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Fabric Plane Management

Configuring Fabric Redundancy Mode for Active Control Boards on MX Series Routers

An MX960 router can support three Enhanced Switch Control Boards (SCBE2s or SCBEs)—two planes on each SCB and make up a total of six fabric planes. MX240 and MX480 routers can support up to two SCBE2s or SCBEs—four fabric planes on each SCBE make up a total of eight planes. However, the MX240 and MX480 routers have only six active planes. The remaining two are redundant. MX2020 routers can support eight Switch Fabric Boards (SFBs) or 24 fabric planes.

Note:

The MPC7E-MRATE and MPC7E-10G MPCs are supported only on MX-SCBE2.

You can configure the active control board to be in redundancy mode or in increased fabric bandwidth mode. You can enable increased fabric bandwidth of active control boards for optimal and efficient performance and traffic handling by configuring the active control boards to be in redundancy mode. To configure redundancy mode for the active control board, use the redundancy-mode redundant statement at the [edit chassis fabric] hierarchy level:

When you configure this option, all the FPCs use 4 fabric planes as active planes, regardless of the type of the FPC.

To configure increased bandwidth mode for the active control board, use the redundancy-mode increased-bandwidth statement at the [edit chassis fabric] hierarchy level:

In increased fabric bandwidth mode, MX Series routers will use 6 active planes. MX240 and MX480 routers will also use 2 spare planes in addition to the 6 active planes.

Increased fabric bandwidth mode is enabled by default on MX routers with Switch Control Board (SCB). On MX routers with Enhanced SCB—SCBE, regardless of the type of MPC or DPC installed on it, redundancy mode is enabled by default.

Configuring this feature does not affect the system. You can configure this feature without restarting the FPC or restarting the system.

See also: MX-Series Switch Control Board (SCB) Description

Example: Configuring Fabric Redundancy Mode

Requirements for Configuration of the Fabric Redundancy Mode

This example uses the following hardware and software components:

  • Junos OS Release 12.3 R2 or later for MX Series routers

  • A single MX480 router with MPC4E

Overview

This example provides information about configuring the fabric redundancy mode on an MX480 router with MPC4E. You can configure the MPC4E to function in redundant fabric mode or increased bandwidth mode. If you do not configure the mode, the MPC4E, by default, functions in redundant fabric mode. In redundant fabric mode, the number of active fabric planes is 4. If you configure the MPC4E to function in increased bandwidth mode, the number of active fabric planes increases to 6.

See also: 32x10GE MPC4E and 2x100GE + 8x10GE MPC4E.

Configuring Increased Bandwidth Mode

Procedure

Step-by-Step Procedure

In this example, you configure increased bandwidth mode on an MX480 router with MPC4E. The existing fabric mode on the MX480 router is redundant fabric mode. To configure the fabric mode, perform the following tasks:

  1. Verify the existing fabric mode of the router by using the show chassis fabric mode command.

  2. View the number of active fabric planes by using the show chassis fabric summary command.

    Type 4 and Type 5 MPCs refer to MPC 4 and MPC5 line cards, respectively.

  3. In configuration mode, go to the [edit chassis] hierarchy level and set the fabric mode to increased-bandwidth as follows:

Results

In redundant fabric mode, the number of active fabric planes is 4 while the number of spare planes is also 4. In increased-bandwidth mode, the number of active planes is 6 while the number of spare planes is 2.

Note:

Fabric planes 1 and 5 and fabric planes 3 and 7 use shared physical links. So, among fabric planes 1 and 5, only one plane can be active. Similarly, among fabric planes 3 and 7, only one plane can be active.

Verification

To verify that the fabric mode of the MX480 router with MPC4E, perform the following tasks:

Verifying the Fabric Redundancy Mode of the Router

Purpose

To verify that the fabric redundancy mode of the MX480 router with MPC4E has been modified to increased-bandwidth.

Action

To view the fabric mode of the router, use the show chassis fabric mode command.

Meaning

The MX480 router with MPC4E is functioning in increased bandwidth mode.

Verifying the Number of Active Fabric Planes

Purpose

To verify that the number of active fabric planes is 6.

Action

To view the number of active fabric planes, use the show chassis fabric summary command.

Type 4 and Type 5 MPCs refer to MPC 4 and MPC5 line cards, respectively.

Meaning

Number of active planes on the MX480 router with MPC4E is 6 (0, 1, 2, 3, 4, and 6) while the number of spare planes is 2.

Fabric Plane Management on AS MLC Modular Carrier Card

The Application Services Modular Line Card (AS MLC) provides high application throughput and storage space, and is designed to run services on the MX240, MX480, and MX960 routers. The AS MLC consists of the following components:

  • Application Services Modular Carrier Card (AS MCC)

  • Application Services Modular Processing Card (AS MXC)

  • Application Services Modular Storage Card (AS MSC)

The AS MCC plugs into the chassis and provides the fabric interface.

An MX960 router can support three Switch Control Boards (SCBs) or six fabric planes. The AS MCC supports six fabric planes. An MX240 or MX480 router can support upto two SCBs or two fabric planes. The AS MCC at any time can provide connectivity to only six of the eight fabric planes. Fabric planes 1 and 5, and 3 and 7 use shared physical links. So between fabric planes 1 and 5 only one plane can be active. Similarly between fabric planes 3 and 7, only one plane can be active.

This behavior impacts the output of fabric-related monitoring commands on MX240 and MX480 routers with AS MCCs.

The show chassis fpc pic-status command displays the output for an MX480 router with an AS MCC:

In the show chassis fpc pic-status command output, Slot 1 and 5 are AS MCC, PIC 0 is the AS MSC, and PIC 2 is the AS MXC.

The show chassis fabric fpcs command displays the output on an MX480 router with an AS MCC.

In the show chassis fabric fpcs command output, FPC 5 is the AS MCC.

The show chassis fabric plane command displays the output on an MX480 router with an AS MCC.

In the show chassis fabric plane output, FPC 5 is the AS MCC.

The term Unused in the output for the show chassis fabric fpcs and show chassis fabric plane command indicates that one fabric plane from each pair that share physical links (1 and 5, and 3 and 7) is inactive.

See Junos OS System Basics and Services Command Reference for more information.

Fabric Plane Management on JNP10K-LC2101

JNP10K-LC2101 is a fixed-configuration MPC that provides increased port density and performance to MX10008 routers. JNP10K-LC2101 plugs into the chassis and provides the fabric interface.

An MX10008 router has six Switch Fabric Boards (SFBs). JNP10K-LC2101 has six Packet Forwarding Engines, each having 24 connections to the fabric (24 planes, or 4 connections per SFB). MX10008 routers with JNP10K-LC2101 will have 24 planes active when all the six SFBs are populated. However, in case of a failure of one SFB, the line rate can be achieved with 20 planes. The fabric supports a link speed of 25 Gbps.

The MX10008 SFB also supports fabric hardening. Fabric hardening is the process of controlling bandwidth degradation to prevent null route. The following key CLI commands are available for fabric hardening:

  • set chassis fpc slot-number fabric bandwidth-degradation percentage—Configures the FPC to take a specific action once bandwidth degradation reaches a certain percentage to avoid causing a null route in the chassis.

  • set chassis fabric degraded detection-enable—Enables detection of an FPC with degraded fabric.

  • set chassis fabric degraded action-fpc-restart-disable—Disables line card restarts to limit recovery actions from a degraded fabric condition.

In MX10008 SFBs, fabric fault handling is supported per plane. Fabric fault handling per plane results in increased granularity, which helps identify, isolate, and repair faults. If an SFB has a single faulty plane, the other three planes can continue to operate. There is no need to take the entire SFB offline. For example, if a plane encounters a training failure error, the line card isolates that faulty plane; while the other planes continue to operate. Also, any cyclic redundancy check (CRC) errors on any link on the SFB are indicated on the plane, not on SFB.

Signaling Neighboring Routers of Fabric Down on T640 and T1600 Routers

In JUNOS OS Release 10.4 and later, T640 and T1600 routers signal neighboring routers if they are unable to carry traffic due to all fabric planes being taken offline for one of the following reasons:

  • CLI or button press initiated offline state.

  • Automatically taken offline by the SPMB due to high temperature.

  • PIO errors or voltage errors detected by the SPMB CPU to the SIBs.

The following scenarios are not supported:

  • All PFEs get destination errors on all planes to all destinations, even with the Switch Interface Boards (SIBs) staying online.

  • Complete fabric loss caused by destination timeouts, with the SIBs still online.

When chassisd detects all fabric planes are down, the router reboots all the FPCs in the system. When the FPCs come back up, the interfaces will not be created again, since all the fabric planes are down.

Once the user diagnoses and fixes the cause of all fabric planes going down, the user must then online the SIBs. The SIB online process brings up the interfaces.

Fabric down signaling to neighboring routers offers the following benefits:

  • FPCs reboot when the control plane connection to the RE times out.

  • Extends a simple approach to reboot FPCs when the dataplane blacks out.

When the router transitions from a state where SIBs are online or spare to a state where there are no SIBs in online state, then all the FPCs in the system are rebooted.

An ERRMSG indicates if all fabric planes are down and the FPCs will be rebooted if any fabric planes do not come up in 2 minutes.

An ERRMSG indicates the reason for FPC reboot on fabric connectivity loss.

The chassisd daemon traces when an FPC comes online, but PIC attach is not done due to no fabric plane present.

A warning is issued in the CLI when the last fabric plane is taken offline, that FPCs will reboot. You will need to online the SIBs after fixing the cause of the SIBs not being online. When the first SIB goes online, and link training with the FPCs completes, the interfaces will be created.

Fabric down signaling to neighboring routers functionality is available by default, and no user configuration required to enable it.

No CLI commands or alarms are required for this feature. Alarms indicate an SIBs offline system state to the user.