Georg Pauwen wrote: > 4A collapsed backbone has high-bandwidth uplinks from all segments and > subnetworks to a single device, such as a Gigabit switch, which serves as a > single point for monitoring and controlling the network4. > > The following link contains a figure detailing the collapsed backbone design > using a Cat4908G-L3: > > http://www.cisco.com/univercd/cc/td/doc/product/lan/c2900xl/29_35wc/sc/swgover.htm
Another way to look at collapsed backbones is to consider why it's called "collapsed". Cisco uses a hierarchical campus model that scales down to small one-room networks and up to enterprise-wide networks that include multiple buildings. The full model has three "tiers" or "layers" (access, distribution, core) and multiple types of building blocks (switch block, core block, server block, mainframe block, WAN block). I don't have statistics but I've seen a lot more collapsed networks than networks that fit the full 3-tiered multi-block multi-building campus model. The collapsed model is very popular and can scale up to hundreds of endsystems and dozens of workgroups (VLANs). All you need is a high-end switch, gigabit cabling (preferably fiber but cat 5e/6 works just fine if you keep the cable lengths in the 90m range and if you don't have EMI to worry about), and a high-end router to serve as a firewall and gateway to the outside. Some of the endsystems can be home-run directly back to the main switch, or they can be aggregated at active or passive consolidation points. The router can be a standalone or can be included in the same chassis as the main switch such as a "route service module" or "layer 3 services module". Cheers, -- TT Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=41422&t=41418 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
