ServSwitch Agility and Agility Dual

Appendix C. Glossary

C.1 Internet Group Management Protocol

Where an ServSwitch Agility transmitter is required to stream video to two or more receivers, multicasting is the method used.

Multicasting involves the delivery of identical data to multiple receivers simultaneously without the need to maintain individual links. When multicast data packets enter a subnet, the natural reaction of the switches that bind all the hosts together within the subnet, is to spread the multicast data to all of their ports. This is referred to as Multicast flooding and means that the hosts (or at least their network interfaces) are required to process plenty of data that they didn’t request. IGMP offers a partial solu- tion.

The Internet Group Management Protocol (IGMP) is designed to prevent multicast flooding by allowing Layer 3 switches to check whether host computers within their care are interested in receiving particular multicast transmissions. They can then direct multi- cast data only to those points that require it and can shut off a multicast stream if the subnet has no recipients.

There are currently three IGMP versions: 1, 2 and 3, with each version building upon the capabilities of the previous one:

•IGMPv1 allows host computers to opt into a multicast transmission using a Join Group message, it is then incumbent on the router to discover when they no longer wish to receive; this is achieved by polling them (see IGMP Querier below) until they no longer respond.

•IGMPv2 includes the means for hosts to opt out as well as in, using a Leave Group message.

•IGMPv3 encompasses the abilities of versions 1 and 2 but also adds the ability for hosts to specify particular sources of multi- cast data.

ServSwitch Agility units make use of IGMPv2 when performing multicasts to ensure that no unnecessary congestion is caused.

C.1.2 IGMP Snooping

The IGMP messages are effective but only operate at layer 2 - intended for routers to determine whether multicast data should enter a subnet. A relatively recent development has taken place within the switches that glue together all of the hosts within each subnet: IGMP Snooping. IGMP snooping means these layer 2 devices now have the ability to take a peek at the IGMP messages. As a result, the switches can then determine exactly which of their own hosts have requested to receive a multicast – and only pass on multicast data to those hosts.

C.1.3 IGMP Querier

When IGMP is used, each subnet requires one Layer 3 switch to act as a Querier. In this lead role, the switch periodically sends out IGMP Query messages and in response all hosts report which multicast streams they wish to receive. The Querier device and all snooping Layer 2 switches, then update their lists accordingly (the lists are also updated when Join Group and Leave Group (IGMPv2) messages are received).

C.1.4 IGMP Fast-Leave (aka Immediate Leave)

When a device/host no longer wishes to receive a multicast transmission, it can issue an IGMP Leave Group message as men- tioned above. This causes the switch to issue an IGMP Group-Specific Query message on the port (that the Leave Group was received on) to check no other receivers exist on that connection that wish to remain a part of the multicast. This process has a cost in terms of switch processor activity and time.

Where ServSwitch Agility units are connected directly to the switch (with no other devices on the same port) then enabling IGMP Fast-Leave mode means that switches can immediately remove receivers without going through a full checking procedure. Where multiple units are regularly joining and leaving multicasts, this can speed up performance considerably.

Page 40

724-746-5500 blackbox.com

Page 39 Page 41
Page 40
Image 40
Black Box ACR1002A-T, ACR1000A-T manual Appendix C. Glossary Internet Group Management Protocol, Igmp Snooping, Igmp Querier
Page 39 Page 41

ACR1000A, ACR1000A-R, ACR1002A, ACR1002A-T, ACR1002A-R specifications

The Black Box ACR1000A-T, ServSwitch AgilityTM, Agility DualTM, ACR1002A-R, ACR1002A-T, and ACR1002A are advanced solutions designed to optimize switching and management capabilities in complex IT environments. These devices cater to various needs, primarily focusing on KVM (Keyboard, Video, Mouse) switching and user-friendly operations, making them invaluable in data centers, server rooms, and large corporate infrastructures.

The Black Box ACR1000A-T is known for its robust functionality and versatility. It supports video resolutions up to 4K, ensuring high-quality output for a range of applications. This model utilizes dual-channel audio support, enhancing multimedia experiences, while its convenient USB connectivity allows seamless integration with modern peripherals. The ACR1000A-T is designed with a user-friendly interface, simplifying multi-computer management by enabling users to effortlessly switch between systems with a push of a button.

The ServSwitch AgilityTM series elevates performance with efficient switching and extended connectivity options. Designed for high-resolution support, it ensures minimal latency in video transmission. With features such as USB and audio handling, the AgilityTM series provides an inclusive multi-functional experience, allowing users to control multiple machines from a single workstation effortlessly. The enhanced firmware updates ensure that the AgilityTM series remains on the cutting edge of technology, adapting to evolving user demands.

For environments requiring dual-access capabilities, the Agility DualTM provides a unique solution. It enables two users to share control over two different systems simultaneously, offering great flexibility and collaboration in diverse workflows. This innovative approach enhances productivity by allowing one user to work on one system while the other manages a different task, all without needing to switch setups.

The ACR1002A-R, ACR1002A-T, and ACR1002A devices focus on scalability and performance. These models come equipped with comprehensive management features, including remote access capabilities and support for various video resolutions. Ideal for IT administrators, these devices streamline operations, simplifying maintenance and offering excellent reliability.

In summary, the Black Box ACR1000A-T, ServSwitch AgilityTM, Agility DualTM, ACR1002A-R, ACR1002A-T, and ACR1002A represent cutting-edge advancements in KVM technology. With their combination of high-resolution support, user-friendly interfaces, and scalability, they are essential tools in managing multiple computing environments efficiently. These devices not only enhance productivity but also align with the evolving needs of businesses in today's fast-paced digital landscape.
Top Page Image Contents