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Table Of Contents
10.2.1 Concatenated STS Time Slot Assignments
10.2.4 Circuit Protection Types
10.2.5 Circuit Information in the Edit Circuit Window
10.3 Cross-Connect Card Bandwidth
10.5.1 Traditional DCC Tunnels
10.5.2 IP-Encapsulated Tunnels
10.6 Multiple Destinations for Unidirectional Circuits
10.8.1 Open-Ended Path Protection Circuits
10.8.2 Go-and-Return Path Protection Routing
10.9 BLSR Protection Channel Access Circuits
10.11 Path Signal Label, C2 Byte
10.12 Automatic Circuit Routing
10.12.1 Bandwidth Allocation and Routing
10.12.2 Secondary Sources and Destination
10.14 Constraint-Based Circuit Routing
10.15 Virtual Concatenated Circuits
10.15.2 Link Capacity Adjustment
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 "Path 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 15454 synchronous transport signal (STS), virtual tributary (VT), and virtual concatenated (VCAT) circuits and VT, data communications channel (DCC), and IP-encapsulated tunnels. To provision circuits and tunnels, refer to the Cisco ONS 15454 Procedure Guide.
Chapter topics include:
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10.1 Overview
You can create circuits across and within ONS 15454 nodes and assign different attributes to circuits. For example, you can:
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You can provision circuits at any of the following points:
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10.2 Circuit Properties
The ONS 15454 Circuits window, which appears in network, node, and card view, is where you can view information about circuits. The Circuits window ( Figure 10-1) provides the following information:
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Figure 10-1 ONS 15454 Circuit Window in Network View
10.2.1 Concatenated STS Time Slot Assignments
Table 10-1 shows the available time slot assignments for concatenated STSs when using Cisco Transport Controller (CTC) to provision circuits.
10.2.2 Circuit Status
The circuit statuses that appear in the Circuit window Status column are generated by CTC based on conditions along the circuit path. Table 10-2 shows the statuses that can appear in the Status column.
Table 10-2 ONS 15454 Circuit Status
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 cross-connect or network span, a complete path from source to destinations does not exist, or an alarm interface panel (AIP) change occurred on one of the circuit nodes and the circuit is in need of repair. (AIPs store the node MAC address.)
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, an 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 destinations 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 destinations does not exist.
CONVERSION_PENDING
An existing circuit in a topology upgrade is set to this state. The circuit returns to the DISCOVERED state once the topology upgrade is complete. For more information about topology upgrades, see Chapter 11, "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 11, "SONET Topologies and Upgrades."
10.2.3 Circuit States
The circuit service state is an aggregate of the cross-connect states within the circuit.
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The state of a VCAT circuit is an aggregate of its member circuits. An In Group member has cross-connects in the IS-NR; OOS-MA,AINS; or OOS-MA,MT service states. An Out of Group member has cross-connects in the OOS-MA,DSBLD or OOS-MA,OOG service states. You can view whether a VCAT member is In Group or Out of Group in the VCAT State column on the Edit Circuits window.
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You can assign a state to circuit cross-connects at two points:
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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:
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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 15454 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. Two common examples of state changes you see when provisioning circuits using CTC are:
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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 port and cross-connect states, see "Administrative and Service States."
10.2.4 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 10-3 shows the protection type indicators that appear in this column.
10.2.5 Circuit Information in the Edit Circuit Window
The detailed circuit map on the Edit Circuit window allows you to view information about ONS 15454 circuits. Routing information that appears includes:
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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. The map indicates nodes set up as dual-ring interconnect nodes. For VCAT circuits, the detailed map is not available for an entire VCAT circuit. However, you can view the detailed map to view the circuit route for each individual member.
You can also view alarms and states on the circuit map, including:
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Figure 10-2 shows a VT circuit routed on a four-fiber BLSR.
Figure 10-2 BLSR Circuit Displayed on the Detailed Circuit Map
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. Port states are indicated by colors, shown in Table 10-4.
Table 10-4 Port State Color Indicators
Green
IS-NR
Gray
OOS-MA,DSBLD
Violet
OOS-AU,AINS
Blue (Cyan)
OOS-MA,MT
A notation within or by the squares in detailed view indicates switches and loopbacks, including:
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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), port service state, and the protection topology.
Right-click a node, port, or span on the detailed circuit map to initiate certain circuit actions:
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Figure 10-3 shows an example of the information that can appear. From this example, you can determine:
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From the example, you could:
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Figure 10-3 Detailed Circuit Map Showing a Terminal Loopback
10.3 Cross-Connect Card Bandwidth
The ONS 15454 XCVT and XC10G cross-connect cards perform port-to-port, time-division multiplexing (TDM). XCVT and XC10G cards perform STS and VT1.5 multiplexing.
The STS matrix on the XCVT cross-connect card has a capacity for 288 STS terminations, and the XC10G has a capacity for 1152 STS terminations. Because each STS circuit requires a minimum of two terminations, one for ingress and one for egress, the XCVT has a capacity for 144 STS circuits, and the XC10G has a capacity for 576 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.
The XCVT and XC10G cards perform VT1.5 multiplexing through 24 logical STS ports on the XCVT or XC10G VT matrix. Each logical STS port can carry 28 VT1.5s. Subsequently, the VT matrix has capacity for 672 VT1.5s terminations, or 336 VT1.5 circuits, because every circuit requires two terminations, one for ingress and one for egress. However, this capacity is only achievable if:
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For example, if you create a VT1.5 circuit from STS-1 on a drop card and a second VT1.5 circuit from STS-2, two VT matrix STS ports are used, as shown in Figure 10-4. If you create a second VT1.5 circuit from the same STS port on the drop card, no additional logical STS ports are used on the VT matrix. However, if the next VT1.5 circuit originates on a different STS, a second STS port on the VT matrix is used, as shown in Figure 10-5. If you continued to create VT1.5 circuits on different EC-1 STSs and mapped each to an unused outbound STS, the VT matrix capacity would be reached after you created 12 VT1.5 circuits.
Figure 10-4 One VT1.5 Circuit on One STS
Figure 10-5 Two VT1.5 Circuits in a BLSR
Note
VT matrix capacity is also affected by SONET protection topology and node position within the circuit path. Matrix usage is slightly higher for path protection nodes than BLSR and 1+1 nodes. Circuits use two VT matrix ports at pass-through nodes if VT tunnels and aggregation points are not used. If the circuit is routed on a VT tunnel or an aggregation point, no VT matrix resources are used. Table 10-5 shows basic STS port usage rates for VT 1.5 circuits.
Cross-connect card resources can be viewed on the Maintenance > Cross-Connect > Resource Usage tabs. This tab shows:
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To maximize resources on the cross-connect card VT matrix, keep the following points in mind as you provision circuits:
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10.4 Portless Transmux
The DS3XM-12 card provides a portless transmux interface to change DS-3s into VT1.5s. For XCVT drop slots, the DS3XM-12 card provides a maximum of 6 portless transmux interfaces; for XCVT trunk slots and XC10G any slots, the DS3XM-12 card provides a maximum of 12 portless transmux interfaces. If a pair of ports are configured as portless transmux, CTC allows you to create a DS3/STS1 circuit using one of these ports as the circuit end point. You can create separate DS1/VT1.5 circuits (up to 28) using the other port in this portless transmux pair.
When creating a circuit through the DS3XM-12 card, the portless pair blocks the mapped physical port(s); CTC does not display a blocked physical port in the source or destination drop-down list during circuit creation. Table 10-6 lists the portless transmux mapping for XCVT drop ports.
Table 10-6 Portless Transmux Mapping for XCVT Drop Ports
1, 2
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15, 16
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Table 10-7 lists the portless transmux for XCVT trunk ports and XC10G any-slot ports.
10.5 DCC Tunnels
SONET provides four DCCs for network element operation, administration, maintenance, and provisioning: one on the SONET Section layer (DCC1) and three on the SONET Line layer (DCC2, DCC3, and DCC4). The ONS 15454 uses the Section DCC (SDCC) for ONS 15454 management and provisioning. An SDCC and Line DCC (LDCC) each provide 192 Kbps of bandwidth per channel. The aggregate bandwidth of the three LDCCs is 576 Kbps. When multiple DCC channels exist between two neighboring nodes, the ONS 15454 balances traffic over the existing DCC channels using a load balancing algorithm. This algorithm chooses a DCC for packet transport by considering packet size and DCC utilization. You can tunnel third-party SONET equipment across ONS 15454 networks using one of two tunneling methods: a traditional DCC tunnel or an IP-encapsulated tunnel.
10.5.1 Traditional DCC Tunnels
In traditional DCC tunnels, you can use the three LDCCs and the SDCC (when not used for ONS 15454 DCC terminations). A traditional 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 a SDCC to an LDCC, and a LDCC to a SDCC. To create a DCC tunnel, you connect the tunnel endpoints from one ONS 15454 optical port to another. Cisco recommends a maximum of 84 DCC tunnel connections for an ONS 15454. Table 10-8 shows the DCC tunnels that you can create using different OC-N cards.
Figure 10-6 shows a DCC tunnel example. Third-party equipment is connected to OC-3 cards at Node 1/Slot 3/Port 1 and Node 3/Slot 3/Port 1. Each ONS 15454 node is connected by OC-48 trunk (span) cards. In the example, three tunnel connections are created, one at Node 1 (OC-3 to OC-48), one at Node 2 (OC-48 to OC-48), and one at Node 3 (OC-48 to OC-3).
Figure 10-6 Traditional DCC Tunnel
When you create DCC tunnels, keep the following guidelines in mind:
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10.5.2 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 15454 supports up to ten 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
10.6 Multiple Destinations for Unidirectional Circuits
Unidirectional circuits can have multiple destinations for use in broadcast circuit schemes. In broadcast scenarios, one source transmits traffic to multiple destinations, but traffic is not returned to the source.
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.
10.7 Monitor Circuits
Monitor circuits are secondary circuits that monitor traffic on primary bidirectional circuits. Figure 10-7 shows an example of a monitor circuit. At Node 1, a VT1.5 is dropped from Port 1 of an EC1-12 card. To monitor the VT1.5 traffic, plug test equipment into Port 2 of the EC1-12 card and provision a monitor circuit to Port 2. Circuit monitors are one-way. The monitor circuit in Figure 10-7 monitors VT1.5 traffic received by Port 1 of the EC1-12 card.
Figure 10-7 VT1.5 Monitor Circuit Received at an EC1-12 Port
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10.8 Path Protection Circuits
Use the Edit Circuits window to change path protection selectors and switch protection paths ( Figure 10-8). In the UPSR Selectors subtab on the Edit Circuits window, you can:
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In the UPSR Switch Counts subtab, you can:
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Figure 10-8 Editing Path Protection Selectors
10.8.1 Open-Ended Path Protection Circuits
If ONS 15454s 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 15454 network. This circuit has one source and two destinations, one at each ONS 15454 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 15454s. That circuit routes the two circuit signals across the network to ONS 15454s 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.
10.8.2 Go-and-Return Path Protection Routing
The go-and-return path protection routing option allows you to route the path protection working path on one fiber pair and the protect path on a separate fiber pair ( Figure 10-9). The working path will always be the shortest path. If a fault occurs, both the working and protection fibers are not affected. This feature only applies to bidirectional path protection circuits. The go-and-return option appears on the Circuit Attributes panel of the Circuit Creation wizard.
Figure 10-9 Path Protection Go-and-Return Routing
10.9 BLSR Protection Channel Access Circuits
You can provision circuits to carry traffic on BLSR protection channels when conditions are fault-free. 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 25-48 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 15454 Procedure Guide for more information. When provisioning PCA circuits, two considerations are important to keep in mind:
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10.10 Path Trace
SONET J1 and J2 path trace are repeated, fixed-length strings composed of 64 consecutive bytes. You can use the strings to monitor interruptions or changes to circuit traffic.
Table 10-9 shows the ONS 15454 cards that support J1 path trace. DS-1 and DS-3 cards can transmit and receive the J1 field, while the EC-1, OC-3, OC-48 AS, and OC-192 can only receive the J1 bytes. Cards that are not listed in the table do not support the J1 byte. The DS3XM-12 card supports J2 path trace for VT circuits.
If the string received at a circuit drop port does not match the string the port expects to receive, an alarm is raised. Two path trace modes are available:
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10.11 Path Signal Label, C2 Byte
One of the overhead bytes in the SONET frame is the C2 byte. The SONET standard defines the C2 byte as the path signal label. The purpose of this byte is to communicate the payload type being encapsulated by the STS path overhead (POH). The C2 byte functions similarly to EtherType and Logical Link Control (LLC)/Subnetwork Access Protocol (SNAP) header fields on an Ethernet network; it allows a single interface to transport multiple payload types simultaneously. C2 byte hex values are provided in Table 10-10.
If a circuit is provisioned using a terminating card, the terminating card provides the C2 byte. A VT circuit is terminated at the XCVT or XC10G card, which generates the C2 byte (0x02) downstream to the STS terminating cards. The XCVT or XC10G card generates the C2 value (0x02) to the DS1 or DS3XM terminating card. If an optical circuit is created with no terminating cards, the test equipment must supply the path overhead in terminating mode. If the test equipment is in pass-through mode, the C2 values usually change rapidly between 0x00 and 0xFF. Adding a terminating card to an optical circuit usually fixes a circuit having C2 byte problems. Table 10-11 lists label assignments for signals with payload defects.
10.12 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, 1:1, etc.) or SONET topology (path protection, BLSR, etc.).
The following list provides principles and characteristics of automatic circuit routing:
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10.12.1 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:
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If CTC cannot find a link that meets these requirements, an error appears.
The same logic applies to VT circuits on VT tunnels. Circuit routing typically favors VT tunnels because VT tunnels are shortcuts between a given source and destination. If the VT tunnel in the route is full (no more bandwidth), CTC asks whether you want to create an additional VT tunnel.
10.12.2 Secondary Sources and Destination
CTC supports secondary circuit sources and destinations (drops). Secondary sources and destinations typically interconnect two third-party networks, as shown in Figure 10-10. Traffic is protected while it goes through a network of ONS 15454s.
Figure 10-10 Secondary Sources and Destinations
Several rules apply to secondary sources and destinations:
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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 15454 network. If you check the Fully Path Protected option during circuit creation, traffic is protected within the ONS 15454 network. At the destination, another path protection connection is created to bridge traffic from the ONS 15454 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.
10.13 Manual Circuit Routing
Routing circuits manually allows you to:
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CTC imposes the following rules on manual routes:
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Figure 10-11 Alternate Paths for Virtual Path Protection Segments
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Figure 10-12 Mixing 1+1 or BLSR Protected Links With a Path Protection
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Figure 10-13 Ethernet Shared Packet Ring Routing
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Figure 10-14 Ethernet and Path Protection
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If you provision full path protection, 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 10-12 through Table 10-15 summarize the available node connections. Any other combination is invalid and generates an error.
Although virtual path protection segments are possible in VT tunnels, VT tunnels are still considered unprotected. If you need to protect VT circuits use two independent VT tunnels that are diversely routed or use a VT tunnel that is routed over 1+1, BLSR, or a mixture of 1+1 and BLSR links.
10.14 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 CTC calculates for the circuit. If the network is composed 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:
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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:
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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 only used 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.
10.15 Virtual Concatenated Circuits
Virtual concatenated (VCAT) circuits, also called VCAT groups (VCGs), transport traffic using noncontiguous time division multiplexing (TDM) time slots, avoiding the bandwidth fragmentation problem that exists with contiguous concatenated circuits. The cards that support VCAT circuits are the CE-100T-8, FC_MR-4 (both line rate and enhanced mode), and ML-Series cards.
In a VCAT circuit, circuit bandwidth is divided into smaller circuits called VCAT members. The individual members act as independent TDM circuits. All VCAT members should be the same size and must originate/terminate at the same end points. For two-fiber BLSR configurations, some members can be routed on protected time slots and others on PCA time slots.
10.15.1 VCAT Member Routing
The automatic and manual routing selection applies to the entire VCAT circuit, that is, all members are manually or automatically routed. Bidirectional VCAT circuits are symmetric, which means that the same number of members travel in each direction. With automatic routing, you can specify the constraints for individual members; with manual routing, you can select different spans for different members.
Two types of automatic and manual routing are available for VCAT members: common fiber routing and split routing. CE-100T-8, FC_MR-4 (both line rate and enhanced mode), and ML-Series cards support common fiber routing. In common fiber routing, all VCAT members travel on the same fibers, which eliminates delay between members. Three protection options are available for common fiber routing: Fully Protected, PCA, and Unprotected.
CE-100T-8 cards also support split fiber routing, which allows the individual members to be routed on different fibers or each member to have different routing constraints. This mode offers the greatest bandwidth efficiency and also the possibility of differential delay, which is handled by the buffers on the terminating cards. Four protection options are available for split fiber routing: Fully Protected, PCA, Unprotected, and DRI.
In both common fiber and split fiber routing, each member can use a different protection scheme; however, for common fiber routing, CTC checks the combination to make sure a valid route exists. If it does not, the user must modify the protection type. In both common fiber and split fiber routing, intermediate nodes treat the VCAT members as normal circuits that are independently routed and protected by the SONET network. At the terminating nodes, these member circuits are multiplexed into a contiguous stream of data. Figure 10-15 shows an example of common fiber routing.
Figure 10-15 VCAT Common Fiber Routing
Figure 10-16 shows an example of split fiber routing.
Figure 10-16 VCAT Split Fiber Routing
10.15.2 Link Capacity Adjustment
The CE-100T-8 card supports Link Capacity Adjustment Scheme (LCAS), which is a signaling protocol that allows dynamic bandwidth adjustment of VCAT circuits. When a member fails, a brief traffic hit occurs. LCAS temporarily removes the failed member from the VCAT circuit for the duration of the failure, leaving the remaining members to carry the traffic. When the failure clears, the member circuit is automatically added back into the VCAT circuit without affecting traffic. You can select LCAS during VCAT circuit creation.
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Instead of LCAS, the FC_MR-4 (enhanced mode) and ML-Series cards support Software-Link Capacity Adjustment Scheme (SW-LCAS). SW-LCAS is a limited form of LCAS that allows the VCAT circuit to adapt to member failures and keep traffic flowing at a reduced bandwidth. SW-LCAS uses legacy SONET failure indicators like AIS-P and RDI-P to detect member failure. SW-LCAS removes the failed member from the VCAT circuit, leaving the remaining members to carry the traffic. When the failure clears, the member circuit is automatically added back into the VCAT circuit. For ML-Series cards, SW-LCAS allows circuit pairing over two-fiber BLSRs. With circuit pairing, a VCAT circuit is set up between two ML-Series cards; one is a protected circuit (line protection) and the other is PCA. For four-fiber BLSR, member protection cannot be mixed. You select SW-LCAS during VCAT circuit creation. The FC_MR-4 (line rate mode) does not support SW-LCAS.
In addition, you can create non-LCAS VCAT circuits, which do not use LCAS or SW-LCAS. While LCAS and SW-LCAS member cross-connects can be in different service states, all In Group non-LCAS members must have cross-connects in the same service state. A non-LCAS circuit can mix Out of Group and In Group members, as long as the In Group members are in the same service state. Non-LCAS members do not support the OOS-MA,OOG service state; to put a non-LCAS member in the Out of Group VCAT state, use OOS-MA,DSBLD.
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10.15.3 VCAT Circuit Size
Table 10-16 lists supported circuit rates and number of members for each card.
Table 10-16 ONS 15454 Card VCAT Circuit Rates and Members
CE-100T-8
VT1.5
1-64
STS-1
1-31
FC_MR-4 (line rate mode)
STS-1
24 (1 Gbps port)
48 (2 Gbps port)
STS-3c
8 (1 Gbps port)
16 (2 Gbps port)
FC_MR-4 (enhanced mode)
STS-1
1-24 (1 Gbps port)
1-48 (2 Gbps port)
STS-3c
1-8 (1 Gbps port)
1-16 (2 Gbps port)
ML-Series
STS-1, STS-3c, STS-12c
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1 A VCAT circuit with a CE-100T-8 card as a source or destination and an ML-Series card as a source or destination can have only two members.
Use the Members tab on the Edit Circuit window to add or delete members from a VCAT circuit. The capability to add or delete members depends on the card and whether the VCAT circuit is LCAS, SW-LCAS, or non-LCAS.
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Table 10-17 summarizes the VCAT capabilities for each card.
Table 10-17 ONS 15454 VCAT Card Capabilities
CE-100T-8
LCAS
Yes
Yes
Yes
SW-LCAS
No
No
No
Non-LCAS
Yes1
Yes 1
No
FC_MR-4 (enhanced mode)
SW-LCAS
Yes
Yes
Yes
Non-LCAS
No
No
No
FC_MR-4 (line mode)
Non-LCAS
No
No
No
ML-Series
SW-LCAS
No
No
No
Non-LCAS
No
No
No
1 For CE-100T-8 cards, you can add or delete members after creating a VCAT circuit with no protection. During the time it takes to add or delete members (from seconds to minutes), the entire VCAT circuit will be unable to carry traffic.
10.16 Merge Circuits
A circuit merge combines a single selected circuit with one or more circuits. You can merge tunnels, VAP circuits, VLAN-assigned circuits, CTC-created circuits, and TL1-created circuits. To merge circuits, you choose a circuit on the CTC Circuits tab window and the circuits that you want to merge with the chosen (master) circuit on the Merge tab in the Edit Circuits window. The Merge tab shows only the circuits that are available for merging with the master 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.
10.17 Reconfigure Circuits
You can reconfigure multiple circuits, which is typically necessary when a large number of circuits are in the PARTIAL status. When reconfiguring multiple circuits, the selected circuits can be any combination of DISCOVERED, PARTIAL, DISCOVERED_TL1, or PARTIAL_TL1 circuits. You can reconfigure tunnels, VAP circuits, VLAN-assigned circuits, 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
Posted: Tue Nov 27 06:19:37 PST 2007
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