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Table Of Contents
5.1.1 Multiplexing Structure and Mapping Modes
5.4.3 Standard, Non-Clearable Alarms
5.4.4 Managed Objects and Related Events
5.5 Internet Index Reference Numbers
Features
This chapter provides an overview of the ONS 15305 features.
5.1 SDH Features
5.1.1 Multiplexing Structure and Mapping Modes
The ONS 15305 supports the multiplexing structure shown in the figure below. This is a subset of the possible multiplexing structures defined in ITU-T G.707 clause 6, according to ETS300147. The multiplexing complies with ITU-T G.707 clause 7.
Figure 5-1 Multiplexing Mapping Structure
The ONS 15305 support asynchronous mapping of E3 (34 368 kbps) signals and T3 (44 736 kbps) signals into a VC-3 according to ITU-T G.707 clause 10.1.2, and asynchronous mapping of E1 (2 048kbps) signals into a VC-12 according to ITU-T G.707 clause 10.1.4.1.
The ONS 15305 also provides a mapping scheme for transporting Ethernet traffic in a number of VC-12s. The mapping is performed in a round-robin fashion with an inverse multiplexer function. The mapping between Ethernet and SDH is performed in WAN ports that are located on the 8xSTM-1 module.
The proprietary mapping scheme used is described in Figure 5-2. Only the mapping is proprietary; all POH in the VC-12 complies with ITU-T G.707.
Figure 5-2 Ethernet Mapping Scheme
The total bandwidth for one WAN channel cannot be greater than 100 Mbps or 50xVC-12 containers. The mapping between the tributary interfaces and the WAN port is fully flexible, and controlled in the same way as a VC-12 cross connect.
5.1.2 SOH and POH Termination
5.1.2.1 RSOH and MSOH
The ONS 15305 terminates and generates a subset of the SOH-overhead specified in ITU-T G.707 clause 9.
The SOH for an STM-1 is reproduced in Figure 5-3.
Figure 5-3 SDH Overhead Bytes
The ONS 15305 generates and terminates the following bytes:
5.1.3 Cross-Connect
The ONS 15305 implements a full non-blocking 64x64 STM1 cross-connect with VC12, VC-3, and VC-4 granularity.
The cross-connect supports bidirectional cross-connections on all levels.
5.1.4 Protection
5.1.4.1 1+1 Linear MSP
The ONS 15305 offers 1+1 Linear Multiplex Section Protection (MSP). The protocol used for K1 and K2 (b1-b5) is defined in ITU-T G.841, clause 7.1.4.5.1. The protocol used is 1+1 bidirectional switching compatible with 1:N bidirectional switching.
The MSP protection is not linked to a pair of ports on the same module; ports on modules 1 and 2 can protect each other and ports on modules 3 and 4 can protect each other if they are the same type.
Figure 5-4 Protection Scheme for the ONS 15305
5.1.4.2 SNC/I
The ONS 15305 also support Subnetwork Connection Protection with Inherent Monitoring (SNC/I) on both LO and HO VCs. The Application architecture supported is 1+1 unidirectional switching according to ITU-T G.841, clause 8.3.2.
Note
This protection scheme is called SNCP by ETSI.
5.1.5 Performance Monitoring
The ONS 15305 offers full G.826/G.829 performance monitoring on all levels in the SDH hierarchy, including B1 monitoring in RSOH, B2 near and far end in MSOH, B3 near and far end at VC-4/VC-3 level and BIP-2 near and far end at VC-12 level.
The ONS 15305 calculates excessive error and degrade signal defects assuming Poisson distribution of errors, according to ITU-T G.826.
The excessive error defect (dEXC) is be detected if the equivalent BER exceeds a pre-set threshold of 10E-5, and is cleared if the equivalent BER is better than 10E-6, according to ITU-T G.806.
The degraded signal defect (dDEG) is detected if the equivalent BER exceeds a pre-set threshold of 10E-X, where x=6,7,8 or 9. The dDEG is cleared if the equivalent BER is better than 10E-(X+1), according to ITU-T G.806.The threshold is individual configurable for the different levels in the SDH hierarchy, from 10E-6 to 10E-9.
5.1.6 Synchronization
The ONS 15305 offers synchronization from a range of different interfaces:
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Through the SETS (Synchronous Equipment Timing Source), the synchronization signals are distributed to the equipment ports.
The ONS 15305 offers a list of 5 possible synchronization sources for the T0; selection of the sync source is based upon the quality level.
The ONS 15305 supports SSM messaging on the STM-N interfaces, which is not supported on the E1 interface.
5.2 IP Features
ONS 15305 supports a transparent multiport remote Ethernet bridge as specified in IEEE 802.3. The number of interfaces depends on the inserted modules. The plug-in modules support 10Base-T over copper, 100Base-TX (fast Ethernet) over copper, gigabit Ethernet (GE) over fiber, and a proprietary STM-1 interface for connection to the ONS 15302 product.
The bridge supports the following features:
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The filtering rate of the bridge can operate at full wire speed (up to 1 Gbps). The forwarding rate is only limited by the forwarding interface speed. BootP is used to get one IP address for the ONS 15305 during the installation process.
5.3 DCN Features
This section presents the ONS 15305 protocol stack, interfaces, and communication functions used for management communications.
5.3.1 Protocol Stack
Figure 5-5 DCN Protocols
The following standards apply:
5.3.2 Management Interfaces
The purpose of the Management DCN is to carry management traffic between a management system and the managed devices. The ONS 15305 supports SNMP over IP, Telnet, and TFTP application protocols. To support management connectivity in any possible topology and application, the ONS 15305 supports management traffic on the following interfaces:
5.3.2.1 Management Port
The ONS 15305 has a dedicated Ethernet port for management, called the "Management Port." This port can be used for connecting to a craft terminal or for connecting to a separate external management network. The management port can be turned off to avoid unauthorized local access. The management port cannot be a member of a VLAN.
5.3.2.2 LAN Ports
The LAN ports are Ethernet ports used for connecting end customer IP traffic to the ONS 15305. The LAN ports can be members of VLANs that have IP addresses, or the LAN ports can have their own IP addresses. A LAN port can be used for carrying management traffic to and from the ONS 15305 if it is assigned to an IP address. This is called IP-Inband; some of the end-user IP bandwidth is used for management traffic.
5.3.2.3 WAN Ports
The WAN ports are device internal Ethernet ports that can be mapped into one or more VC-12s of an SDH STM-N signal. The WAN ports can be members of VLANs that have IP addresses, or the WAN ports can have their own IP addresses. A WAN port can be used for carrying management traffic to and from the ONS 15305 if it is assigned to an IP address. This is called IP-Inband; some of the end-user IP bandwidth is used for management traffic.
5.3.2.4 SDH Ports
The SDH architecture defines data communication channels (DCC) for transport of management traffic in the regenerator section (DCCR - 192 kbps) and in the multiplexer section (DCCM - 512 kbps).
The ONS 15305 supports the NSIF-DN-0101-001-R1 Draft Specification which defines IP in PPP over DCC.
The ONS 15305 also offers non-standard DCC communication that can be used in subnets of Cisco devices only. Ethernet frames are encapsulated in HDLC-like frames and sent on the DCC channel (i.e. not using CLNP and LAP-D). Both DCCR (Regenerator Section) and DCCM (Multiplexer Section) channels are supported.
Both DCC channels can be enabled on a port at the same time. Activation/deactivation of DCC channels is configurable on a per port basis. The maximum number of DCC channels that can be enabled in an ONS 15305 is eight.
5.3.2.5 Local VT-100 Serial Port
The local VT100 serial port provides the command line interface (CLI) for basic set-up of the ONS 15305. The port can also be accessed via Telnet.
5.3.3 Communication Features
5.3.3.1 IP-Forwarding
The IP-Forwarding implies that the device can have multiple IP interfaces, that is, it can be a multi-homed IP host. In addition, it is able to perform forwarding of IP datagrams between the interfaces, and the routing protocols (RIP, OSPF) are available. IP-Forwarding is software based and low capacity and is intended for management traffic only.
Typical use of IP-Forwarding is to support OSI Gateway functions and forwarding between the different management channels of a device.
IP-Forwarding is enabled by default in the ONS 15305.
5.3.3.2 IP-Routing
IP-Routing is a downloadable feature that can be enabled in the ONS 15305. By enabling the IP-Routing feature, all routing related functions are enabled in the device and the forwarding of IP datagrams between LAN/WAN ports are performed in hardware (Fast Forwarding Table). Forwarding of IP datagrams to and from the Management Port and DCC interfaces are still software based.
5.3.3.3 External DCN
This configuration is applicable for users connecting an IP-based DCN directly to the ONS 15305 or for connecting a craft terminal. For this type of connection, the management port is used. The configuration is described Figure 5-6.
Figure 5-6 Network Configuration
5.3.3.4 IP-Inband
IP-Inband means that LAN and WAN ports are carrying management traffic together with customer traffic. The configuration is described in Figure 5-7.
When using IP-Inband, the management traffic can be routed or switched using VLANs. If the traffic is routed, the routing is carried out in hardware (FFT) if IP-Routing is enabled. Otherwise, IP-Forwarding is used (software based).
Figure 5-7 Network Configuration
5.3.3.5 IP/PPP
IP/PPP means IP is carried in PPP on the SDH DCC channel according to NSIF-DN-0101-001. Typical configurations are described in Figure 5-8. When MSP is enabled, the management traffic over DCC follows the user traffic, that is, traffic is sent over the working and protect links but received only from the active link.
Figure 5-8 Network Configuration
5.3.3.6 IP/DCC
IP/DCC is a non-standard mechanism used for conveying management information on the SDH DCC channels in a network of Cisco devices only. This mechanism can be used together with the IP/DCC-Broadcast mechanism of other Cisco devices emulating a shared media on the SDH DCC channel. The IP datagrams are encapsulated in HDLC frames before being sent out on the SDH DCC.
This configuration is applicable for a user having a subnet of Cisco devices (with the ONS 15305 in the center) and an IP based DCN connected to the ONS 15305 management port. The configuration is described Figure 5-9.
Figure 5-9 Network Configuration
5.3.4 Management Security
The following security features apply to management communications.
5.3.4.1 CLI Access Control
User name and Password mechanisms.
5.3.4.2 SNMPv1 Access Control
For each user (SNMP Community), the following can be configured:
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5.3.4.3 Management Port Control
The Management Port can be enabled and disabled. This gives the operator control of the local access.
5.4 Alarm Definitions
The alarm and event definitions and their relations to the managed object types are listed in Table 5-3, Table 5-4, Table 5-5, and Table 5-6.
5.4.1 Clearable Alarms
5.4.2 Non-Clearable Alarms
5.4.3 Standard, Non-Clearable Alarms
5.4.4 Managed Objects and Related Events
5.5 Internet Index Reference Numbers
Table 5-8 DCC Channels Ethernet Indexes Numbers
Slot-1
1002 - 1017
Slot-2
1018 - 1033
Slot-3
1034 - 1049
Slot-4
1050 - 1065
Posted: Fri Sep 14 10:52:13 PDT 2007
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