Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1998-03-16
2001-02-13
Kizou, Hassan (Department: 2736)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S397000, C370S399000, C370S409000
Reexamination Certificate
active
06188691
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to computer networking and more particularly relates to a method of creating session layer VLANs.
BACKGROUND OF THE INVENTION
Currently, the number of networks around the world is growing at a faster and faster pace. In addition to new networks being installed existing networks are being upgraded and expanded as companies increase in size and more and more users are added to internal networks. Enterprise networks are presently enjoying a huge increase is popularity with thousands of new nodes and users being added each week. The increased number of users is forcing these enterprise network administrators to add more equipment to meet surging demand and is also forcing the bandwidth capabilities of the enterprise network to increase both in terms of new communication links being added and slow speed links being upgraded to higher bandwidth links.
The use of multicast messages for point to multipoint communications is expected to help alleviate congestion and reduce bandwidth consumption on most enterprise networks in the future. Presently, its use is limited as much of the equipment, i.e., routers etc., that is in use on enterprise networks does not support the new multicast protocols. Eventually, the use of multicast protocols on enterprise networks, will significantly reduce the traffic required to be sent for point to multipoint type communications.
Further, scaleable switching technology has enabled the construction of large switched networks. Broadcast traffic forwarding, however, does not scale well in large networks because all the network hosts are exposed to broadcasts from all other hosts. In other words, in level 2 networks, i.e., networks operating at the link layer in the ISO communication stack, large portions of bandwidth are wasted as each node on the level 2 network receives all multicast traffic. Under normal conditions, multicast traffic is flooded to all stations on the network, thus degrading performance. A suitably configured router (level 3 device) functions to filter the multicast traffic and only forward it to network segments that should receive it. Absent a router or other level 3 filtering, however, each node or workstation on the level 2 network will receive all multicast traffic. Thus, the filtering is performed at each station that receives multicast messages.
Prior art attempts at reducing bandwidth waste in connection with multicast traffic include assigning filters within level 2 switches that function to scan and filters the content of every frame that is received. This requires more complicated hardware and/or software content within the switch which drives up its cost significantly.
In addition, in response to the broadcast traffic flooding problem described above, VLANs can be used to partition the broadcasts into domains that permit the switched network to keep growing. Since it is common nowadays to connect network ports to the switched infrastructure rather than routers or servers, the logical partition of the network no longer directly effects the configuration of higher layer devices. Thus, network administrators can more easily assign and reassign network regions to logical groups without expensive reconfiguration of the host, router or server.
Typically, Media Access Control (MAC) layer multicast messages are forwarded according to the VLAN broadcast data path. However, while broadcast forwarding is usually related to address resolution/SAP) location type administrative traffic, the nature of multicast traffic is usually very different. Multicast traffic, especially IP multicast traffic is typically associated with particular types of application such as video broadcasting and video conferencing. These applications are typically characterized by: (1) setup of a group communication session (2) high traffic volume and (3) the crossing of VLAN boundaries that were previously setup for subnetting purposes.
In addition, conventional VLAN capable network devices are not capable of containing multicast traffic flooding since all regular members of the VLAN will hear multicast traffic. Further, the implementation of the VLAN itself is vendor specific. For example, some implementations are port based while others are based on other criteria.
SUMMARY OF THE INVENTION
The present invention serves to alleviate the problems associated with the prior art by disclosing a method whereby local area network (LAN) multicast traffic flows are defined and set up by the network management system (NMS). This serves to maximize network efficiency and avoids the performance degradation of the network and workstations connected thereto. Utilizing the standard 802.1D bridging infrastructure that is built into conventional level 2 network switching devices, the method of the present invention functions to permit an administrator to define a multicast flow, otherwise known as a virtual LAN (VLAN) or a ‘Session VLAN,’ as a multicast application that can be mapped to a multicast MAC address. The multicast MAC address is then utilized in the transmission of the multicast messages.
For example, the administrator can assign an IP multicast address to a specific video channel or a video conference. Once assigned, standard Internet Authority for Number Assignment (IANA) mapping is used to derive the multicast MAC address from the IP multicast address. Then, the NMS declares a session VLAN across all the level 2 devices in the network utilizing the standard simple network management protocol (SNMP). Level 2 devices may include any device that functions to examine the level 2 frame content of messages, such as bridges, virtual bridges and switches. The user or administrator has the capability of adding and deleting segments from the VLAN thus created. The user's additions and deletions are translated into SNMP requests which are then transmitted over the network to each level 2 device. Each device then translates the SNMP requests to an operation on its standard 802.1D static addresses.
Thus, the method of the present invention functions to create a concept of the multicast flow, i.e. session VLANs, at the NMS application utilizing a method and framework that expresses the special semantics of a MAC multicast address. It is important to note that rather than map MAC addresses to bridge segments locally, i.e., from the perspective of a single device, using straightforward bridge management MIB manipulation, the user is presented with a view that maps bridge segments to a high level network concept. The high level network concept being the specific multicast service flow previously termed the session VLAN.
The method and approach described above in combination with standard bridging capabilities, i.e. 802.1D bridging, enables complex multicast environments to be created and administered within existing standard bridged networks without the need to upgrade network device hardware or communication protocol stacks.
There is provided in accordance with the present invention a method of establishing a session layer Virtual Local Area Network (VLAN), comprising the steps of defining a multicast flow and assigning members of the session layer VLAN to the multicast flow, mapping a multicast IP address assigned to the session layer VLAN to a multicast Media Access Control (MAC) address, declaring a session layer VLAN across all level 2 devices in the network and enabling multicast MAC traffic on those ports of the level 2 devices corresponding to the members o the session layer VLAN.
The step of enabling multicast MAC traffic utilizes standard 802.1D bridging infrastructure and the step of declaring a session layer VLAN comprises a Network Management System (NMS) sending a primitive to create a session layer VLAN to all level 2 devices in the network. The primitive may comprise a VLAN Create primitive.
In addition the NMS sends the primitive utilizing Simple Network Management Protocol (SNMP) to all level 2 devices in the network and the step of enabling multicast MAC traffic comprises the step of a Network Manage
Bar-Eli Eldad
Barkai Sharon
Shamir Yoram
3Com Corporation
Kizou Hassan
Slavitt Mitchell
Weitz David J.
Wilson Sonsini Goodrich & Rosati
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