Bani, Lookin at the Book i found this There is a difference of what you say ??
Regards Victor. 106 Chapter 4: VLANs and Trunking End-to-End VLANs End-to-end VLANs, also called campus-wide VLANs, span the entire switch fabric of a network. They are positioned to support maximum flexibility and mobility of end devices. Users are assigned to VLANs regardless of physical location. As a user moves around the campus, that user’s VLAN membership stays the same. This means that each VLAN must be made available at the access layer in every switch block. End-to-end VLANs should group users according to common requirements. All users in a VLAN should have roughly the same traffic flow patterns, following the 80/20 rule. Recall that this rule estimates that 80 percent of user traffic stays within the local workgroup, while 20 percent is destined for a remote resource in the campus network. Although only 20 percent of the traffic in a VLAN is expected to cross the network core, end-to-end VLANs make it possible for all traffic within a single VLAN to cross the core. Because all VLANs must be available at each access layer switch, VLAN trunking must be used to carry all VLANs between the access and distribution layer switches. (Trunking is discussed in later sections of this chapter.) Local VLANs Because most enterprise networks have moved toward the 20/80 rule (where server and intranet/Internet resources are centralized), end-to-end VLANs have become cumbersome and difficult to maintain. The 20/80 rule is reversed—only 20 percent of traffic is local, while 80 percent is destined to a remote resource across the core layer. End users require access to central resources outside their VLAN. Users must cross into the network core more frequently. In this type of network, VLANs are designed to contain user communities based on geographic boundaries, with little regard to the amount of traffic leaving the VLAN. Local or geographic VLANs range in size from a single switch in a wiring closet to an entire building. Arranging VLANs in this fashion enables the Layer 3 function in the campus network to intelligently handle the inter-VLAN traffic loads. This scenario provides maximum availability by using multiple paths to destinations, maximum scalability by keeping the VLAN within a switch block, and maximum manageability. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=74782&t=74593 -------------------------------------------------- **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html
