At its core, the 4500 comprises of either a single or dual supervisors (depending on the chassis) with six 1gb traces to each line card (see above). All queuing, switching and processing is then performed on the active supervisor.
The primary limitation of this design is that if any ingress traffic on a line card group exceeds 1gb, the traffic is dropped. This is because all queuing and buffering occurs centrally on the supervisor - which we cannot get to. In situations where high throughput at low latencies is required, the 4500 is generally not positioned (and thus is a mid-range switch). For high-performance applications, the Catalyst 4900 is recommended.
[edit] Passive Backplane
Unlike the 6500, the backplane is truly 100% passive on the 4500 and the line cards are largely void of intelligence, giving them a very high MTBF and relatively low cost. Additionally, the 4500 scales based on the supervisor and not based on the line cards, so new features can be implemented quickly on older chassis by simply upgrading the supervisor.
[edit] 3750 vs. 4500
The 3750 and in particular the 3750-E has often been compared to the 4500 for positioning, mainly due to their enhanced backplane speeds and (in the case of the E series) non-blocking 10GE ports. Generally, the 4500 scales to larger port densities at a better price and some key features, such as Netflow, is available on the 4500 and not the desktop switches. Conversely, higher 15.4W PoE and 10GE density can be achieved on a stacked 3750-E architecture, as well as better queuing and link utilisation.
