Locate LINK Alarms and Counters for Fast and Gigabit Ethernet
Learn how to locate, display LINK alarms and counters for Fast Ethernet and Gigabit Ethernet interfaces.
Checklist: Find LINK Alarms and Counters for Ethernet
Purpose
To find LINK alarm and major counters associated with Fast Ethernet and Gigabit Ethernet interfaces.
Action
Table 1 provides links and commands for locating LINK alarm and major counters for Fast Ethernet and Gigabit Ethernet interfaces.
Tasks |
Command or Action |
|---|---|
| Display LINK Alarms on Fast and Gigabit Ethernet | |
| Fast Ethernet and Gigabit Ethernet Counters |
It displays the major counters that appear in the output for the
|
Display LINK Alarms on Fast and Gigabit Ethernet
Problem
To display the Fast Ethernet or Gigabit Ethernet LINK alarm, use the following Junos OS command-line interface (CLI) operational mode command:
Cause
A LINK alarm on Fast Ethernet or Gigabit Ethernet interfaces typically indicates a physical layer issue. This could be due to reasons, such as a disconnected cable, faulty hardware, or a mismatch in speed and duplex settings between connected devices. Identifying the cause of the LINK alarm is crucial to maintain network stability and to ensure communication across the network.
Solution
user@host> show interfaces (fe-fpc/pic/port |ge-fpc/pic/port) extensive
Sample Output
The following sample output is for a Fast Ethernet interface:
user@host> show interfaces fe-1/3/3 extensive
Physical interface: fe-1/3/3, Enabled, Physical link is Down
Interface index: 47, SNMP ifIndex: 38
Description: Test
Link-level type: Ethernet, MTU: 1514, Source filtering: Disabled
Speed: 100mbps, Loopback: Disabled, Flow control: Enabled
Device flags : Present Running
Interface flags: SNMP-Traps
Link flags : None
Current address: 00:90:69:8d:2c:de, Hardware address: 00:90:69:8d:2c:de
Statistics last cleared: 2002-01-11 23:03:09 UTC (1w2d 23:54 ago)
Traffic statistics:
Input bytes : 373012658 0 bps
Output bytes : 153026154 1392 bps
Input packets: 1362858 0 pps
Output packets: 1642918 3 pps
Input errors:
Errors: 0, Drops: 0, Framing errors: 0, Runts: 0, Policed discards: 503660
L3 incompletes: 1 , L2 channel errors: 0, L2 mismatch timeouts: 0
FIFO errors: 0
Output errors:
Carrier transitions: 0, Errors: 0, Collisions: 0, Drops: 0, Aged packets: 0
HS link CRC errors: 0, FIFO errors: 0
Active alarms : LINK
Active defects : LINK
MAC statistics: Receive Transmit
Total octets 439703575 177452093
Total packets 1866532 1642916
Unicast packets 972137 1602563
Broadcast packets 30 2980
Multicast packets 894365 37373
CRC/Align errors 0 0
FIFO errors 0 0
MAC control frames 0 0
MAC pause frames 0 0
Oversized frames 0
Jabber frames 0
Fragment frames 0
VLAN tagged frames 0
Code violations 0
Filter statistics:
Input packet count 1866532
Input packet rejects 0
Input DA rejects 503674
Input SA rejects 0
Output packet count 1642916
Output packet pad count 0
Output packet error count 0
CAM destination filters: 5, CAM source filters: 0
Autonegotiation information:
Negotiation status: Complete, Link partner status: OK
Link partner: Full-duplex, Flow control: None
PFE configuration:
Destination slot: 1, Stream number: 15
CoS transmit queue bandwidth:
Queue0: 95, Queue1: 0, Queue2: 0, Queue3: 5
CoS weighted round-robin:
Queue0: 95, Queue1: 0, Queue2: 0, Queue3: 5
Logical interface fe-1/3/3.0 (Index 8) (SNMP ifIndex 69)
Description: Test
Flags: SNMP-Traps, Encapsulation: ENET2
Protocol inet, MTU: 1500, Flags: None
Addresses, Flags: Is-Preferred Is-Primary
Destination: 10.115.107.192/29, Local: 10.115.107.193
Broadcast: 10.115.107.199
Meaning
The sample output shows where the alarm and other errors might be occurring and any counters that are incrementing. The only alarm associated with Fast Ethernet or Gigabit Ethernet interfaces is the LINK alarm. A LINK alarm indicates a physical problem. To isolate where the physical problem might be occurring, conduct loopback testing. See Checklist to Use Loopback Test for Fast and Gigabit Ethernet Interfaces for information on conducting a loopback test.
Because link status is polled once every second, certain features or mechanisms that require fast link down detection, such as Multiprotocol Label Switching (MPLS) fast reroute, take longer to execute.
Fast Ethernet and Gigabit Ethernet Counters
Problem
Table 2 shows the
major counters that appear in the output for the show interfaces
fe-fpc/pic/port
extensive and the show interfaces
ge-fpc/pic/port
extensive commands. These counters generally increment when
there is a problem with a Fast Ethernet or Gigabit Ethernet interface. In the
Counters column, the counters are listed in the order in which
they are displayed in the output.
Cause
The counters typically increment due to issues like hardware faults, physical connection problems, incorrect configurations, or excessive network traffic. These increments indicate underlying problems with the Ethernet interface that need further investigation.
Solution
Counter |
Description |
Reason for Increment |
|---|---|---|
| Input Errors: | ||
|
The sum of the incoming frame terminates and frame check sequence (FCS) errors. |
The incoming errors counter increases when there are issues with the integrity of received frames, such as incomplete frame terminations or frame check sequence (FCS) errors, indicating potential problems like transmission errors, hardware issues, or network congestion. |
|
The frames discarded by the incoming packet match code. |
The frames were discarded because they were not recognized or of interest. Usually, this field reports protocols that the Junos OS does not handle. |
|
The number of packets dropped by the output queue of the I/O Manager application-specific integrated circuit (ASIC). |
If the interface is saturated, this number increments once for every packet that is dropped by the ASIC’s random early detection (RED) mechanism. |
|
The number of packets discarded due to the packets failing Layer 3 header checks. |
This counter increments when the incoming packet fails Layer 3 (usually IPv4) checks of the header. For example, a frame with less than 20 bytes of available IP header would be discarded and this counter would increment. |
|
The errors that occur when the software could not find
a valid logical interface (such as |
This error increments when, for example, a lookup for a virtual LAN (VLAN) fails. |
|
The count of malformed or short packets. |
The malformed or short packets cause the incoming packet handler to discard the frame and be unreadable. |
|
The number of first in, first out (FIFO) errors in the receive direction as reported by the ASIC on the Physical Interface Card (PIC). |
The value in this field should always be 0. If this value is not zero, cabling could be badly organized or the PIC could be broken. |
| Output Errors | ||
|
The sum of outgoing frame terminates and FCS errors. |
The outgoing errors counter increments when frames sent from the device have improper terminations or FCS errors, usually caused by hardware faults, incorrect configurations, or transmission issues during the forwarding process. |
|
The number of Ethernet collisions. |
The Fast Ethernet PIC supports only full-duplex operation, so this number should always remain 0. If it is incrementing, there is a software bug. |
|
The number of packets dropped by the output queue of the I/O Manager ASIC. |
If the interface is saturated, this number increments once for every packet that is dropped by the ASIC’s RED mechanism. |
|
The number of packets that remained in shared packet SDRAM for so long that the system automatically purged them. |
The value in this field should never increment. If it increments, it is probably a software bug or broken hardware. |
|
The number of errors on the high-speed links between the ASICs responsible for handling the router interfaces. |
The value in this field should always be 0. If it increments, either the FPC or the PIC is broken. |
| Miscellaneous Counters | ||
|
The number of packets that the filter rejected because the destination Media Access Control (MAC) address of the packet is not on the accept list. |
It is normal for this value to increment. When it increments very quickly and no traffic is entering the router from the far-end system, either there is a bad Address Resolution Protocol (ARP) entry on the far-end system, or multicast routing is not on and the far-end system is sending many multicast packets to the local router (which the router is rejecting). |
|
The number of packets that the filter padded to the minimum Ethernet size (60 bytes) before giving the packet to the MAC hardware. |
Usually, padding is done only on small ARP packets, but some very small Internet Protocol (IP) packets can also require padding. If this value increments rapidly, either the system is trying to find an ARP entry for a far-end system that does not exist, or it is misconfigured. |
|
Number of packets with an indicated error that the filter was given to transmit. |
These packets are usually aged packets or are the result of a bandwidth problem on the FPC hardware. On a normal system, the value of this field should not increment. |
|
The number of entries in the content-addressable memory (CAM) dedicated to destination and source MAC address filters. |
There can be up to 64 source entries. If source filtering is disabled, which is the default, the value for these fields should be 0. |