TABLE OF CONTENTS An example of the single control card + multiple line card architecture is shown in Figure 8.4. There is one control card, with four line cards and a switch fabric card. The switch fabric and the line cards are connected through high-speed serial links. The control card and the line card can be connected by PCI or Fast Ethernet. The latter is sometimes known as the internal Ethernet or Ethernet on the backplane. The control card to line card interface is used for messages that need to be processed by the control card s processor(s) and for messages originated by the control card to be sent to the physical ports. The bandwidth requirement on this control card to line card interface is not as high as the line card to switch fabric interface. However, when systems with a large number of line cards are built, the traffic on this interface can become an issue. System designers often address this by using a high-speed switched connection like Switched Gigabit Ethernet or Infiniband.
Line card to line card data transfer is through the switch fabric. The switch fabric card provides the switching function for the payload sent by the line cards. In the IPS, if a frame is forwarded from Port 1 of Line Card 1 to Port 3 of Line Card 2, it is sent on the serial link from Line Card 1 to the Switch Card and then from the Switch Card to...
