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última version al 18:24 25 ene 2012

CEF Switching Structures around the 'cisco' Driver 6500 Around the SUP720, Cisco Driver 6500 utilizes CEF, which cannot be disabled, to provide hardware effectiveness. Rather than performing changing in software as prior 'cisco' routers did, the Cisco Catalyst 6500 performs changing within hardware using CEF. You need to understand this particular distinction when troubleshooting issues concerning a SUP720.

Knowing Software-Based CEF and Hardware-Based CEF Hardware-based CEF box changing leverages the present information structures constructed by CEF within software program after which stretches the capability in order to equipment through programming specific hardware memories with information the sending The company can use in order to quickly transfer packages for enhanced overall performance. Within software-based CEF, the actual router builds the actual Forwarding Info Base (FIB) and adjacency furniture in line with the redirecting as well as Deal with Quality Process (ARP) furniture. The Catalyst 6500 switch stores this information in hardware high-speed table storage as well as utilizes efficient research algorithms for desk searches. In the Catalyst 6500, these high-speed memory furniture tend to be Ternary Content material Addressable Storage (TCAM) furniture. TCAM utilizes a mixture of worth matching having the ability to mask for a particular result. In this case, it makes sense the pointer for an entry in the equipment adjacency table which has the next-hop Macintosh reword info.

The actual SUP720 lists FIB records in the TCAM desk in the most particular to the least specific entry. Consequently, the TCAM listings just about all entries having a subnet mask of Thirty-two (host entry) for the prefix very first. Once the FIB as well as adjacency furniture within the TCAM are complete, the actual SUP720 punts traffic for that unfound destination/entry to the software-switching motor (route processor, or RP) to become handled within software program. The SUP720 comes with an integrated RP as well as change processor (SP) on the Multilayer Switch Feature Greeting card 3 (MSFC3). The actual SP handles typical Layer Two capabilities for example Spanning Tree and VLAN Trunking. The actual RP handles typical Coating Three capabilities such as Improved Interior Gateway Routing Protocol (EIGRP) as well as redirecting.

The actual SUP720 also has a Policy Function Greeting card 3 (PFC3) to aid hardware-based forwarding and features for example routing, multicast packet duplication, as well as entry control listings (ACLs). Several PFC3s, like the PFC3B and the PFC3BXL, are available. On a SUP720 with a PFC3BXL, the actual FIB TCAM size and the adjacency desk dimensions are 1 million entries. The type of functions enabled can affect the number of TCAM records the SUP720 uses to keep info. Every Internet protocol version Four (IPv4) location prefix recognized takes one entry within the TCAM. Consequently, the actual PFC3BXL version facilitates a large number of IPv4 routes and adjacencies that can be contained in a large enterprise or even company system. Nevertheless, along with IPv6 and ingress multicast routes, every location requires 2 records within the TCAM. Make reference to 'cisco'.com for that latest information associated with whether an element influences the entire quantity of entries stored in TCAM.

The actual SUP720 forces software CEF info down to the actual equipment The company, which could manage the actual box sending faster. The actual RP on the SUP720 sends the information towards the SP to program the TCAM and the equipment The company.

Equipment FIB research happens based on the longest coordinating destination prefix. The complement in the equipment FIB based on the location prefix returns adjacency information that contains the actual packet rewrite info for that appropriate outgoing user interface. Then, sending from the box happens to the next hop within equipment. Observe that prior to the Cisco Catalyst 6500 passes the box outgoing, it also validates protection and excellence of service (QoS) guidelines to confirm the packet is legal and should not be fallen instead.

Central as well as Distributed Switching The actual Cisco Catalyst 6500 facilitates centralized changing or distributed switching. Central switching occurs when the change processor chip on the SUP720 makes sending choices within hardware. All frames should pass through the centralized SP engine by the switch fabric or even bus. Coach and crossbar changing settings use the centralized SP.

Along with use of the Distributed Forwarding Cards (DFCs) at risk modules, distributed switching can happen. Along with dispersed changing, sending occurs in your area at risk modules that avoid the centralized changing motor on the boss engine, and packets tend to be submitted straight in between two ports or even across the change fabric.

If traffic is ingress on a greeting card that's DFC outfitted, the actual DFC works the actual equipment switching for that line card. Therefore, you need to look into the hardware CEF entries on the DFC by itself whenever troubleshooting. You can use the actual display material switching-mode order to check regardless of whether a line card is DFC equipped. When the output says "DCEF" (indicating dispersed CEF [dCEF]) under changing mode, it has a DFC. 9131252012wed

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