Packet rings

Overview

Packet Ring configurations provide business-to-business networking of routers and data switches using Ethernet transport over a reliable, low-cost multiservice network. Alcatel-Lucent 1665 DMX provides the unique capability for a packet ring to span multiple ring topologies. As shown in the figure below packet rings hosted by Alcatel-Lucent 1665 DMX can span multiple OC-192, OC-48, OC-12, OC-3 ring configurations (UPSRs or BLSRs). Additionally, packet rings hosted by Alcatel-Lucent 1665 DMX can reach into areas serviced by dual and single-homed ring extensions (see the figure below).

Ethernet over SONET

A Packet Ring is a set of packet switches connected in a ring topology that use the inherent redundancy of the ring configuration to provide durability and fast restoration in the event of failures.

Packet rings can be used with or without SONET layer protection. At the packet layer, the rapid spanning tree protocol (as defined in IEEE 802.1) is used to provide protection.

Figure 3-27: Packet rings

Alcatel-Lucent 1665 DMX uses standard Generic Framing Procedure (GFP) encapsulation (ITU G.7041) for Ethernet over SONET mapping. Packet rings provide efficient aggregation and transport for Ethernet traffic. Alcatel-Lucent 1665 DMX's virtual concatenation capability (ITU G.707) provides flexible bandwidth granularity in the wide area network (WAN), which can grow with your service demand.

Packet rings over a BLSR

Alcatel-Lucent 1665 DMX allows the manual provisioning of nonpreemptive unprotected traffic (NUT) for multi-point Ethernet cross-connections that originate on low-speed (tributary) interfaces and share bandwidth on the high-speed (Network side) BLSR ring.

When using multi-point cross-connections through a BLSR, packets do not receive standard BLSR protection due to the necessary functioning of NUT. Yet, protection on all data packets is provided for with rapid spanning tree protocol (IEEE 803.1w).

Packet ring capacity

Alcatel-Lucent 1665 DMX supports the following number of packet rings per Ethernet interface circuit pack:

• 1 packet ring on each 10/100 Mbps Fast Ethernet circuit pack (LNW66)

• 16 packet rings on each 10/100/1000 Mbps GbE circuit pack (LNW170)

Specific applications supported

Alcatel-Lucent 1665 DMX supports the following enterprise LAN (local area network) interconnect and transport applications:

• Ethernet Private Line

• Ethernet Rate Control Services

• Virtual LAN Services

• Transparent LAN Services

• Best Effort Service

• Ethernet/TDM Access to Frame Relay or ATM Network

• Ethernet/TDM Access to IP Network

• DSLAM Access

Each of these packet ring applications are detailed in the "Service Applications" section of this chapter.