Table Of Contents
Bandwidth Information for Cisco 7304 Routers
The following guidelines and restrictions are related to overall bandwidth limitations and should be considered when installing hardware into the Cisco 7304 router slots:
•Only one OC-48 Line Card can be used in a Cisco 7304 router regardless of processor.
•No more than 3 Gigabit Ethernet SPA interfaces should be used at any given time.
•In general, the Gigabit Ethernet interfaces, the OC-12 interfaces, and the OC-48 interface consume significantly more bandwidth than other Cisco 7304 interfaces. If you are installing any of these line cards or SPAs, please pay particular attention to the aggregate bandwidth of the ports on your router.
The connections from each of the router slots converge into a 4 Gbps link before they enter the forwarding engine (see Figure 1 for a graphic illustration). Although the physical bandwidth of the link entering the forwarding engine is 4Gbps, the actual throughput will be slightly less due to internal overheads. We, therefore, recommend not exceeding the 4Gbps of bandwidth. If bandwidth limits are exceeded, some network traffic will arbitrarily be dropped when the router is oversubscribed. Since these drops are arbitrary, routing updates, keepalives, and other critical traffic can be dropped.
Cisco Systems strongly recommends configuring your Cisco 7304 router to avoid oversubscribing your router. An error message stating that your router is over its maximum bandwidth is displayed the moment a piece of hardware that could oversubscribe the router is installed. It is important to remember, however, that the amount of traffic traversing the router determines whether traffic is dropped. The error message is simply a warning informing you that, if all ports on all the installed line cards, port adapters, and shared port adapters are used to full capacity, the router will be oversubscribed and packets will be lost. If some ports are installed on the router and are not being used, and the overall capacity of network traffic never exceeds the maximum allowable bandwidth for your processor, your router will not encounter packet drops due to bandwidth oversubscription.
Table 1 provide the maximum allowable bandwidth per processor, and Table 2 provides the amount of bandwidth each port on particular line card can consume at any given time. Table 3 provides the amount of bandwidth consumed by port adapters installed using the PCI Port Adapter Carrier Card. It is important to note that bandwidth consumed on ports directly on the processors does not count against the maximum allowable bandwidth as stated in Table 1.
The bandwidth that a particular piece of hardware in a Cisco 7304 router slot consumes when fully used can also be found by entering the show diag command.
Table 1 Cisco 7304 Processor and Allowable Bandwidth
Processor Maximum Allowable Bandwidth 1
3.2 Gbps (3,200,000 kbps)
3.2 Gbps (3,200,000 kbps)
4.0 Gbps (4,000,000 kbps)
1 Bandwidth consumed by ports on the processors are not counted against the aggregate system bandwidth. The aggregate bandwidths given in this table are for ports on line cards, port adapter, and shared port adapters installed in the Cisco 7304 Router slots.
Table 2 Cisco 7304 Bandwidth
Table 3 Cisco 7304 Port Adapter Bandwidth
Figure 1 Graphical Illustration of Cisco 7304 Backplane