Cisco ONS 15600 Reference Manual, Release 5.0
Chapter 6, Circuits
Downloads: This chapterpdf (PDF - 547.0KB) The complete bookPDF (PDF - 12.43MB) | Feedback

Circuits and Tunnels

Table Of Contents

Circuits and Tunnels

6.1  Overview

6.2  Circuit Properties

6.2.1  Concatenated STS Time Slot Assignments

6.2.2  Circuit Status

6.2.3  Circuit States

6.2.4  Circuit Protection Types

6.2.5  Circuit Information in the Edit Circuit Window

6.3  Cross-Connect Card Bandwidth

6.4  DCC Tunnels

6.4.1  Traditional DCC Tunnels

6.4.2  IP-Encapsulated Tunnels

6.5  Multiple Destinations for Unidirectional Circuits

6.6  Path Protection Circuits

6.7  Protection Channel Access Circuits

6.8  Path Trace

6.9  Automatic Circuit Routing

6.9.1  Bandwidth Allocation and Routing

6.9.2  Secondary Sources and Destination

6.10  Manual Circuit Routing

6.11  Constraint-Based Circuit Routing

6.12  Bridge and Roll

6.12.1  Rolls Window

6.12.2  Roll Status

6.12.3  Single and Dual Rolls

6.12.4  Two Circuit Bridge and Roll

6.12.5  Protected Circuits

6.13  Merge Circuits

6.14  Reconfigure Circuits


Circuits and Tunnels



Note The terms "Unidirectional Path Switched Ring" and "UPSR" may appear in Cisco literature. These terms do not refer to using Cisco ONS 15xxx products in a unidirectional path switched ring configuration. Rather, these terms, as well as "Protected Mesh Network" and "PPMN," refer generally to Cisco's path protection feature, which may be used in any topological network configuration. Cisco does not recommend using its path protection feature in any particular topological network configuration.


This chapter explains Cisco ONS 15600 synchronous transport signal (STS) circuits and data communications channel (DCC) and IP-encapsulated tunnels. To provision circuits and tunnels, refer to the Cisco ONS 15600 Procedure Guide.

Chapter topics include:

Overview

Circuit Properties

Cross-Connect Card Bandwidth

DCC Tunnels

Multiple Destinations for Unidirectional Circuits

Path Protection Circuits

Protection Channel Access Circuits

Path Trace

Automatic Circuit Routing

Manual Circuit Routing

Constraint-Based Circuit Routing

Bridge and Roll

Merge Circuits

Reconfigure Circuits


Note In this chapter, "cross-connect" and "circuit" have the following meanings: cross-connect refers to the connections that occur within a single ONS 15600 to allow a circuit to enter and exit an ONS 15600. Circuit refers to the series of connections from a traffic source (where traffic enters the ONS 15600 network) to the destination (where traffic exits an ONS 15600 network).


6.1  Overview

The ONS 15600 supports unidirectional and bidirectional circuits. Path protection or bidirectional line switched ring (BLSR) circuits can be revertive or nonrevertive. Circuits will route automatically or you can manually route them. The autorange feature eliminates the need to build circuits of the same type individually; the Cisco Transport Controller (CTC) can create up to five sequential circuits. You must specify the number of circuits that you need and build the first circuit.

You can provision circuits at either of the following points:

Before cards are installed. The ONS 15600 allows you to provision slot and circuits before installing the traffic cards.

After you preprovision the small-form factor pluggables (SFPs) (also called provisionable port modules [PPMs]).

Cards and SFPs are installed and ports are in service. Circuits do not actually carry traffic until the cards and SFPs are installed and the ports are In-Service and Normal (IS-NR); Out-of-Service and Autonomous, Automatic In-Service (OO-AU,AINS); or Out-of-Service and Management, Maintenance (OOS-MA,MT). Circuits will carry traffic as soon as the signal is received.

6.2  Circuit Properties

The ONS 15600 Circuits window (Figure 6-1), which is available from network, node, and card view, is where you can view information about circuits, including:

Name—The name of the circuit (user-assigned or automatically generated).

Type—For the ONS 15600, the circuit type is STS (STS circuit).

Size—The STS circuit size can be 1, 3c, 12c, 24c, 48c, or 192c. The STS circuit size for ASAP PPM ports also includes 6c and 9c. For time slot availability on concatenated STSs, see "Concatenated STS Time Slot Assignments" section.

Protection—The protection type; see the "Circuit Protection Types" section.

Direction—The circuit direction, either two-way or one-way.

Status—The circuit status; for details, see the "Circuit Status" section.

Source—The circuit source in the format: node/slot/port/STS. If an ASAP PPM port is the circuit source, the port format is PIM-PPM-port, where pluggable interface module (PIM) and PPM values are 1 through 4 (for example, p1-1-1). PPMs have only one port.

Destination—The circuit destination in the format: node/slot/port/STS. If an ASAP PPM port is the circuit destination, the port format is PIM-PPM-port, where PIM and PPM values are 1 through 4 (for example, p1-1-1). PPMs have only one port.

# of VLANS—(Future use.) The number of VLANs used by an Ethernet circuit.

# of Spans—The number of internode links that compose the circuit.

State—The circuit state; for details, see the "Circuit States" section.

Figure 6-1 ONS 15600 Circuit Window in Network View

The ONS 15600 supports up to 6144 STS-1 circuits. The Circuit Filter feature allows you to reduce the number of circuits that appear on the Circuits window. You can specify certain filter criteria, such as name, direction, and state; only the circuits that match the criteria will appear in the Circuits window.


Note You cannot set up VT circuits to terminate on an ONS 15600 node. However, you can create both STS and VT circuits that have an ONS 15454 or ONS 15327 source and destination with an ONS 15600 as a pass-through node. For information on VT circuit creation and tunneling, refer to the circuit chapters in the Cisco ONS 15327 Reference Manual and the Cisco ONS 15454 Reference Manual. Note that you cannot mix protection schemes, for example, 1+1 to path protection. Acceptable schemes are unprotected to unprotected, 1+1 to 1+1, BLSR to BLSR, and path protection to path protection.


6.2.1  Concatenated STS Time Slot Assignments

Table 6-1 shows the available time slot assignments for concatenated STSs when using CTC to provision circuits.

Table 6-1 STS Mapping Using CTC 

Starting STS
STS-3c
STS-6c
STS-9c
STS-12c
STS-24c
STS-48c
1

Yes

Yes

Yes

Yes

Yes

Yes

4

Yes

Yes

Yes

No

Yes

No

7

Yes

Yes

No

No

Yes

No

10

Yes

No

Yes

No

Yes

No

13

Yes

Yes

Yes

Yes

Yes

No

16

Yes

Yes

Yes

No

Yes

No

19

Yes

Yes

Yes

No

Yes

No

22

Yes

No

No

No

Yes

No

25

Yes

Yes

Yes

Yes

Yes

No

28

Yes

Yes

Yes

No

No

No

31

Yes

Yes

Yes

No

No

No

34

Yes

No

Yes

No

No

No

37

Yes

Yes

Yes

Yes

No

No

40

Yes

Yes

Yes

No

No

No

43

Yes

Yes

Yes

No

No

No

46

Yes

No

Yes

No

No

No

49

Yes

Yes

Yes

Yes

Yes

Yes

52

Yes

Yes

Yes

No

Yes

No

55

Yes

Yes

Yes

No

Yes

No

58

Yes

No

Yes

No

Yes

No

61

Yes

Yes

Yes

Yes

Yes

No

64

Yes

Yes

Yes

No

Yes

No

67

Yes

Yes

Yes

No

Yes

No

70

Yes

No

Yes

No

Yes

No

73

Yes

Yes

Yes

Yes

Yes

No

76

Yes

Yes

Yes

No

No

No

79

Yes

Yes

Yes

No

No

No

82

Yes

No

Yes

No

No

No

85

Yes

Yes

Yes

Yes

No

No

88

Yes

Yes

Yes

No

No

No

91

Yes

Yes

Yes

No

No

No

94

Yes

No

Yes

No

No

No

97

Yes

Yes

Yes

Yes

Yes

Yes

100

Yes

Yes

Yes

No

Yes

No

103

Yes

Yes

Yes

No

Yes

No

106

Yes

No

Yes

No

Yes

No

109

Yes

Yes

Yes

Yes

Yes

No

112

Yes

Yes

Yes

No

Yes

No

115

Yes

Yes

Yes

No

Yes

No

118

Yes

No

Yes

No

Yes

No

121

Yes

Yes

Yes

Yes

Yes

No

124

Yes

Yes

Yes

No

No

No

127

Yes

Yes

Yes

No

No

No

130

Yes

No

Yes

No

No

No

133

Yes

Yes

Yes

Yes

No

No

136

Yes

Yes

Yes

No

No

No

139

Yes

Yes

Yes

No

No

No

142

Yes

No

Yes

No

No

No

145

Yes

Yes

Yes

Yes

Yes

Yes

148

Yes

Yes

Yes

No

Yes

No

151

Yes

Yes

No

No

Yes

No

154

Yes

No

Yes

No

Yes

No

157

Yes

Yes

Yes

Yes

Yes

No

160

Yes

Yes

Yes

No

Yes

No

163

Yes

Yes

Yes

No

Yes

No

166

Yes

No

No

No

Yes

No

169

Yes

Yes

Yes

Yes

Yes

No

172

Yes

Yes

Yes

No

No

No

175

Yes

Yes

No

No

No

No

178

Yes

No

No

No

No

No

181

Yes

Yes

Yes

Yes

No

No

184

Yes

Yes

Yes

No

No

No

187

Yes

Yes

No

No

No

No

190

Yes

No

No

No

No

No


6.2.2  Circuit Status

The circuit statuses that appear in the Circuit window Status column are generated by CTC based on an assessment of conditions along the circuit path. Table 6-2 shows the statuses that can appear in the Status column.

Table 6-2 ONS 15600 Circuit Status 

Status
Definition/Activity

CREATING

CTC is creating a circuit.

DISCOVERED

CTC created a circuit. All components are in place and a complete path exists from circuit source to destination.

DELETING

CTC is deleting a circuit.

PARTIAL

A CTC-created circuit is missing a connection or circuit span (network link), a complete path from source to destination(s) does not exist, or a MAC address change occurred on one of the circuit nodes and the circuit is in need of repair (in the ONS 15454, the MAC address resides on the AIP; in the ONS 15600, the MAC address resides on the backplane EEPROM).

In CTC, circuits are represented using cross-connects and network spans. If a network span is missing from a circuit, the circuit status is PARTIAL. However, a PARTIAL status does not necessarily mean a circuit traffic failure has occurred, because traffic might flow on a protect path.

Network spans are in one of two states: up or down. On CTC circuit and network maps, up spans appear as green lines, and down spans appear as gray lines. If a failure occurs on a network span during a CTC session, the span remains on the network map but its color changes to gray to indicate that the span is down. If you restart your CTC session while the failure is active, the new CTC session cannot discover the span and its span line does not appear on the network map.

Subsequently, circuits routed on a network span that goes down appear as DISCOVERED during the current CTC session, but appear as PARTIAL to users who log in after the span failure.

DISCOVERED_TL1

A TL1-created circuit or a TL1-like, CTC-created circuit is complete. A complete path from source to destination(s) exists.

PARTIAL_TL1

A TL1-created circuit or a TL1-like, CTC-created circuit is missing a cross-connect or circuit span (network link), and a complete path from source to destination(s) does not exist.

CONVERSION_PENDING

An existing circuit in a topology upgrade is set to this state. The circuit returns to the DISCOVERED state when the topology upgrade is complete. For more information about topology upgrades, see Chapter 7, "SONET Topologies and Upgrades."

PENDING_MERGE

Any new circuits created to represent an alternate path in a topology upgrade are set to this status to indicate that it is a temporary circuit. These circuits can be deleted if a topology upgrade fails. For more information about topology upgrades, see Chapter 7, "SONET Topologies and Upgrades."

ROLL_PENDING

Roll is awaiting completion or cancellation. When a roll is in the ROLL PENDING state, you can complete a manual roll and cancel an automatic or manual roll.


6.2.3  Circuit States

The circuit service state is an aggregate of the cross-connect states within the circuit.

If all cross-connects in a circuit are in the IS-NR service state, the circuit service state is In-Service (IS).

If all cross-connects in a circuit are in the OOS-MA,MT; Out-of-Service and Autonomous, Automatic In-Service (OOS-AU,AINS); or Out-of-Service and Management, Disabled (OOS-MA,DSBLD) service state, the circuit service state is Out-of-Service (OOS).

PARTIAL is appended to the OOS circuit service state when circuit cross-connects state are mixed and not all in IS-NR. The OOS-PARTIAL state can occur during automatic or manual transitions between states. OOS-PARTIAL can appear during a manual transition caused by an abnormal event such as a CTC crash or communication error, or if one of the cross-connects could not be changed. Refer to the Cisco ONS 15600 Troubleshooting Guide for troubleshooting procedures.

You can assign a service state to circuit cross-connects at two points:

During circuit creation, you can set the state on the Create Circuit wizard.

After circuit creation, you can change a circuit state on the Edit Circuit window or from the Tools > Circuits > Set Circuit State menu.

During circuit creation, you can apply a service state to the drop ports in a circuit; however, CTC does not apply a requested state other than IS-NR to drop ports if:

The port is a timing source.

The port is provisioned for orderwire or tunnel orderwire.

The port is provisioned as a DCC or DCC tunnel.

The port supports 1+1 or BLSR.

Circuits do not use the soak timer, but ports do. The soak period is the amount of time that the port remains in the OOS-AU,AINS service state after a signal is continuously received. When the cross-connects in a circuit are in the OOS-AU,AINS service state, the ONS 15600 monitors the cross-connects for an error-free signal. It changes the state of the circuit from OOS to IS or to OOS-PARTIAL as each cross-connect assigned to the circuit path is completed. This allows you to provision a circuit using TL1, verify its path continuity, and prepare the port to go into service when it receives an error-free signal for the time specified in the port soak timer. For example, when assigning the IS,AINS administrative state to cross-connects in STS circuits, the circuit source and destination ports transition to the OOS-AU,AINS service state. When an alarm-free signal is received, the source and destination ports remain OOS-AU,AINS for the duration of the soak timer. After the port soak timer expires, STS source and destination ports change to IS-NR and the circuit service state to IS.

To find the remaining port soak time, choose the Maintenance > AINS Soak tabs in card view and click the Retrieve button. If the port is in the OOS-AU,AINS state and has a good signal, the Time Until IS column shows the soak count down status. If the port is OOS-AU,AINS and has a bad signal, the Time Until IS column indicates that the signal is bad. You must click the Retrieve button to obtain the latest time value.

For more information about cross-connect states, see Appendix B, "Administrative and Service States."

6.2.4  Circuit Protection Types

The Protection column on the Circuit window shows the card (line) and SONET topology (path) protection used for the entire circuit path. Table 6-3 lists the protection type indicators that you will see in this column.

Table 6-3 Circuit Protection Types 

Protection Type
Description

1+1

The circuit is protected by a 1+1 protection group.

2F BLSR

The circuit is protected by a 2-fiber BLSR.

2F-PCA

The circuit is routed on a protection channel access (PCA) path on a two-fiber BLSR. PCA circuits are unprotected.

DRI

The circuit is protected by dual-ring interconnection.

N/A

A circuit with connections on the same node is not protected.

Protected

The circuit is protected by diverse SONET topologies, for example a BLSR and a path protection, or a path protection and 1+1.

Unknown

A circuit has a source and destination on different nodes and communication is down between the nodes. This protection type appears if not all circuit components are known.

Unprot (black)

A circuit with a source and destination on different nodes is not protected.

Unprot (red)

A circuit created as a fully protected circuit is no longer protected due to a system change, such as removal of a BLSR or 1+1 protection group.

Path protection

The circuit is protected by a path protection.


6.2.5  Circuit Information in the Edit Circuit Window

When Show Detailed Map is checked in the Edit Circuit window, you can view information about ONS 15600 circuits. Routing information includes:

Circuit direction (unidirectional or bidirectional)

The nodes and STSs that the circuit traverses, including slots and port numbers

The circuit source and destination points

Open Shortest Path First (OSPF) area IDs

Link protection (path protection, unprotected, BLSR, 1+1) and bandwidth (OC-N)

For BLSRs, the detailed map shows the number of BLSR fibers and the BLSR ring ID. For path protection configurations, the map shows the active and standby paths from circuit source to destination, and it also shows the working and protect paths.

Alarms and states can also be viewed on the circuit map, including:

Alarm states of nodes on the circuit route

Number of alarms on each node organized by severity

Port service states on the circuit route

Alarm state/color of most severe alarm on port

Loopbacks

Path trace states

Path selector states

Figure 6-2 shows a bidirectional STS circuit routed on a path protection.

Figure 6-2 Path Protection Circuit on the Edit Circuit Window

By default, the working path is indicated by a green, bidirectional arrow, and the protect path is indicated by a purple, bidirectional arrow. Source and destination ports are shown as circles with an S and D, respectively. Port states are indicated by colors, shown in Table 6-4.

Table 6-4 Port State Color Indicators 

Port Color
Service State

Green

IS-NR

Gray

OOS-MA,DSBLD

Purple

OOS-AU,AINS

Cyan (Blue)

OOS-MA,MT


A notation within or by the squares in detailed view indicates switches and loopbacks, including:

F = Force switch

M = Manual switch

L = Lockout switch

Arrow = Facility (outward) or terminal (inward) loopback

Figure 6-3 shows an example of the Edit Circuit window with a terminal loopback.

Figure 6-3 Detailed Circuit Map Showing a Terminal Loopback

Move the mouse cursor over nodes, ports, and spans to see tooltips with information including the number of alarms on a node (organized by severity), a port's service state, and the protection topology.

Right-click a node, port, or span on the detailed circuit map to initiate certain circuit actions:

Right-click a unidirectional circuit destination node to add a drop to the circuit.

Right-click a port containing a path-trace-capable card to initiate the path trace.

Right-click a path protection span to change the state of the path selectors in the path protection circuit.

6.3  Cross-Connect Card Bandwidth

The single shelf cross-connect card (SSXC) cross-connect cards perform port-to-port, time-division multiplexing (TDM). The STS matrix has the capacity for 6144 STS terminations. Because each STS circuit requires a minimum of two terminations, one for ingress and one for egress, the SSXC has a capacity for 3072 STS circuits. However, this capacity is reduced at path protection and 1+1 nodes because three STS terminations are required at circuit source and destination nodes and four terminations are required at 1+1 circuit pass-through nodes. path protection pass-through nodes only require two STS terminations.

6.4  DCC Tunnels

SONET provides four data communications channels (DCCs) for network element operations, administration, maintenance, and provisioning: one on the SONET Section layer (DCC1) and three on the SONET Line layer (DCC2, DCC3, DCC4). The ONS 15600 uses the Section DCC (SDCC) for ONS 15600 management and provisioning. You can tunnel third-party SONET equipment across ONS 15600 networks using one of two tunneling methods, a traditional DCC tunnel or an IP-encapsulated tunnel.

6.4.1  Traditional DCC Tunnels

In traditional DCC tunnels, you can use the three Line DCCs (LDCCs) and the SDCC (when not used for ONS 15600 DCC terminations). A DCC tunnel endpoint is defined by slot, port, and DCC, where DCC can be either the SDCC or one of the LDCCs. You can link LDCCs to LDCCs and link SDCCs to SDCCs. You can also link an SDCC to an LDCC and an LDCC to an SDCC. To create a DCC tunnel, connect the tunnel endpoints from one ONS 15600 optical port to another. Table 6-5 lists the DCC tunnels that you can create.

Table 6-5 DCC Tunnels

DCC
SONET Layer
SONET Bytes

DCC1

Section

D1 to D3

DCC2

Line

D4 to D6

DCC3

Line

D7 to D9

DCC4

Line

D10 to D12


When you create DCC tunnels, keep the following guidelines in mind:

Each ONS 15600 can have up to 64 DCC tunnel connections.

An SDCC that is terminated cannot be used as a DCC tunnel endpoint.

An SDCC that is used as an DCC tunnel endpoint cannot be terminated.

All DCC tunnel connections are bidirectional.

6.4.2  IP-Encapsulated Tunnels

An IP-encapsulated tunnel puts an SDCC in an IP packet at a source node and dynamically routes the packet to a destination node. To compare traditional DCC tunnels with IP-encapsulated tunnels, a traditional DCC tunnel is configured as one dedicated path across a network and does not provide a failure recovery mechanism if the path is down. An IP-encapsulated tunnel is a virtual path, which adds protection when traffic travels between different networks.

IP-encapsulated tunneling has the potential of flooding the DCC network with traffic resulting in a degradation of performance for CTC. The data originating from an IP tunnel can be throttled to a user-specified rate, which is a percentage of the total SDCC bandwidth.

Each ONS 15600 supports up to 128 IP-encapsulated tunnels. You can convert a traditional DCC tunnel to an IP-encapsulated tunnel or an IP-encapsulated tunnel to a traditional DCC tunnel. Only tunnels in the DISCOVERED status can be converted.


Caution Converting from one tunnel type to the other is service-affecting.

6.5  Multiple Destinations for Unidirectional Circuits

Unidirectional circuits can have multiple destinations (drops) for use in broadcast circuit schemes. In broadcast scenarios, one source transmits traffic to multiple destinations, but traffic is not returned to the source. The ONS 15600 supports one of the following:

Up to 2048 1:2 nonblocking broadcast connections

Up to 682 1:n nonblocking broadcast connections (where n is less than or equal to 8)

When you create a unidirectional circuit, the card that does not have its backplane receive (Rx) input terminated with a valid input signal generates a Loss of Signal (LOS) alarm. To mask the alarm, create an alarm profile suppressing the LOS alarm and apply the profile to the port that does not have its Rx input terminated. To create an alarm profile, refer to the "Manage Alarms" chapter in the Cisco ONS 15600 Procedure Guide.

6.6  Path Protection Circuits

Use the Edit Circuit window to change path protection selectors and switch protection paths (Figure 6-4). In the UPSR Selectors subtab on the Edit Circuits window, you can:

View the path protection circuit's working and protection paths.

Edit the reversion time.

Set the hold-off timer.

Edit the Signal Fail (SF) and Signal Degrade (SD) thresholds.

Change Path Payload Defect Indication (PDI-P) settings.


Note In the UPSR Selectors tab, the SF Ber Level and SD Ber Level columns display "N/A" for those nodes that do not support VT signal bit error rate (BER) monitoring. In Software Release 5.0, only the Cisco ONS 15310-CL supports VT signal BER monitoring.


From the UPSR Switch Counts subtab, you can:

Perform maintenance switches on the circuit selector.

View switch counts for the selectors.

Figure 6-4 Editing Path Protection Selectors

On the UPSR Switch Counts tab, you can view switch counts for the selectors (Figure 6-5).

Figure 6-5 Viewing Path Protection Switch Counts

If ONS 15600s are connected to a third-party network, you can create an open-ended path protection circuit to route a circuit through it. To do this, you create three circuits. One circuit is created on the source ONS 15600 network. This circuit has one source and two destinations, one at each ONS 15600 that is connected to the third-party network. The second circuit is created on the third-party network so that the circuit travels across the network on two paths to the ONS 15600s. That circuit routes the two circuit signals across the network to ONS 15600s that are connected to the network on other side. At the destination node network, the third circuit is created with two sources, one at each node connected to the third-party network. A selector at the destination node chooses between the two signals that arrive at the node, similar to a regular path protection circuit.

6.7  Protection Channel Access Circuits

You can provision circuits to carry traffic on BLSR protection channels when conditions are fault-free and set up BLSR diagnostic test circuits. Traffic routed on BLSR PCA circuits, called extra traffic, has lower priority than the traffic on the working channels and has no means for protection. During ring or span switches, PCA circuits are preempted and squelched. For example, in a two-fiber OC-48 BLSR, STSs 25 to 48 can carry extra traffic when no ring switches are active, but PCA circuits on these STSs are preempted when a ring switch occurs. When the conditions that caused the ring switch are remedied and the ring switch is removed, PCA circuits are restored. If the BLSR is provisioned as revertive, this occurs automatically after the fault conditions are cleared and the reversion timer has expired.

Traffic provisioning on BLSR protection channels is performed during circuit provisioning. The Protection Channel Access check box appears whenever Fully Protected Path is unchecked on the circuit creation wizard. Refer to the Cisco ONS 15600 Procedure Guide for more information. When provisioning PCA circuits, two considerations are important to keep in mind:

If BLSRs are provisioned as nonrevertive, PCA circuits are not restored automatically after a ring or span switch. You must switch the BLSR manually.

PCA circuits are routed on working channels when you upgrade a BLSR from one optical speed to a higher optical speed. For example, if you upgrade a two-fiber OC-48 BLSR to an OC-192, STSs 25 to 48 on the OC-48 BLSR become working channels on the OC-192 BLSR.

6.8  Path Trace

SONET J1 path trace is a repeated, fixed-length string that includes 64 consecutive J1 bytes. You can use the string to monitor interruptions or changes to circuit traffic. If the string received at a circuit drop port does not match the string the port expects to receive, the Trace Identifier Mismatch Path (TIM-P) alarm is raised. The ONS 15600 can also monitor a 16-byte ITU pattern.

Table 6-6 lists the ONS 15600 cards that support path trace.

Table 6-6 ONS 15600 Cards Supporting J1 Path Trace

Card
Receive
Transmit

OC48/STM16 SR/SH 16 Port 1310

Yes

No

OC48/STM16 LR/LH 16 Port 1550

Yes

No

OC192/STM64 SR/SH 4 Port 1310

Yes

No

OC192/STM64 LR/LH 4 Port 1550

Yes

No

ASAP OC-N PPMs

Yes

No

ASAP Ethernet PPMs

Yes

Yes


The ONS 15600 supports both automatic and manual J1 path trace monitoring to detect and report the contents of the 64-byte STS path trace message (nonterminated) for the designated STS path.

Automatic—The receiving port assumes that the first J1 string it receives is the baseline J1 string.

Manual—The receiving port uses a string that you manually enter as the baseline J1 string.

6.9  Automatic Circuit Routing

If you select automatic routing during circuit creation, CTC routes the circuit by dividing the entire circuit route into segments based on protection domains. For unprotected segments of circuits provisioned as fully protected, CTC finds an alternate route to protect the segment, creating a virtual path protection. Each segment of a circuit path is a separate protection domain. Each protection domain is protected in a specific protection scheme including card protection (1+1) or SONET topology (path protection or BLSR).

The following list provides principles and characteristics of automatic circuit routing:

Circuit routing tries to use the shortest path within the user-specified or network-specified constraints.

If you do not choose fully path protected during circuit creation, circuits can still contain protected segments. Because circuit routing always selects the shortest path, one or more links and/or segments can have some protection. CTC does not look at link protection while computing a path for unprotected circuits.

Circuit routing does not use links that are down. If you want all links to be considered for routing, do not create circuits when a link is down.

Circuit routing computes the shortest path when you add a new drop to an existing circuit. It tries to find the shortest path from the new drop to any nodes on the existing circuit.

6.9.1  Bandwidth Allocation and Routing

Within a given network, CTC routes circuits on the shortest possible path between source and destination based on the circuit attributes, such as protection and type. CTC considers using a link for the circuit only if the link meets the following requirements:

The link has sufficient bandwidth to support the circuit.

The link does not change the protection characteristics of the path.

The link has the required time slots to enforce the same time slot restrictions for BLSR.

If CTC cannot find a link that meets these requirements, an error appears.

6.9.2  Secondary Sources and Destination

CTC supports secondary sources and destinations (drops). Secondary sources and destinations typically interconnect two third-party networks, as shown in Figure 6-6. Traffic is protected while it traverses a network of ONS 15600s.

Figure 6-6 Secondary Sources and Drops

Several rules apply to secondary sources and destinations:

CTC does not allow a secondary destination for unidirectional circuits because you can specify additional destinations after you create the circuit.

Primary and secondary sources should be on the same node.

Primary and secondary destinations should be on the same node.

Secondary sources and destinations are permitted only for regular STS connections.

For bidirectional circuits, CTC creates a path protection connection at the source node that allows traffic to be selected from one of the two sources on the ONS 15600 network. If you check the Fully Path Protected option during circuit creation, traffic is protected within the ONS 15600 network. At the destination, another path protection connection is created to bridge traffic from the ONS 15600 network to the two destinations. A similar but opposite path exists for the reverse traffic flowing from the destinations to the sources.

For unidirectional circuits, a path protection drop-and-continue connection is created at the source node.

6.10  Manual Circuit Routing

Routing circuits manually allows you to:

Choose a specific path, not just the shortest path chosen by automatic routing.

Choose a specific STS on each link along the route.

CTC imposes the following rules on manual routes:

All circuits in a shared packet ring should have links with a direction that flows from source to destination.

If you enabled Fully Protected Path, choose a diverse protect (alternate) path for every unprotected segment.

For a node that has a path protection selector based on the links chosen, the input links to the path protection selectors cannot be 1+1 protected. The same rule applies at the path protection bridge.

If you enabled Fully Protected Path, CTC verifies that the route selection is protected at all segments. A route can have multiple protection domains with each domain protected by a different scheme.

Table 6-7 summarizes the available bidirectional connections. Any other combination is invalid and generates an error.

Table 6-7 Bidirectional STS Circuits 

No. of Inbound Links
No. of Outbound Links
No. of Sources
No. of Drops
Connection Type

2

1

Path protection

2

1

Path protection

2

1

Path protection

1

2

Path protection

1

2

Path protection

1

2

Path protection

2

2

Double path protection

2

2

Double path protection

2

2

Double path protection

1

1

Two-way


Table 6-8 summarizes the available unidirectional connections. Any other combination is invalid and generates an error.

Table 6-8 Unidirectional STS Circuits

No. of Inbound Links
No. of Outbound Links
No. of Sources
No. of Drops
Connection Type

1

1

One-way

1

2

Path protection head end

2

1

Path protection head end

2

1+

Path protection drop and continue


6.11  Constraint-Based Circuit Routing

When you create circuits, you can choose Fully Protected Path to protect the circuit from source to destination. The protection mechanism used depends on the path that CTC calculates for the circuit. If the network is comprised entirely of BLSR or 1+1 links, or the path between source and destination can be entirely protected using 1+1 or BLSR links, no path-protected mesh network (PPMN), or virtual path protection, protection is used.

If PPMN protection is needed to protect the path, set the level of node diversity for the PPMN portions of the complete path on the Circuit Routing Preferences area of the Circuit Creation dialog box:

Nodal Diversity Required—Ensures that the primary and alternate paths of each PPMN domain in the complete path have a diverse set of nodes.

Nodal Diversity Desired—CTC looks for a node-diverse path; if a node-diverse path is not available, CTC finds a link-diverse path for each PPMN domain in the complete path.

Link Diversity Only—Creates only a link diverse path for each PPMN domain.

When you choose automatic circuit routing during circuit creation, you have the option to require or exclude nodes and links in the calculated route. You can use this option to achieve the following results:

Simplify manual routing, especially if the network is large and selecting every span is tedious. You can select a general route from source to destination and allow CTC to fill in the route details.

Balance network traffic; by default CTC chooses the shortest path, which can load traffic on certain links while other links are either free or use less bandwidth. By selecting a required node and/or a link, you force CTC to use (or not use) an element, resulting in more efficient use of network resources.

CTC considers required nodes and links to be an ordered set of elements. CTC treats the source nodes of every required link as required nodes. When CTC calculates the path, it makes sure the computed path traverses the required set of nodes and links and does not traverse excluded nodes and links.

The required nodes and links constraint is used only during the primary path computation and only for PPMN domains/segments. The alternate path is computed normally; CTC uses excluded nodes/links when finding all primary and alternate paths on PPMNs.

6.12  Bridge and Roll

The CTC Bridge and Roll wizard reroutes live traffic without interrupting service. The bridge process takes traffic from a designated "roll from" facility and establishes a cross-connect to the designated "roll to" facility. When the bridged signal at the receiving end point is verified, the roll process creates a new cross-connect to receive the new signal. When the roll completes, the original cross-connects are released. You can use the bridge and roll feature for maintenance functions such as card or facility replacement, or for load balancing.


Note To perform bridge and roll, you should be logged into an ONS 15600 node. If you are logged into an ONS 15454 or ONS 15327 node, you should log out. When you log in, clear the cache and reload CTC from an ONS 15600 node.


6.12.1  Rolls Window

The Rolls window lists information about a rolled circuit before the roll process is complete. You can access the Rolls window by clicking the Circuits > Rolls tabs in either network or node view. Figure 6-7 shows the Rolls window.

Figure 6-7 Rolls Window

The Rolls window information includes:

Roll From Circuit—The circuit that has connections that will no longer be used when the roll process is complete.

Roll To Circuit—The circuit that will carry the traffic once the roll process is complete. The Roll To Circuit is the same as the Roll From Circuit if a single circuit is involved in a roll.

Roll State—The roll status; see the "Roll Status" section.

Roll Mode—The mode indicates whether the roll is automatic or manual. CTC implements the roll mode at the cross-connect level, which means it applies to connections within a single ONS 15600.

Automatic—When a valid signal is received on the new path, CTC completes the roll on the node automatically. You can cancel an automatic roll only when the Roll Valid Signal value is false. One-way source rolls are always automatic.

Manual—You must complete a manual roll after a valid signal is received. You can cancel a manual roll at any time. One-way destination rolls are always manual. Use the Complete button to terminate a manual roll. You can do this when a manual roll is in a ROLL_PENDING status and you have not yet completed the roll or have not cancelled its sibling roll.

Roll Path—The fixed point of the roll object.

Roll From Path— The path (STS) that is being rerouted.

Roll To Path—The new path where the Roll From Path is rerouted.

The Finish button completes the circuit processing of a roll and changes the circuit status from ROLL_PENDING to DISCOVERED. To prevent a roll, use the Cancel button. You can cancel a manual roll at anytime; you can cancel an automatic roll only if the Roll Valid Signal is false.

6.12.2  Roll Status

Table 6-9 lists the roll statuses.

Table 6-9 Roll Statuses

State
Description

ROLL_PENDING

Roll is awaiting completion or cancellation

ROLL_CANCELLED

Roll has been canceled



Note You can only reroute circuits in the DISCOVERED status. You cannot reroute circuits that are in the ROLL_PENDING status.


6.12.3  Single and Dual Rolls

Circuits have an additional layer of roll types: single and dual. A single roll on a circuit is a roll on one of its cross-connects. Use a single roll to:

Change either the source or destination of a selected circuit (Figure 6-8 and Figure 6-9, respectively).

Roll a segment of the circuit onto another chosen circuit (Figure 6-10). This roll also results in a new destination.

In Figure 6-8, you can select any available STS on Node 1 for a new source.

Figure 6-8 Single Source Roll

In Figure 6-9, you can select any available STS on Node 2 for a new destination.

Figure 6-9 Single Destination Roll

Figure 6-10 shows one circuit rolling onto another circuit. The new circuit has cross-connects on Node 1, Node 3, and Node 4. CTC deletes the cross-connect on Node 2 after the roll.

Figure 6-10 Single Roll from One Circuit to Another Circuit

A dual roll involves two cross-connects. It allows you to reroute intermediate segments of a circuit, but keep the original source and destination. You can perform a dual roll on a single circuit or two circuits. When rolling two cross-connects using the Bridge and Roll wizard, you can choose an existing circuit or create a new circuit. The created circuit has the same name as the original circuit with the suffix _ROLL**.

Dual rolls have several constraints:

You must complete or cancel both cross-connects rolled in a dual roll. You cannot complete one roll and cancel the other roll.

When a Roll To circuit is involved in the dual roll, the first roll must roll onto the source of the Roll To circuit and the second roll must roll onto the destination of the Roll To circuit.

Figure 6-11 illustrates a dual roll on the same circuit.

Figure 6-11 Dual Roll on the Same Circuit

Figure 6-12 illustrates a dual roll involving two circuits.

Figure 6-12 Dual Roll on Two Circuits

6.12.4  Two Circuit Bridge and Roll

When using the bridge and roll feature to reroute traffic using two circuits, the following constraints apply:

DCC must be enabled on the circuits involved in a roll before roll creation.

A maximum of two rolls can exist between any two circuits.

If two rolls are involved between two circuits, both rolls must be on the original circuit. The second circuit should not carry live traffic. The two rolls loop from the second circuit back to the original circuit. The roll mode of the two rolls must be identical (either automatic or manual).

If a single roll exists on a circuit, you must roll the connection onto the source or the destination of the second circuit and not an intermediate node in the circuit.

6.12.5  Protected Circuits

CTC allows you to roll the working or protect path regardless of which path is active. You can upgrade an unprotected circuit to a fully protected circuit or downgrade a 1+1 protected circuit to an unprotected circuit. When using bridge and roll on path protection circuits, you can roll the source or destination or both path selectors in a dual roll. However, you cannot roll a single path selector. You can also perform bridge and roll on BLSR circuits.

6.13  Merge Circuits

A circuit merge combines a single selected circuit with one or more circuits. You can merge tunnels, CTC-created circuits, and TL1-created circuits. To merge circuits, you choose a circuit on the CTC Circuits window and the circuits that you want to merge with the chosen (master) circuit on the Merge tab in the Edit Circuit window. The Merge tab shows only the circuits that are available for merging with the master circuit:

Circuit cross-connects must create a single, contiguous path.

Circuits types must be a compatible.

Circuit directions must be compatible. You can merge a one-way and a two-way circuit, but not two one-way circuits in opposing directions.

Circuit sizes must be identical.

Circuit end points must send or receive the same framing format.

The merged circuits must become a DISCOVERED circuit.

If all connections from the master circuit and all connections from the merged circuits align to form one complete circuit, the merge is successful. If all connections from the master circuit and some, but not all, connections from the other circuits align to form a single complete circuit, CTC notifies you and gives you the chance to cancel the merge process. If you choose to continue, the aligned connections merge successfully into the master circuit, and unaligned connections remain in the original circuits.

All connections from the master circuit and at least one connection from the other selected circuits must be used in the resulting circuit for the merge to succeed. If a merge fails, the master circuit and all other circuits remain unchanged. When the circuit merge completes successfully, the resulting circuit retains the name of the master circuit.

6.14  Reconfigure Circuits

You can reconfigure multiple circuits, which is typically necessary when a large number of circuits are in the PARTIAL status. When you reconfigure multiple circuits, the selected circuits can be any combination of DISCOVERED, PARTIAL, DISCOVERED_TL1, and PARTIAL_TL1 circuits. You can reconfigure tunnels, CTC-created circuits, and TL1-created circuits.

Use the CTC Tools > Circuits > Reconfigure Circuits command to reconfigure selected circuits. During reconfiguration, CTC reassembles all connections of the selected circuits into circuits based on path size, direction, and alignment. Some circuits might merge and others might split into multiple circuits. If the resulting circuit is a valid circuit, it appears as a DISCOVERED circuit. Otherwise, the circuit appears as a PARTIAL or PARTIAL_TL1 circuit.


Note PARTIAL tunnel circuits do not split into multiple circuits during reconfiguration.