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Monitoring Fast Ethernet and Gigabit Ethernet Interfaces

 

Checklist for Monitoring Fast Ethernet and Gigabit Ethernet Interfaces

Purpose

To monitor Fast Ethernet and Gigabit Ethernet interfaces and begin the process of isolating interface problems when they occur.

Action

Table 1 provides links and commands for monitoring Fast Ethernet and Gigabit Ethernet interfaces.

Table 1: Checklist for Monitoring Fast Ethernet and Gigabit Ethernet Interfaces

Tasks

Command or Action

Monitor Fast Ethernet and Gigabit Ethernet Interfaces
  1. Display the Status of Fast Ethernet Interfaces

show interfaces terse (fe* | ge*)

  1. Display the Status of a Specific Fast Ethernet or Gigabit Ethernet Interface

show interfaces (fe-fpc/pic/port | ge-fpc/pic/port)

  1. Display Extensive Status Information for a Specific Fast Ethernet or Gigabit Ethernet Interface

show interfaces (fe-fpc/pic/port | ge-fpc/pic/port) extensive

  1. Monitor Statistics for a Fast Ethernet or Gigabit Ethernet Interface

monitor interface (fe-fpc/pic/port | ge-fpc/pic/port)

  1. Fiber-Optic Ethernet Interface Specifications

 

Meaning

You can use the above described commands to monitor and to display the configurations for Fast Ethernet and Gigabit Ethernet interfaces.

Monitor Fast Ethernet and Gigabit Ethernet Interfaces

By monitoring Fast Ethernet and Gigabit Ethernet interfaces, you begin to isolate Fast Ethernet and Gigabit Ethernet interface problems when they occur.

To monitor your Fast Ethernet and Gigabit Ethernet interfaces, follow these steps:

  1. Display the Status of Fast Ethernet Interfaces

  2. Display the Status of Gigabit Ethernet Interfaces

  3. Display the Status of a Specific Fast Ethernet or Gigabit Ethernet Interface

  4. Display Extensive Status Information for a Specific Fast Ethernet or Gigabit Ethernet Interface

  5. Monitor Statistics for a Fast Ethernet or Gigabit Ethernet Interface



Display the Status of Fast Ethernet Interfaces

Purpose

To display the status of Fast Ethernet interfaces, use the following Junos OS command-line interface (CLI) operational mode command:

Action

Sample Output

user@host> show interfaces terse fe*

Meaning

The sample output lists only the Fast Ethernet interfaces. It shows the status of both the physical and logical interfaces. For a description of what the output means, see Table 2.

Table 2: Status of Fast Ethernet Interfaces

Physical Interface

Logical Interface

Status Description

fe-2/1/0

Admin Up

Link Up

fe-2/1/0.0

Admin Up

Link Up

This interface has both the physical and logical links up and running.

fe-3/0/2

Admin Up

Link Down

fe-3/0/2.0

Admin Up

Link Down

This interface has the physical link down, the link layer down, or both down (Link Down). The logical link is also down as a result.

fe-4/1/0

Admin Down

Link Up

fe-4/1/0.0

Admin Up

Link Down

This interface is administratively disabled and the physical link is healthy (Link Up), but the logical interface is not established. The logical interface is down because the physical link is disabled.

fe-4/1/2

Admin Up

Link Down

fe-4/1/2.0

Admin Up

Link Down

This interface has both the physical and logical links down.



Display the Status of Gigabit Ethernet Interfaces

Purpose

To display the status of Gigabit Ethernet interfaces, use the following Junos OS command-line interface (CLI) operational mode command:

Action

Sample Output

user@host> show interfaces terse ge*

Meaning

This sample output lists only the Gigabit Ethernet interfaces. It shows the status of both the physical and logical interfaces. See Table 3 for a description of what the output means.

Table 3: Status of Gigabit Ethernet Interfaces

Physical Interface

Logical Interface

Status Description

ge-2/2/0

Admin Down

Link Down

ge-2/2/0.0

Admin Up

Link Down

This interface is administratively disabled (Admin Down). Both the physical and logical links are down (Link Down).

ge-2/3/0

Admin Up

Link Up

ge-2/3/0.0

Admin Up

Link Up

This interface has both the physical and logical links up and running.

ge-3/2/0

Admin Up

Link Down

ge-3/2/0.0

Admin Up

Link Down

This interface has both the physical link and the logical interface down.



Display the Status of a Specific Fast Ethernet or Gigabit Ethernet Interface

Purpose

To display the status of a specific Fast Ethernet or Gigabit Ethernet interface when you need to investigate its status further, use the following Junos OS CLI operational mode command:

Action

Sample Output 1

The following sample output is for a Fast Ethernet interface with the physical link up:

Sample Output 2

The following output is for a Gigabit Ethernet interface with the physical link up:

Meaning

The first line of sample output 1 and 2 shows that the physical link is up. This means that the physical link is healthy and can pass packets. Further down the sample output, look for active alarms and defects. If you see active alarms or defects, to further diagnose the problem, see Step 3, Display Extensive Status Information for a Specific Fast Ethernet or Gigabit Ethernet Interface, to display more extensive information about the Fast Ethernet interface and the physical interface that is down.



Display Extensive Status Information for a Specific Fast Ethernet or Gigabit Ethernet Interface

Purpose

To display extensive status information about a specific Fast Ethernet or Gigabit Ethernet interface, use the following Junos OS CLI operational mode command:

Action

Sample Output

The following sample output is for a Fast Ethernet interface:

Meaning

The sample output shows where the errors might be occurring and includes autonegotiation information. See Table 4 for a description of errors to look for.

Table 4: Errors to Look For

Error

Meaning

Policed discards

Discarded frames that were not recognized or were not of interest.

L2 channel errors

Packets for which the router could not find a valid logical interface. For example, the packet is for a virtual LAN (VLAN) that is not configured on the interface.

MTU

The maximum transmission unit (MTU) must match the interface of either the router at the remote end of the Fast Ethernet or Gigabit Ethernet link, or that of the switch.

Input DA rejects

Number of packets with a destination Media Access Control (MAC) address that is not on the accept list. It is normal to see this number increment.

Input SA rejects

Number of packets with a source MAC address that is not on the accept list. This number only increments when source MAC address filtering is configured.

If the physical link is down, look at the active alarms and defects for the Fast Ethernet or Gigabit Ethernet interface and diagnose the Fast Ethernet or Gigabit Ethernet media accordingly. See Checklist for Locating Fast Ethernet and Gigabit Ethernet Alarms and Counters for an explanation of Fast Ethernet and Gigabit Ethernet alarms.

Table 5 lists and describes some MAC statistics errors to look for.

Table 5: MAC Statistics Errors

Error

Meaning

CRC/Align errors

The total number of packets received that had a length (excluding framing bits, but including FCS octets) of between 64 and 1518 octets, inclusive, but had either a bad FCS with an integral number of octets (FCS Error) or a bad FCS with a non-integral number of octets (Alignment Error).

MAC control frames

The number of MAC control frames.

MAC pause frames

The number of MAC control frames with pause operational code.

Jabber frames

The total number of packets received that were longer than 1518 octets (excluding framing bits, but including FCS octets), and had either an FCS error or an alignment error.

Note that this definition of jabber is different from the definition in IEEE-802.3 section 8.2.1.5 (10BASE5) and section 10.3.1.4 (10BASE2). These documents define jabber as the condition where any packet exceeds 20 ms. The allowed range to detect jabber is between 20 ms and 150 ms.

Fragment frames

The total number of packets received that were less than 64 octets in length (excluding framing bits, but including FCS octets), and had either an FCS error an alignment error.

Note that it is entirely normal for fragment frames to increment because both runts (which are normal occurrences due to collisions) and noise hits are counted.

Autonegotiation is the process that connected Ethernet interfaces use to communicate the information necessary to interoperate. Table 6 explains the autonegotiation information of the show interface interface-name extensive command output.

Table 6: Autonegotiation Information

Autonegotiation Field Information

Explanation

Negotiation status: Incomplete

The Negotiation status field shows Incomplete when the Ethernet interface has the speed or link mode configured.

Negotiation status: No autonegotiation

The Negotiation status field shows No autonegotiation when the remote Ethernet interface has the speed or link mode configured, or does not perform autonegotiation.

Negotiation status: Complete

Link partner status: OK

The Negotiation status field shows Complete and the Link partner field shows OK when the Ethernet interface is connected to a device that performs autonegotiation and the autonegotiation process completes successfully.

Link partner: Half-duplex

The Link partner field can be Full-duplex or Half-duplex depending on the capability of the attached Ethernet device.

Flow control: Symmetric/asymmetric

The Flow control field displays the types of flow control supported by the remote Ethernet device.



Monitor Statistics for a Fast Ethernet or Gigabit Ethernet Interface

Purpose

To monitor statistics for a Fast Ethernet or Gigabit Ethernet interface, use the following Junos OS CLI operational mode command:

Action

Caution

We recommend that you use the monitor interface fe-fpc/pic/port or monitor interface ge-fpc/pic/port command only for diagnostic purposes. Do not leave these commands on during normal router operations because real-time monitoring of traffic consumes additional CPU and memory resources.

Sample Output

The following sample output is for a Fast Ethernet interface:

Meaning

Use the information from this command to help narrow down possible causes of an interface problem.

Note

If you are accessing the router from the console connection, make sure you set the CLI terminal type using the set cli terminal command.

The statistics in the second column are the cumulative statistics since the last time they were cleared using the clear interfaces statistics interface-name command. The statistics in the third column are the cumulative statistics since the monitor interface interface-name command was executed.

If the input errors are increasing, verify the following:

  1. Check the cabling to the router and have the carrier verify the integrity of the line. To verify the integrity of the cabling, make sure that you have the correct cables for the interface port. Make sure you have single-mode fiber cable for a single-mode interface and multimode fiber cable for a multimode interface.

  2. For a fiber-optic connection, measure the received light level at the receiver end and make sure that it is within the receiver specification of the Ethernet interface. See Fiber-Optic Ethernet Interface Specifications for the fiber-optic Ethernet interface specifications.

  3. Measure the transmit light level on the Tx port to verify that it is within specification. See Fiber-Optic Ethernet Interface Specificationsfor the optical specifications.

Fiber-Optic Ethernet Interface Specifications

Table 7 shows the specifications for fiber-optic interfaces for Juniper Networks routers.

Table 7: Fiber-Optic Ethernet Interface Specifications

Fiber-Optic Ethernet Interface

Length

Wavelength

Average Launch Power

Receiver Saturation

Receiver Sensitivity

Gigabit Ethernet

Duplex SC connector

 

LH optical interface

49.5-mile 70-km reach on 8.2-micrometer SMF

1480 to 1580 nm

-3 to +2 dBm

-3 dBm

-23 dBm (BER 1012) for SMF

LX optical interface

6.2-mile 10-km reach on 9/125-micrometer SMF

1804.5-ft 550-m reach on 62.5/125- and 50/125-micrometer MMF

1270 to 1355 nm

-11 to -3 dBm

-3 dBm

-19 dBm

SX optical interface

656-ft 200-m reach on 62.5/125-micrometer MMF

1640-ft 500-m reach on 50/125-micrometer MMF

830 to 860 nm

-9.5 to -4 dBm

-3 dBm

-17 dBm

Fast Ethernet 8-Port

FX optical interface with MT-RJ connector

1.24-mile 2-km reach on 62.5/125-micrometer MMF

1270 to 1380 nm

-20 to -14 dBm

-14 dBm

-34 dBm