Configuring Channelized OC12/STM4 IQ and IQE Interfaces (SONET Mode)
This section describes how to configure channelized OC12/STM4 intelligent queuing (IQ) and enhanced intelligent queuing (IQE) interfaces, discussing the following topics:
Configuring an OC12/STM4 Interface
You can configure one OC12 interface on a 1-port Channelized OC12/STM4 IQ or IQE PIC. On a 4-port OC12/STM4 IQ or IQE PIC, you can configure one OC12 interface per port. To configure an OC12 interface, include the no-partition and interface-type statements at the [edit interfaces coc12-fpc/pic/port] hierarchy level:
This configuration creates interface so-fpc/pic/port.
![]() | Note: Class-of-service (CoS) rules cannot be applied to an individual channel configured on channelized IQ and IQE interfaces. You can apply CoS rules only to the aggregate bit streams. |
![]() | Note: If you configure the per-unit-scheduler statement on the physical interface of a 4-port Channelized OC-12 IQ PIC and configure 975 logical interfaces or DLCIs, some of the logical interfaces or data link connection identifiers (DLCIs) will drop all packets intermittently. |
Configuring T3 Interfaces
To configure a T3 interface on an OC12 PIC, include the partition, oc-slice, and interface-type statements at the [edit interfaces coc12-fpc/pic/port] hierarchy level, specifying the coc1 interface type:
This configuration creates interface coc1-fpc/pic/port:channel.
Then, include the no-partition interface-type statement at the [edit interfaces coc1-fpc/pic/port:channel] hierarchy level, specifying the t3 interface type:
This configuration creates interface t3-fpc/pic/port:channel.
The partition number is the sublevel interface partition index and is correlated with the channel number. For channelized OC1 interfaces, the partition number can be from 1 through 12.
![]() | Note: For channelized OC12 interfaces, channel numbering begins with 0 (:0). For channelized OC12/STM4 IQ and IQE interfaces, channel numbering begins with 1 (:1). |
The OC-slice range is the range of SONET/SDH slices. For SONET/SDH interfaces, the OC-slice range specifies the bandwidth size required for the interface type you are configuring. For channelized OC1 interfaces, the OC slice can be from 1 through 12. You can configure only one OC slice per channelized OC1 interface.
The interface type is the channelized interface type or clear channel you are creating. For channelized OC12 interfaces, type can be so or coc1.
![]() | Note: Channelized OC12/STM4 IQ and IQE interfaces in M Series, MX Series, and T Series routers reserve channels 0 through 3 of each OC12 space for STS3c SONET channels. When you configure E3 or T3 channels in OC12 spaces on the described PICs, Junos OS allocates them starting from channel 4 because channels 0 through 3 are reserved for four STS3c SONET channels. Channel numbers are allocated sequentially in the following order: 4, 5, 6, 7, 8, 9, 11, 0, 1, 2, 3. Only after channels 4 through 11 of the OC12 space are exhausted (that is, channels 4 through 11 are configured) for E3 or T3 channels will Junos OS then allocate the channel 0–3 space for further E3 or T3 channels; thereby using up the 0–3 space previously reserved for four STS3c SONET channels. If a subsequent reconfiguration of this OC12 space occurs, where you try to replace channels 4–6 or 7–9 with an OC3 SONET channel; it fails because the channel 0–3 space is already occupied by the last E3 or T3 channels configured. This causes a failure in channel allocation and the device control daemon (dcd) keeps retrying forever to configure the channel allocation on the interface. The only resolution is to reconfigure the last configured E3 or T3 channels with OC3 channels, to free channels 0 through 3. |
Example: Configuring T3 Interfaces
Configure a T3 interface using partition 3 and OC slice 3. This configuration creates interface t3-1/1/0:3:
For a full configuration example, see the Junos OS Feature Guides.
Configuring OC3 Interfaces
To configure an OC3 interface, include the partition, oc-slice, and interface-type statements at the [edit interfaces coc12-fpc/pic/port] hierarchy level, specifying the so interface type:
The partition number is the sublevel interface partition index. For SONET/SDH interfaces, the partition number does not correlate with bandwidth size. For OC3 interfaces, the partition number can be from 1 through 4.
![]() | Note: For channelized OC12 interfaces, channel numbering begins with 0 (:0). For channelized OC12 IQ and IQE interfaces, channel numbering begins with 1 (:1). |
The OC-slice range is the range of SONET/SDH slices. For SONET/SDH interfaces, the OC-slice range specifies the bandwidth size required for the interface type you are configuring. OC3 interfaces must occupy three consecutive OC slices per interface, in one of the following forms:
- 1–3
- 4–6
- 7–9
- 10–12
By contrast, the T3 and OC1 IQ interfaces each occupy one OC slice per interface.
The interface type is the channelized interface type or data channel you are creating. For channelized OC12 interfaces, the interface type can be coc1 or so.
Example: Configuring OC3 Interfaces
Configure an OC3 interface, using partition 1 and OC slices 4 through 6. This configuration creates interface so-1/1/0:1:
For a full configuration example, see the Junos OS Feature Guides.
Configuring T1 Interfaces on Channelized OC12 IQ and IQE Interfaces
To configure T1 interfaces on a Channelized OC12 IQ or IQE PIC, perform the following tasks:
- Partition the channelized OC12 interface into channelized
OC1 interfaces by including the partition, oc-slice, and interface-type statements at the [edit interfaces coc12-fpc/pic/port] hierarchy level, specifying the coc1 interface type:[edit interfaces coc12-fpc/pic/port]partition partition-number oc-slice oc-slice-range interface-type (Interfaces) coc1;
- If your network equipment uses virtual tributary (VT)
mapping, partition the channelized OC1 interface into T1 interfaces
by including the partition and interface-type statements
at the [edit interfaces coc1-fpc/pic/port] hierarchy level, specifying
the t1 interface type:[edit interfaces coc1-fpc/pic/port]partition partition-number interface-type (Interfaces) t1;
- If your network equipment uses M13 or C-bit parity, convert
the channelized OC1 interface into a channelized T3 interface by including
the no-partition and interface-type statements
at the [edit interfaces coc1- fpc/pic/port:channel] hierarchy level, specifying the ct3 interface type.
Note that because the no-partition statement is included,
this configuration does not create another level of channelization,
as denoted by the number of colons in the resulting interface.[edit interfaces coc1-fpc/pic/port]no-partition partition-number interface-type (Interfaces) ct3;
- Partition the channelized T3 interface into T1 interfaces
by including the partition and interface-type statements
at the [edit interfaces ct3-fpc/pic/port] hierarchy level,
specifying the t1 interface type:[edit interfaces ct3-fpc/pic/port]partition partition-number interface-type (Interfaces) t1;
Note: Class-of-service (CoS) rules cannot be applied to an individual channel configured on channelized IQ interfaces. You can apply CoS rules only to the aggregate bit streams.
Figure 1 shows VT-mapped and M13 or C-bit parity-mapped configurations of T1 interfaces.
Figure 1: T1 Interfaces on a Channelized OC12 PIC

Example: Configuring T1 Interfaces
Configure the following T1 interfaces:
VT-Mapped Configuration
M13 or C-bit Parity-Mapped Configuration
For a full configuration example, see the Junos OS Feature Guides.
Configuring NxDS0 Interfaces
To configure NxDS0 interfaces on a Channelized OC12 IQE PIC, perform the following tasks:
- Partition the channelized OC12 IQE interface into channelized
OC1 interfaces by including the partition, oc-slice, and interface-type statements at the [edit interfaces coc12-fpc/pic/port] hierarchy level, specifying the coc1 interface type:[edit interfaces coc12-fpc/pic/port]partition partition-number oc-slice oc-slice-range interface-type (Interfaces) coc1;
- If your network equipment uses VT mapping, partition the
channelized OC1 interface into channelized T1 interfaces by including
the partition and interface-type statements at
the [edit interfaces coc1-fpc/pic/port] hierarchy level,
specifying the ct1 interface type:[edit interfaces coc1-fpc/pic/port]partition partition-number interface-type (Interfaces) ct1;
Note: Class-of-service (CoS) rules cannot be applied to an individual channel configured on channelized IQ interfaces. You can apply CoS rules only to the aggregate bit streams.
- If your network equipment uses M13 or C-bit parity, convert
the channelized OC1 interface into a channelized T3 interface by including
the no-partition and interface-type statements
at the [edit interfaces coc1-fpc/pic/port] hierarchy level, specifying
the ct3 interface type:[edit interfaces coc1-fpc/pic/port]no-partition partition-number interface-type (Interfaces) ct3;
Note: Because the no-partition statement is included, this configuration task does not create another level of channelization, as denoted by the number of colons in the resulting interface.
- Partition the channelized T3 interface into channelized
T1 interfaces by including the partition and interface-type statements at the [edit interfaces ct3-fpc/pic/port] hierarchy
level, specifying the ct1 interface type:[edit interfaces ct3-fpc/pic/port]partition partition-number interface-type (Interfaces) ct1;
- Configure channelized NxDS0 IQ interfaces
on the channelized T1 IQ interface by including the partition, timeslots, and interface-type statements at
the [edit interfaces ct1-fpc/pic/port] hierarchy level, specifying
the ds interface type:[edit interfaces ct1-fpc/pic/port:channel:channel]partition partition-number timeslots time-slot-range interface-type (Interfaces) ds;
Figure 2 shows VT-mapped and M13 or C-bit parity-mapped configurations of NxDS0 IQ interfaces.
Figure 2: Sample Channelization of OC12 IQE PIC

Example: Configuring NxDS0 Interfaces
Configure the following two NxDS0 interfaces with 10 time slots and 4 time slots, respectively:
VT-Mapped Configuration
M13 or C-bit Parity-Mapped Configuration
For a full configuration example, see the Junos OS Feature Guides.
Configuring Fractional T1 Interfaces
By default, all the time slots on a channelized T1 interface are used. To configure a fractional T1 interface on a Channelized OC12 IQE PIC, perform the following tasks:
- Configure a T1 interface. For more information, see Configuring T1 Interfaces.
- Configure the number of time slots allocated to the T1
interface by including the timeslots statement at the [edit interfaces t1-fpc/pic/port<:channel> t1-options] hierarchy level:[edit interfaces t1-fpc/pic/port<:channel> t1-options]timeslots time-slot-range;
For channelized T1 interfaces, the time-slot range is from 1 through 24. You can designate any combination of time slots. To configure ranges, use hyphens. To configure discontinuous time slots, use commas. Do not include spaces. For more information, see Configuring Fractional T1 Time Slots.
Example: Configuring Fractional T1 Interfaces
Configure a fractional T1 interface that uses time slots 1 through 5 and 10:
For a full configuration example, see the Junos OS Feature Guides.