-
- Downstream Interface Configuration
- Upstream Interface Configuration
- DOCSIS Interface and Fiber Node Configuration
- DOCSIS Load Balancing Groups
- DOCSIS Load Balancing Movements
- DOCSIS 3.0 Downstream Bonding
- DOCSIS 2.0 A-TDMA Modulation Profiles
- Downstream Resiliency Bonding Group
- Downstream Channel ID Assignment
- Upstream Channel Bonding
- Spectrum Management and Advanced Spectrum Management
- Upstream Scheduler Mode
- Generic Routing Encapsulation
- Transparent LAN Service over Cable
- Downgrading Channel Bonding in Battery Backup Mode
- Energy Management Mode
- Upstream Bonding Support for D-PON
-
- IP Access Control Lists
- Creating an IP Access List and Applying It to an Interface
- Creating an IP Access List to Filter IP Options, TCP Flags, Noncontiguous Ports
- Refining an IP Access List
- IP Named Access Control Lists
- IPv4 ACL Chaining Support
- IPv6 ACL Chaining with a Common ACL
- Commented IP Access List Entries
- Standard IP Access List Logging
- IP Access List Entry Sequence Numbering
- ACL IP Options Selective Drop
- ACL Syslog Correlation
- IPv6 Access Control Lists
- IPv6 Template ACL
- IPv6 ACL Extensions for Hop by Hop Filtering
-
- Call Home
- SNMP Support over VPNs—Context-Based Access Control
- SNMP Cache Engine Enhancement
- Onboard Failure Logging
- Control Point Discovery
- IPDR Streaming Protocol
- Usage-Based Billing (SAMIS)
- Frequency Allocation Information for the Cisco CMTS Routers
- Flap List Troubleshooting
- Maximum CPE and Host Parameters
- SNMP Background Synchronization
- Online Offline Diagnostics
- Index
Downstream Channel
ID Assignment
First Published: April 17, 2015
The DOCSIS downstream channel ID (DCID) is defined as an 8-bit identifier for recognizing a Downstream Channel within a MAC Domain. All CMTS downstream channels are assigned a DCID by default that may be subsequently changed by configuration. It is used in most DOCSIS downstream packet headers and its valid range is from 1 to 255 (0 is reserved for network management purposes).
Note | All downstream channels in a MAC domain must have a unique DCID within the MAC domain. |
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://tools.cisco.com/ITDIT/CFN/. An account on http://www.cisco.com/ is not required.
Contents
- Hardware Compatibility Matrix for Cisco cBR Series Routers
- Information About Downstream Channel ID Assignment on the Cisco CMTS Routers
- How to Configure Downstream Channel ID Assignment on the Cisco CMTS Routers
- Additional References
- Feature Information for DS Channel ID Assignment
Hardware Compatibility Matrix for Cisco cBR Series Routers
Note | The hardware components introduced in a given Cisco IOS-XE Release are supported in all subsequent releases unless otherwise specified. |
Cisco CMTS Platform |
Processor Engine |
Interface Cards |
---|---|---|
Cisco cBR-8 Converged Broadband Router |
Cisco IOS-XE Release 3.15.0S and Later Releases Cisco cBR-8 Supervisor:
|
Cisco IOS-XE Release 3.15.0S and Later Releases Cisco cBR-8 CCAP Line Cards: Cisco cBR-8 Downstream PHY Modules: Cisco cBR-8 Upstream PHY Modules: |
Information About Downstream Channel ID Assignment on the Cisco CMTS Routers
These are the downstream channel ID assignment features:
-
Unique DCIDs are provided for all channels within a single controller by default.
Note
DCID values for downstream channels in the same MAC Domain must be unique. If a MAC Domain only contains channels from a single controller, the default DCID values will be sufficient. If a MAC Domain contains channels from multiple controllers, DCID conflicts may be encountered within the MAC Domain. DCID conflicts may be resolved by changing the DCID value of the conflicting channels within the controller configuration or by enabling the automatic channel ID assignment feature.
-
The default DCID value for each downstream channel within a controller is equivalent to rf-chan number plus one. For example, the default value for rf-chan 0 is 1, for rf-chan 1 is 2.
- Manual Downstream Channel ID Assignment
- Automatic Downstream Channel ID Assignment on the Cisco CMTS Routers
Manual Downstream Channel ID Assignment
|
0/0 |
1/0 |
2/0 |
3/0 |
6/0 |
7/0 |
8/0 |
9/0 |
---|---|---|---|---|---|---|---|---|
DS Controller 0 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
DS Controller 1 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
DS Controller 2 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
DS Controller 3 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
DS Controller 4 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
DS Controller 5 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
DS Controller 6 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
DS Controller 7 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
1-128 |
Router#show controllers integrated-Cable 3/0/0 rf-channel 1-127 Chan State Admin Frequency Type Annex Mod srate Interleaver dcid power output 1 NPRE UP 99000000 DOCSIS B 256 5361 I32-J4 2 37 NORMAL 2 NPRE UP 105000000 DOCSIS B 256 5361 I32-J4 3 37 NORMAL 3 NPRE UP 111000000 DOCSIS B 256 5361 I32-J4 4 37 NORMAL 4 NPRE UP 117000000 DOCSIS B 256 5361 I32-J4 5 37 NORMAL 5 NPRE UP 123000000 DOCSIS B 256 5361 I32-J4 6 37 NORMAL 6 NPRE UP 129000000 DOCSIS B 256 5361 I32-J4 7 37 NORMAL 7 NPRE UP 135000000 DOCSIS B 256 5361 I32-J4 8 37 NORMAL 8 NPRE UP 141000000 DOCSIS B 256 5361 I32-J4 9 37 NORMAL 9 NPRE UP 147000000 DOCSIS B 256 5361 I32-J4 10 37 NORMAL 10 NPRE UP 153000000 DOCSIS B 256 5361 I32-J4 11 37 NORMAL 11 NPRE UP 159000000 DOCSIS B 256 5361 I32-J4 12 37 NORMAL 12 NPRE UP 165000000 DOCSIS B 256 5361 I32-J4 13 37 NORMAL 13 NPRE UP 171000000 DOCSIS B 256 5361 I32-J4 14 37 NORMAL 14 NPRE UP 177000000 DOCSIS B 256 5361 I32-J4 15 37 NORMAL 15 NPRE UP 183000000 DOCSIS B 256 5361 I32-J4 16 37 NORMAL Router#
Automatic Downstream Channel ID Assignment on the Cisco CMTS Routers
It is possible to automatically assign a unique set of downstream channel IDs to meet all DOCSIS requirements by enabling the Automatic DCID Assignment feature. When enabled, Downstream channel DCIDs will be automatically assigned when the channels are added to a fiber node and associated with a MAC Domain. Therefore, the use of fiber node configuration is a prerequisite for this feature.
Service Impact
Changing the DOCSIS downstream channel ID causes cable modems to re-register. Cable modems receive MAC Domain Descriptor (MDD) and Upstream Channel Descriptor (UCD) messages with a changed DCID in their headers.
-
Enabling the automatic DCID assignment displays the following message:
WARNING: Enabling automatic DCID assignment will cause modems to flap and will apply to all fiber nodes on this CMTS.
-
Disabling the automatic DCID assignment displays the following message:
WARNING: Disabling automatic DCID assignment will no longer enforce channel-id uniqueness at fiber nodes. Channel ID changes may require manual verification to prevent conflicts.
-
If there is a DCID conflict with another channel in the MAC Domain, the following error message is displayed:
ERROR: <slot>/<subslot>/<controller> rf-channel <channel>: The downstream channel id conflicts with interface In<slot>/<subslot>/<controller>:channel. Downstream channel id must be unique in a CGD.
-
After automatic DCID assignment is configured, if there is a DCID conflict when a downstream channel that belongs to a fiber node is added to a MAC Domain, the automatic DCID feature tries to resolve the conflict by assigning another automatic DCID and the following message is displayed:
WARNING: The downstream channel id conflict for <slot>/<subslot>/<controller> rf-channel <channel> was resolved by Automatic DCID Assignment. Please run "interface <md-slot>/<md-subslot>/<md-index>" followed by "<slot>/<subslot>/<controller> rf-channel <channel>" again in order to add the channel.
To add the channel, use this channel grouping domain (CGD) command again:
cable downstream x/y/z rf-channel channel
-
If automatic DCID is configured and the channel does not belong to a fiber node, or if automatic DCID cannot resolve the conflict, the following message is displayed:
WARNING: The downstream channel id conflict for <slot>/<subslot>/<controller> rf-channel <channel> could not be resolved by Automatic DCID Assignment.
To resolve this issue, add the channel to a fiber node.
How to Configure Downstream Channel ID Assignment on the Cisco CMTS Routers
The following sections describe how to configure downstream channel ID assignment.
- Configuring Manual Downstream Channel ID Assignment
- Configuring Automatic Downstream Channel ID Assignment
Configuring Manual Downstream Channel ID Assignment
Configuring Automatic Downstream Channel ID Assignment
Automatic DCID assignment should be permanently configured. However, if you need to remove the feature, use the no or default commands.
Note | The no or default form of the command is not written to startup-config file. |
In this case, the DCIDs are retained as computed for all channels, and are not set to the defaults of the channels. Save the configuration containing the newly-assigned DCIDs to the startup-config file by using the write memory command.
When you enable automatic DCID assignment, any DCID conflict arising due to adding a channel to a MAC Domain is resolved automatically.
-
After running the cable downstream-channel-id automatic command in the configuration, manually editing the configuration file in an editor to add RF channels to the fiber nodes could cause DCID conflicts. The feature assumes all channels in fiber nodes have unique automatic DCIDs in global configuration mode. If the configuration is manually edited and the feature does not verify the unique DCIDs, the DCIDs of the newly-added channels may conflict with those of the existing channels. To fix any DCID conflicts, undo and re-apply the global automatic DCID configuration.
Note
Re-applying global automatic DCID configuration is a disruptive operation.
To avoid DCID conflicts, edit the configuration to configure the fiber nodes, then run the cable downstream-channel-id automatic command so all channels have unique automatic DCIDs.
Make additions to the fiber nodes on the Cisco uBR10012 router command line interface with the automatic DCID configured.
- The cable downstream-channel-id automatic command should not be manually edited in to the startup-config file, since it does not guarantee unique DCIDs for channels in the fiber node.
Example
This example displays the restriction on manually editing configurations:
Router# show run | include automatic cable downstream-channel-id automatic router# show cable fiber-node 3 --------------------------------------------------------------------------------- Fiber-Node 3 Channel(s) : downstream Integrated-Cable 1/0/2: 0-3, 32-35, 64-67, 96-99 Channel ID(s): 1 2 3 4 33 34 35 36 65 66 67 68 97 98 99 100 Upstream-Cable 1/0/2 FN Config Status: Configured (status flags = 0x01) MDD Status: Valid Router#
If you manually edit the startup-config file in an editor to add a downstream controller, for example, 1/0/3, it causes a conflict.
Router> configure terminal Router# cable fiber-node 3 Router# downstream integrated-Cable 1/0/3
If this downstream controller is added, the automatic DCID assignment feature automatically resolves it. However, since the startup-config file was manually edited to add the downstream controller, the automatic DCID assignment feature is unable to resolve it. This causes a DCID conflict when the edited startup-config file is loaded and invalidates the fiber node.
down Modular-Cable 5/0/0 rf-channel 0 DS frequency is not unique. DS channel id is not unique. Warning: D3.0 CMs cannot get w-online with an invalid fiber-node. router#
Run the show cable fibernode command to view DCIDs assigned to all the channels in the fiber node.
Router# show cable fiber-node 3 Fiber-Node 3 Channel(s) : downstream Integrated-Cable 1/0/2: 0-3, 32-35, 64-67, 96-99 Channel ID(s): 1 2 3 4 33 34 35 36 65 66 67 68 97 98 99 100 Upstream-Cable 1/0/2 FN Config Status: Configured (status flags = 0x01) MDD Status: Valid
Additional References
Technical Assistance
Description |
Link |
---|---|
The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies. To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds. Access to most tools on the Cisco Support website requires a Cisco.com user ID and password. |
Feature Information for DS Channel ID Assignment
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://tools.cisco.com/ITDIT/CFN/. An account on http://www.cisco.com/ is not required.
Note | The below table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature. |
Feature Name |
Releases |
Feature Information |
---|---|---|
Downstream Channel ID Assignment |
Cisco IOS-XE 3.15.0S |
This feature was introduced on the Cisco cBR Series Converged Broadband Router. |