Lucent Technologies P550 - Manual (Page 28)

Cajun P550 Switch Overview
1-8 Cajun P550/P220 Switch Operation Guide
Consequently, when you connect a Cajun switch to the network, it begins to receive
frames from the network and builds a master routing table in the supervisor module and
forwarding tables in each media module based on those frames.
This process creates three distinct results:
❒ All known (learned) traffic from Layer 3 modules that requires routing is routed
directly in hardware by the Layer 3 media module without a need to traverse the
switching fabric to get to the supervisor module’s software routing function.
❒ All unknown (not learned) traffic from Layer 3 modules must first be sent to the
Layer 3 supervisor module, where information on the frame is added to the
supervisor module’s master routing table and added to the appropriate address
caches of Layer 3 media modules.
❒ Since Layer 2 modules have no routing capability, packets that are received by a
Layer 2 module and require routing are routed by sending the packet to the Layer
3 supervisor module. The routing engine on the supervisor module then performs
the routing operation for the Layer 2 modules and sends the packet back through
the switching fabric to the destination port.
Figure 1-4 shows a conceptual example of how traffic is routed in a Cajun switch.
Figure 1-4. Layer 2/3 Routing with Cajun Switch
Virtual Bridging Functions
The switch design supports:
❒ Up to 24,000 MAC addresses in the switch address forwarding table - This feature
allows the switch to store forwarding information for hosts in very large networks.
❒ Segmented address tables qualified by address and VLAN membership - This
feature allows the same host to appear on different VLANs on different ports.
Between L2 I/O Modules Between L3 I/O Modules Between L2 and L3 I/O Modul
B e t w e e n L 2 I / O M o d u l e s
L 2 / L 3
Supervisor
L 2 I / O M o d u l e
L 2 / L 3 I / O M o d u l e
B e t w e e n L 3 I / O M o d u l e s
L 2 / L 3
Supervisor
L 2 / L 3 I / O M o d u l e
L 2 / L 3 I / O M o d u l e
B e t w e e n L 2 a n d L 3 I / O M o d u l e s
L 2 / L 3
S u p e r v i s o r
L 2 I / O M o d u l e
L 2 / L 3 I / O M o d u l e