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CEF Changing Structures on the Cisco Catalyst 6500 Around the SUP720, 'cisco' Driver 6500 uses CEF, which cannot be handicapped, to provide hardware efficiency. Rather than performing switching within software program because previous Cisco hubs do, the Cisco Driver 6500 works switching in hardware using CEF. You need to understand this particular distinction whenever trouble shooting issues involving the SUP720.

Understanding Software-Based CEF as well as Hardware-Based CEF Hardware-based CEF packet changing harnesses the present information buildings constructed by CEF in software and then stretches the ability to equipment by encoding specific hardware reminiscences along with info that the forwarding ASICs may use in order to quickly transfer packages for enhanced performance. In software-based CEF, the actual router builds the actual Forwarding Information Base (FIB) and adjacency tables in line with the routing as well as Deal with Resolution Protocol (ARP) tables. The actual Catalyst 6500 change shops these details in hardware high-speed table storage and utilizes efficient research algorithms with regard to table lookups. In the Driver 6500, these types of high-speed memory tables are Ternary Content Addressable Storage (TCAM) furniture. TCAM utilizes a mixture of worth matching having the ability to cover up for a particular outcome. In this case, the result is a tip for an entry within the equipment adjacency desk that contains the next-hop Macintosh rewrite info.

The actual SUP720 lists FIB entries within the TCAM table from the the majority of specific to the least specific entry. Consequently, the actual TCAM lists all entries with a subnet mask associated with 32 (web host admittance) for the prefix very first. Once the FIB and adjacency tables in the TCAM are full, the actual SUP720 punts traffic for the unfound destination/entry towards the software-switching motor (route processor, or RP) to become dealt with within software. The actual SUP720 comes with an integrated RP as well as change processor (SP) around the Multilayer Change Function Card Three (MSFC3). The SP deals with typical Coating Two capabilities such as Comprising Tree as well as VLAN Trunking. The RP handles typical Coating Three capabilities such as Improved Inside Entrance Routing Process (EIGRP) as well as routing.

The actual SUP720 also has an insurance policy Feature Greeting card Three (PFC3) to support hardware-based forwarding and features for example redirecting, multicast packet duplication, as well as entry control lists (ACLs). Multiple PFC3s, like the PFC3B and the PFC3BXL, can be found. On a SUP720 with a PFC3BXL, the actual FIB TCAM size and also the adjacency table dimensions are 1 million records. The kind of functions allowed can affect the amount of TCAM entries the SUP720 utilizes to keep information. Each IP version Four (IPv4) location prefix recognized takes one entry within the TCAM. Therefore, the actual PFC3BXL version facilitates a large number of IPv4 paths and adjacencies that can be present in a large enterprise or company system. Nevertheless, with IPv6 and ingress multicast paths, each destination takes 2 entries in the TCAM. Refer to 'cisco'.com for that latest information associated with whether an element influences the total quantity of entries stored in TCAM.

The actual SUP720 forces software CEF info right down to the actual equipment The company, which can handle the actual packet forwarding quicker. The RP around the SUP720 sends the data towards the SP in order to plan the actual TCAM and the equipment The company.

Equipment FIB lookup occurs in line with the longest matching destination prefix. The complement within the hardware FIB in line with the location prefix results adjacency info which has the packet reword info for that appropriate outbound user interface. After that, sending from the box happens to another hop within equipment. Observe that prior to the Cisco Driver 6500 passes the actual box outbound, additionally, it validates protection and excellence of service (QoS) policies to confirm the packet is actually legal and should not end up being fallen instead.

Central and Distributed Changing The actual 'cisco' Driver 6500 supports centralized changing or even distributed changing. Central switching occurs when the switch processor chip around the SUP720 can make sending decisions in equipment. Just about all frames should go through the actual centralized SP motor through the switch material or coach. Bus and crossbar changing modes make use of the central SP.

With use of the Dispersed Sending Credit cards (DFCs) on the line segments, dispersed switching can happen. Along with dispersed switching, forwarding occurs in your area on the line segments that avoid the central switching motor on the supervisor motor, and packets tend to be submitted straight between two ports or even over the change fabric.

If visitors are ingress on a card that's DFC equipped, the DFC performs the actual equipment switching for that line greeting card. Consequently, you have to look into the hardware CEF entries around the DFC by itself whenever trouble shooting. You should use the show material switching-mode order to check on whether a line card is DFC outfitted. If the output states "DCEF" (indicating distributed CEF [dCEF]) below changing setting, it features a DFC. 9131252012wed

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