3C015
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3Com DynamicAccess® Software Version 1.5 Feature Overview |
DynamicAccess software adds intelligence to 3Com NICs for improved performance, management, and control of your network. DynamicAccess software 1.5 is a single piece of software, or an "advanced network driver," that integrates dRMON, Fast IP, Traffic Prioritization, and Efficient Multicast Control support. The DynamicAccess software release 1.5 components are:
| Feature | Benefit |
|---|---|
| Distributed RMON (dRMON) | Enables full RMON reporting on all network segments, even in switched networks, without sacrificing performance and without needing to place dedicated RMON probes throughout the network. |
| Traffic Prioritization (using IEEE 802.1p Class of Service [CoS] and IP Type of Service [ToS]) |
Provides a standards-based solution, preventing delays in transmissions of mission-critical or real-time traffic. Also extends this capability to the WAN. |
| Fast IP (NHRP-based shortcut routing) |
Alleviates router bottlenecks in today's any-to-any networks and intranets, where a growing percentage of traffic travels between rather than within subnets. |
| Efficient Multicast Control (using IEEE 802.1p GMRP) |
Prevents flooding of switched networks by multicast applications such as
video training, stock quotes, or online news. |
| Tivoli Management Agent | Provides central update and control capabilities transparent to the user, significantly reducing administration costs. 3Com has partnered with Tivoli Systems Inc. to deliver a simple, low-cost DynamicAccess software distribution application [summer 1998]. |
Basic local management is provided at the end system in the form of a Control Panel utility. Remote management is achieved through using the Control Panel utility to create a configuration settings file that can be used in login scripts to set the end node DynamicAccess software features.
For non-technical questions or comments about the DynamicAccess software
version 1.5 product, please send e-mail to:
DA_Feedback@3com.com.
Click here for installation instructions.
This software release includes 3Com's dRMON DynamicAccess software. You can use this new client software to replace the dRMON SmartAgent software you previously installed on the end node PC's at your site. This new software offers easy centralized installation and improved performance. However, the new client software does not operate with the Auto-Update utility shipped with the Transcend dRMON Edge Monitor System. A replacement utility will be available at the same time as the next release of the Edge Monitor. For details about dRMON, click http://www.3com.com/products/dsheets/400310.html .
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If you have already installed the DynamicAccess software release 1.5 on your end nodes and now plan to install the Transcend dRMON Edge Monitor System, you do not need to install the dRMON SmartAgent software from the product CD on to your end nodes. You only need to ensure that the password you set for the end nodes with KEYSET.EXE matches the password you use for your Edge Monitor. |
Ethernet architecture was designed to be a best-effort information delivery technology. However, new and increasing numbers of applications demand differentiated services for traffic over the network. To meet this challenge, the IEEE redefined the 802.1 standard to provide support for multiple service levels. Based on new defined fields in the Ethernet frame, the 802.1p standard provides eight levels of priority that network managers can use to ensure that mission-critical applications will receive priority over normal, noncritical applications during traffic congestion periods.
802.1p Prioritization802.1p prioritization is a new standard that provides Class of Service at the switch level to Ethernet networks. In order for the prioritization to be applied throughout the network, you must have switches and NICs in your network that support 802.1p. DynamicAccess software 1.5 provides 802.1p functionality for your 3Com NICs. If you have not yet deployed 802.1p enabled switches in your network, 3Com does not recommended that the 802.1p prioritization be enabled as connectivity problems can arise. You can, however, continue to use PACE and IP ToS prioritization.
The figure depicts an arrangement where NIC1 and NIC2, which have DynamicAccess software 1.5 with 802.1p prioritization enabled, can communicate with the SERVER, which does not support 802.1p. This communication is feasible because an 802.1p enabled switch can be configured to remove the 802.1p prioritization tag before sending it to the SERVER. This configuration is only one of many possible configurations where communication can be interrupted if not correctly configured. The general rule is that if you want an 802.1p enabled node to communicate with a non-802.1p enabled node, there must be at least one 802.1p enabled switch in the communications path.
Class of Service (CoS) allows you to prioritize traffic over the LAN. DynamicAccess software provides interaction between end stations and LAN switches for end-to-end service level implementations. NICs with DynamicAccess software 1.5 are able to identify selected applications and to tag frames according to network-defined configurations. Network managers are able to globally configure their network applications. These frames are received by 802.1p-enabled Layer 2 switches that, in turn, map incoming traffic to the corresponding switch queue, hence, providing consistent traffic delivery for critical traffic.
DynamicAccess software version 1.5 provides support for the IP and IPX protocols. Network managers can select applications from the built-in list or enter new applications. The CoS module looks at the application IP port or IPX socket number to identify application streams. If the required application is not in the list, network managers can enter the port or socket number and add prioritization for the application to their systems. The use of LAN protocol analyzers may be necessary to identify the port/socket number used by specific applications.
Traditionally, all IP packets have had the same "class of service," which is a best-effort datagram service. In times of congestion, all packets are equally likely to be discarded. Despite the existence of a Type of Service (ToS) octet in the IP header, no real support for different types of service (other than best-effort) had been deployed until recently.
A desire to offer an Internet with so-called "better than best-effort" service has motivated many parties to reexamine how the ToS octet may be used to help certain traffic types achieve better end-to-end performance. The ToS octet contains three "precedence" bits and four ToS bits. Emerging "differential services" proposals use the IP ToS octet as well, to allow end-stations and routers to set the priorities of their traffic on an end-to-end basis.
The IP precedence bits feature allows a PC to indicate a desired end-to-end Layer 3 traffic priority across any intervening LAN and WAN links. Software at the NIC level sets the IP precedence bits, which routers use as an indication for preferring certain traffic priority levels over others.
In DynamicAccess software, the IP precedence bits (from the Internet Protocol's ToS octet) are mapped to IEEE 802.1p priority bits. Therefore, routers may prioritize traffic using Layer 3 information, and switches may also prioritize packets through Layer 2 links between end-stations, between end-stations and routers, or between routers.
Because these precedence bits are inside the IP header, they can only be used to prioritize native IP traffic (e.g., TCP/IP or UDP/IP) or traffic that is transported across IP tunnels. The IP precedence bits cannot be used to prioritize non-IP traffic such as IPX, AppleTalk, or Vines.
IP Precedence Bits for IP TrafficDynamicAccess software support for IP Precedence permits software at the NIC level to pretag IP packets with an explicit Layer 3 priority, which allows routers to make more-informed forwarding decisions. When a router receives a packet with a pretagged IP Precedence value, it does not need to waste cycles attempting to classify each packet. The routers along the end-to-end path simply use the IP precedence bits as an indication to guide them in decisions about the order in which to forward packets.
When planning to deploy non-default IP Precedence, keep in mind that your routers and switches in the path between any two of your ToS-enhanced end stations must be configured to prioritize traffic based on either 802.1p tags, the precedence bits in the IP ToS octet, or both 802.1p and IP ToS. End stations may set nondefault ToS bits, but intermediate devices that do not understand these rules will simply forward packets on a best-effort basis.
In normal switched Ethernet environments, multicasts are treated exactly like broadcasts and are forwarded to every active port. Efficient Multicast allows end stations to register for multicast traffic and communicate their multicast interest to the nearest 802.1p GMRP-enabled switch. The switch then knows that the registered multicast traffic should be forwarded to that port. That multicast traffic is NOT forwarded to ports that did not register for it. Efficient Multicast thus reduces the forwarding load on switches and prevents end stations from receiving unwanted multicast traffic.
Efficient Multicast allows NICs to work with 802.1p-compliant switches to register for multicast group membership. This membership means that multicast traffic can be filtered to only those segments that need to be part of the multicast group. For Efficient Multicast to operate correctly, your network must incorporate 802.1p GMRP-compliant switches. If a particular switch does not understand GMRP, it will simply treat the packet like any other packet.
VLAN Registration (Group Virtual LAN Registration Protocol [GVRP]) is very similar to Efficient Multicast and in the DynamicAccess software version 1.5 it is used with the Fast IP feature. VLAN registration enables the end node to tell the 802.1Q-aware switch which VLAN traffic to send to the end node.
For VLAN Registration to operate correctly, your network must incorporate 802.1Q-compliant switches.
PACE™ TechnologyThis software release includes 3Com's PACE™ technology. This innovative technology provides network managers with the tools they need to prioritize traffic according to their business needs. PACE technology solves both the technical and business challenges necessary to enhance real-time, interactive, and mission-critical applications by improving network bandwidth utilization, reducing latency, controlling jitter, and supporting several traffic priority levels. PACE technology allows network managers to maximize their existing Ethernet infrastructure and make the most of Fast Ethernet networks.
PACE technology requires end stations and servers to be connected to the 3Com SuperStack® II Desktop Switch, Switch 1000, and Switch 3000, the LinkBuilder® MSH™ Switch Module, or the CoreBuilder™ 5000 (formerly ONcore®) FastModules. PACE was designed by 3Com in 1994 and is based on existing Ethernet standards. Being independent technologies, 3Com's DynamicAccess software maintains support for PACE users while supporting the emerging 802.1p CoS standard. You can configure your networks to support either or both standards.
Refer to the documentation that was shipped with your 3C90x NIC regarding configuration instructions for enabling PACE technology.
Copyright ©1998, 3Com Corporation.
Unless otherwise indicated, 3Com registered trademarks are registered in the United States
and may or may not be registered in other countries. 3Com, DynamicAccess,
EtherDisk, EtherLink, LinkBuilder, OnCore, SmartAgent, and SuperStack are registered
trademarks of 3Com Corporation. CoreBuilder and PACE are trademarks of 3Com Corporation.
