My TN Connection

As I was looking back on some of the Switch Sense posts and training some new employees here at Transition Networks I was reminded of how many acronyms and interpretations there are for standards and features that are related to Ethernet switches.

Most of us take these terms for granted, but when talking to people you often uncover people using two different meanings or interpretations for the same feature. With that in mind I thought it would be great to put together a simple glossary with Ethernet switch terminology that tells what the feature is, if it is known as something else, if it is an IEEE or RFC standard along with a simple description. continue »

Internet Group Management Protocol (IGMP) is a way to restrain broadcast or multicast traffic in a switched network. With unicast traffic, an Ethernet switch learns MAC addresses by looking into the source address field of every frame. However, with multicast packets the Ethernet switch must deal with a multicast MAC header which may or may not appear in its table. Consequently, multicast packets are copied and transmitted or “flooded” to every port. During multicast floods or transmissions devices are unable to use the network, thus wasting bandwidth at best and preventing control data from being sent at worst. The effect of multicast floods is particularly bad with full-duplex links, because the bandwidth consumed is proportional to the number of attached nodes which each invite a multicast packet.

IGMP prevents a flood of packets from congesting a network segment where a node is not interested in receiving the packets. IGMP is an integral part of IP and is used by routers to report their multicast status to nearby routers. continue »

What is Super Ring? Let me first explain Spanning Tree Protocol (STP) and Rapid Spanning Tree Protocol (RSTP). With dealing with Ethernet switches and a solution that involves using multiple switches connected together one must be aware of possible bridge loops.

As an example, if you were to not have a switch that supports STP or RSTP and had multiple active paths between network switches a bridge loop would occur. Bridge loops will create several problems for you like the MAC address table used by the switches could fail since the same MAC addresses are seen on multiple ports. Also, a broadcast storm will occur which will send out unwanted traffic across your network, this will consume all available CPU resources and bandwidth. continue »

Network switches can provide open and easy access to network resources by simply attaching a client PC. While this automatic configuration and access is a desirable feature, it also can allow for unauthorized personnel to easily intrude and possibly gain access to sensitive information.

802.1x is an excellent way for securing data networks and restricting unauthorized clients and machines from connecting to LAN switch ports. The following will briefly cover why 802.1x was developed, what it is and how it is deployed. This high level information is meant to give you a basic understanding of 802.1x and how it could be used in our network. continue »

Network administrators may wish to manage multiple Ethernet switches via a single IP address.  The reasoning for this is if they have a rack of switches and don’t want to remember multiple IP addresses or if they need to reduce the number of IP addresses for devices that are being deployed in their network.

While there is no standard for managing multiple Ethernet switches via a single IP address most manufactures do offer managed switches with this capability.   Some of the names you may see and hear for this concept are Switch Clustering, IP Stacking and Virtual Stack Management to name a few.  The concept is the same across the various manufactures, but it may be implemented in a different manner so you can not manage multiple vendors’ switches via a single IP address since this is not an IEEE standard and each manufacture implements this in a proprietary manner. continue »