利用者:Network101

CEF Switching Structures on the 'cisco' Catalyst 6500 On the SUP720, 'cisco' Driver 6500 utilizes CEF, that cannot be disabled, to supply equipment efficiency. Rather than carrying out changing within software program because prior Cisco routers did, the actual 'cisco' Catalyst 6500 performs switching within equipment utilizing CEF. You must know this particular distinction when troubleshooting problems involving a SUP720.

Knowing Software-Based CEF and Hardware-Based CEF Hardware-based CEF box changing harnesses the existing information buildings built through CEF within software and then extends the capability in order to hardware through programming specific equipment reminiscences with info that the sending The company may use to rapidly transfer packets with regard to enhanced overall performance. Within software-based CEF, the modem develops the actual Sending Info Foundation (FIB) as well as adjacency tables based on the redirecting and Address Resolution Process (ARP) furniture. The Catalyst 6500 change stores these details in hardware high-speed table memory as well as uses effective search algorithms with regard to desk lookups. Within the Catalyst 6500, these high-speed memory tables tend to be Ternary Content Addressable Storage (TCAM) furniture. TCAM uses a mixture of value matching having the ability to mask for the result. In this instance, the result is the tip for an entry in the hardware adjacency desk that contains the next-hop MAC reword information.

The actual SUP720 lists FIB entries within the TCAM desk in the the majority of specific towards the minimum specific admittance. Consequently, the actual TCAM lists just about all entries with a subnet cover up associated with Thirty-two (web host admittance) for the prefix first. Once the FIB and adjacency furniture within the TCAM tend to be complete, the actual SUP720 punts traffic for the unfound destination/entry to the software-switching engine (route processor, or RP) to be dealt with within software program. The actual SUP720 has an incorporated RP as well as change processor (SP) around the Multilayer Change Feature Card Three (MSFC3). The actual SP handles typical Coating Two functions such as Comprising Tree as well as VLAN Trunking. The actual RP deals with common Coating 3 functions for example Improved Inside Entrance Routing Process (EIGRP) and redirecting.

The SUP720 also has a Policy Function Card Three (PFC3) to aid hardware-based sending and features for example redirecting, multicast packet duplication, as well as entry control listings (ACLs). Several PFC3s, such as the PFC3B and also the PFC3BXL, are available. On the SUP720 with a PFC3BXL, the actual FIB TCAM size and the adjacency table dimensions are 1 million records. The type of functions allowed can impact the number of TCAM entries the SUP720 utilizes to store information. Every IP version Four (IPv4) destination prefix known takes 1 entry within the TCAM. Consequently, the PFC3BXL version supports a lot of IPv4 routes and adjacencies that can be present in a large business or even service provider system. However, along with IPv6 and ingress multicast routes, each destination takes two records in the TCAM. Make reference to 'cisco'.org for the newest info related to regardless of whether an element influences the entire number of entries kept in TCAM.

The actual SUP720 pushes software CEF info down to the equipment ASICs, which can manage the actual packet forwarding quicker. The actual RP on the SUP720 sends the data towards the SP to plan the actual TCAM and also the hardware ASICs.

Equipment FIB lookup occurs based on the longest coordinating destination prefix. A complement in the hardware FIB based on the location prefix results adjacency information that contains the actual box rewrite information for the appropriate outbound user interface. Then, forwarding of the packet happens to another jump in equipment. Note that prior to the 'cisco' Driver 6500 goes by the actual box outgoing, it also validates security and quality of service (QoS) guidelines to verify the packet is lawful and should not end up being fallen rather.

Central and Distributed Changing The 'cisco' Driver 6500 supports central changing or distributed switching. Centralized changing occurs when the change processor on the SUP720 can make forwarding decisions within equipment. All structures must pass through the actual central SP motor by the switch fabric or even coach. Coach as well as crossbar switching settings make use of the central SP.

Along with utilisation of the Distributed Sending Credit cards (DFCs) at risk segments, distributed switching can occur. With dispersed switching, sending occurs locally at risk segments which avoid the actual central switching motor around the boss engine, as well as packets are submitted straight between 2 ports or even across the change material.

In the event that traffic is ingress on the greeting card that is DFC equipped, the actual DFC works the hardware switching for that collection card. Consequently, you need to look into the equipment CEF records around the DFC by itself when trouble shooting. You should use the display material switching-mode order to check on whether the line card is actually DFC outfitted. If the output says "DCEF" (showing distributed CEF [dCEF]) under changing mode, it has a DFC. 9131252012wed

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