Resource Library

The STP (Spanning Tree Protocol) standard (IEEE 802.1d) was designed when the recovery after an outage could wait a minute or so and be acceptable performance. With Layer 3 switching in LANs, switching began to compete with routers running protocols because they are able to offer faster alternate paths. Rapid Spanning Tree Protocol (RSTP or IEEE 802.1w) brought the ability to take the twenty seconds of waiting for the Max Age counter plus fifteen seconds of Listening plus fifteen seconds of Learning or fifty seconds down to less than one second for point-to-point connected and edge switches and six seconds for root switches.

In a recent post, I gave an overall description of a service portfolio and the key components of a portfolio. Here, I will describe how a cloud services provider might implement an ITIL service portfolio. A cloud services provider will regularly have a set of services under development, a set of service in live operation, and a set of services that are retired.

ITIL describes a service portfolio as a collection of the overall set of services managed by a service provider. A service portfolio describes a service provider’s boundaries and promises across all of the customers and market spaces it serves. I like to think of a service portfolio as describing the past, present, and future collection of services offered by a service provider. The figure below shows a high-level view of a service portfolio.

This short example illustrates basic VLAN operation. Examining VLANs in a large-scale installation can show the full benefits of VLANs. Consider that this is a small portion of a large corporate headquarters with 5,000 devices connected in a 20 building campus.

In 1998, the Internet Engineering Task Force (IETF) released RFC 2460, outlining the technical specifications of IPv6, which addressed the shortcomings of the aging IPv4 protocol. As with any evolution of technology, new elements exist in the protocol that may seem strange and unfamiliar. This certainly includes address representation, space, and so forth, but also includes a number of different types of addresses as well. A subset of these new addressing types has corresponding types in IPv4, but many will seem significantly different. The purpose of this white paper is to examine addressing classifications in detail and outline their functions within the context of the protocol.

Depending on the switch vendor, the exact steps will vary on how to set up and configure VLANs on a switch. For the network design shown, the general process for setting up VLANs on the switch is:

We already covered the first three of the twelve advantages of Agile software development. These three advantages focus on team development and refining the process. Advantage #4: Motivated Development Team The positive relationship with a reasonable and satisfied customer is only one of the reasons why many developers prefer to work on Agile projects. The other main contributor is that they tend to value working in self directed teams (which the Agile methods require for success).

Now that the network is installed, each switch has a bridge ID number, and the root switch has been elected, the next step is for each switch to perform a calculation to determine the best link to the root switch. Each switch will do this by comparing the path cost for each link based on the speed. For paths that go through one or more other switches, the link costs are added. The switch compares this aggregate value to the other link costs to determine the best path to the root switch.

There is a reason why the Agile methods are becoming mainstream. They can work! Although every Agile practice is not necessarily appropriate for every organization, each practice has delivered real value to many organizations, and some Agile practices can be used by anyone! This four part series explores twelve ways in which the Agile methods are valuable. I’ll bet that you will find more than a few that could be valuable for you!

That depends on their configurations. For example: While it makes very good sense to include redundant physical links in a network, connecting switches in loops, without taking the appropriate measures, will cause havoc on a network. Without the correct measures, a switch floods broadcast frames out all of its ports, causing serious problems for the network devices. The main problem is a broadcast storm where broadcast frames are flooded through every switch until all available bandwidth is used and all network devices have more inbound frames than they can process.