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EIGRPPrivileged EXEC

show ip eigrp traffic

Displays EIGRP packet statistics including sent/received counts for each packet type, used to verify EIGRP neighbor communication and troubleshoot packet loss or authentication issues.

Definition: show ip eigrp traffic is a Cisco IOS privileged exec command. Displays EIGRP packet statistics including sent/received counts for each packet type, used to verify EIGRP neighbor communication and troubleshoot packet loss or authentication issues.

Overview

The 'show ip eigrp traffic' command is a diagnostic tool in Cisco IOS that displays packet statistics for Enhanced Interior Gateway Routing Protocol (EIGRP). It provides a breakdown of sent and received packets by type (Hello, Update, Query, Reply, Ack, SIA Query, SIA Reply) and includes counts for total packets, checksum errors, and authentication failures. This command is essential for verifying EIGRP neighbor communication, identifying packet loss, and troubleshooting authentication mismatches or network congestion.

Unlike 'show ip eigrp neighbors', which shows neighbor state and uptime, 'show ip eigrp traffic' focuses on the health of the control plane traffic between routers. It is particularly useful when neighbors are flapping or when routing updates are not being exchanged. The command runs in privileged EXEC mode (enable) and does not affect the running configuration.

Output is buffered and may be cleared with 'clear ip eigrp traffic'. It is available in IOS 12.x and later, including IOS-XE, but not in NX-OS (which uses 'show ip eigrp traffic' with different output format) or IOS-XR (which lacks this command). Understanding this command helps network engineers isolate issues such as one-way communication, authentication errors, or excessive retransmissions, which are common in large-scale EIGRP deployments.

Syntax·Privileged EXEC
show ip eigrp traffic

When to Use This Command

  • Verify EIGRP hello packets are being exchanged between neighbors after configuration
  • Troubleshoot EIGRP neighbor adjacency failures by checking for packet drops or authentication errors
  • Monitor EIGRP traffic volume to identify potential network issues or misconfigurations
  • Confirm EIGRP route updates are being sent and received correctly

Parameters

ParameterSyntaxDescription
vrfvrf vrf-nameSpecifies the VRF instance for which to display EIGRP traffic statistics. If omitted, the default VRF is used. Common mistake: forgetting to specify VRF when multiple VRFs are configured, leading to misleading output.
autonomous-system<1-65535>The EIGRP autonomous system number. If omitted, statistics for all EIGRP processes are displayed. Common mistake: using the wrong AS number when multiple EIGRP processes exist.

Command Examples

Basic EIGRP traffic statistics

show ip eigrp traffic
IP-EIGRP Traffic Statistics for AS 100
  Hellos sent/received: 1500/1498
  Updates sent/received: 25/23
  Queries sent/received: 2/2
  Replies sent/received: 2/2
  Acks sent/received: 27/25
  Input queue high water mark: 2, 0 drops
  SIA-Queries sent/received: 0/0
  SIA-Replies sent/received: 0/0
  Hello process ID: 123
  PDM process ID: 456
  IP Socket queue: 0/2000 (current/max)
  Hello Timer: 5 secs

This output shows EIGRP packet counters for AS 100. 'Hellos sent/received' indicates neighbor discovery health; numbers should be roughly equal. 'Updates sent/received' shows route exchange activity. 'Queries' and 'Replies' indicate convergence events. 'Acks' are acknowledgments for reliable packets. 'Input queue high water mark' and 'drops' indicate congestion; zero drops is ideal. 'SIA' counters show stuck-in-active events (should be zero). 'Hello Timer' shows the configured hello interval.

EIGRP traffic with authentication errors

show ip eigrp traffic
IP-EIGRP Traffic Statistics for AS 100
  Hellos sent/received: 500/498
  Updates sent/received: 10/8
  Queries sent/received: 1/1
  Replies sent/received: 1/1
  Acks sent/received: 11/9
  Input queue high water mark: 5, 3 drops
  SIA-Queries sent/received: 0/0
  SIA-Replies sent/received: 0/0
  Authentication type errors: 2
  Authentication key errors: 1
  Hello process ID: 123
  PDM process ID: 456
  IP Socket queue: 0/2000 (current/max)
  Hello Timer: 5 secs

This output shows authentication errors: 'Authentication type errors: 2' and 'Authentication key errors: 1'. These indicate mismatched authentication configuration between neighbors. The input queue drops (3) may also be related to authentication failures. This helps pinpoint why EIGRP neighbors are not forming.

Understanding the Output

The 'show ip eigrp traffic' command provides a snapshot of EIGRP packet activity for a specific autonomous system. The 'Hellos sent/received' counters should be roughly equal; a significant disparity may indicate a one-way communication issue. 'Updates' reflect route changes; a high number could indicate flapping routes.

'Queries' and 'Replies' are used during convergence; excessive queries may suggest network instability. 'Acks' should correlate with updates and queries. The 'Input queue high water mark' shows the peak queue depth; persistent high values with 'drops' indicate congestion or slow processing.

'SIA' counters should be zero; non-zero values indicate stuck-in-active conditions. Authentication error counters appear only when EIGRP authentication is configured; any non-zero value indicates a problem. The 'Hello Timer' shows the configured hello interval (default 5 seconds for most interfaces).

Configuration Scenarios

Verify EIGRP neighbor communication after configuration

After configuring EIGRP on two routers, you need to confirm that Hello packets are being exchanged and that the neighbor relationship is established.

Topology

R1(Gi0/0)---10.0.12.0/30---(Gi0/0)R2

Steps

  1. 1.Step 1: On R1, enter privileged EXEC mode: enable
  2. 2.Step 2: Display EIGRP traffic statistics: show ip eigrp traffic
  3. 3.Step 3: Verify that Hello packets are being sent and received. Expected output shows non-zero counts for Hellos sent and received.
Configuration
! No configuration needed; this is a verification step.

Verify: show ip eigrp traffic Expected output snippet: EIGRP-IPv4 Traffic Statistics for AS 100 Hellos sent/received: 100/100 Updates sent/received: 5/5 Queries sent/received: 0/0 Replies sent/received: 0/0 Acks sent/received: 5/5 SIA-Queries sent/received: 0/0 SIA-Replies sent/received: 0/0 Hello process ID: 0 PDMs used: 0 IP-EIGRP Input queue: 0/2000 (current/max) IP-EIGRP Total queue length: 0

Watch out: If Hellos are sent but not received, check for ACLs blocking multicast 224.0.0.10 or mismatched EIGRP AS numbers.

Troubleshoot EIGRP authentication failure

EIGRP neighbors are flapping and you suspect authentication mismatch. Use 'show ip eigrp traffic' to check for authentication errors.

Topology

R1(Gi0/0)---10.0.12.0/30---(Gi0/0)R2

Steps

  1. 1.Step 1: On R1, enter privileged EXEC mode: enable
  2. 2.Step 2: Display EIGRP traffic statistics: show ip eigrp traffic
  3. 3.Step 3: Look for 'Auth type mismatch' or 'Auth key mismatch' counters. Non-zero values indicate authentication problems.
Configuration
! Configure EIGRP authentication on both routers (example on R1):
Router(config)# key chain EIGRP_KEY
Router(config-keychain)# key 1
Router(config-keychain-key)# key-string cisco123
Router(config)# interface GigabitEthernet0/0
Router(config-if)# ip authentication mode eigrp 100 md5
Router(config-if)# ip authentication key-chain eigrp 100 EIGRP_KEY

Verify: show ip eigrp traffic Look for: Auth type mismatch: 0 Auth key mismatch: 0 If non-zero, authentication is misconfigured.

Watch out: Ensure both routers use the same key chain name and key string. Also verify that the authentication mode (MD5) matches.

Troubleshooting with This Command

When troubleshooting EIGRP issues, 'show ip eigrp traffic' is a first-line command to assess control plane health. A healthy output shows balanced sent/received counts for Hellos, Updates, Queries, Replies, and Acks. The Hello count should increment steadily; if Hellos are sent but not received, suspect a Layer 1/2 issue, ACL blocking 224.0.0.10, or a mismatched EIGRP AS number.

If Hellos are received but Updates are not, check for route filtering or passive interfaces. Focus on the 'Errors' section: 'Checksum errors' indicate data corruption (bad link), 'Auth type mismatch' and 'Auth key mismatch' indicate authentication configuration errors. 'Retransmission count' (not directly shown but inferred from Update/Reply counts) can indicate packet loss.

A step-by-step diagnostic flow: 1) Check neighbor state with 'show ip eigrp neighbors'. If neighbors are not up, run 'show ip eigrp traffic' to see if Hellos are exchanged. 2) If Hellos are sent but not received, verify multicast reachability with 'ping 224.0.0.10' and check ACLs. 3) If Hellos are exchanged but neighbors flap, look for authentication errors or checksum errors. 4) If neighbors are up but routes missing, check Update counts: if Updates sent are high but received low, suspect one-way communication. Correlate with 'debug eigrp packets' to see actual packet contents, but use caution in production.

Also correlate with 'show ip eigrp interfaces' to verify interface parameters. The command 'clear ip eigrp traffic' resets counters, useful for isolating transient issues. In summary, 'show ip eigrp traffic' provides a quantitative view of EIGRP packet exchange, enabling rapid identification of common problems like authentication mismatch, packet loss, or one-way communication.

CCNA Exam Tips

1.

CCNA exam tip: Know that 'show ip eigrp traffic' is used to verify EIGRP neighbor communication; if Hellos are not incrementing, check interface and network statements.

2.

CCNA exam tip: Understand that 'drops' in the input queue indicate that the router is overwhelmed; this can cause neighbor flapping.

3.

CCNA exam tip: Remember that authentication errors are displayed in this command; non-zero values mean EIGRP authentication is misconfigured.

4.

CCNA exam tip: Be aware that SIA counters should be zero; non-zero values indicate a stuck-in-active condition, often due to a lost query or reply.

Common Mistakes

Mistake 1: Assuming that if Hellos are sent, the neighbor is fully adjacent; Hellos only indicate neighbor discovery, not full adjacency (must also see routes).

Mistake 2: Ignoring input queue drops; even a few drops can cause neighbor flapping and should be investigated.

Mistake 3: Forgetting to specify the AS number if multiple EIGRP processes exist; use 'show ip eigrp 100 traffic' to filter.

show ip eigrp traffic vs show ip eigrp topology

Both 'show ip eigrp traffic' and 'show ip eigrp topology' are EIGRP diagnostic commands, but they address different aspects: traffic statistics versus the route topology table. They are commonly confused because both are used to verify EIGRP operation, yet one focuses on packet-level communication while the other on route learning and path selection.

Aspectshow ip eigrp trafficshow ip eigrp topology
ScopePacket-level statisticsRoute-level topology
Data displayedSent/received counts per packet typeAll learned routes with metrics and successors
Configuration impactNone, read-only countersNone, read-only table
Typical useTroubleshoot neighbor communicationVerify path selection and convergence

Use show ip eigrp traffic when troubleshooting EIGRP neighbor issues, packet loss, or authentication mismatches.

Use show ip eigrp topology when verifying EIGRP route selection, feasible successors, or checking route stability.

Platform Notes

In IOS-XE (e.g., 16.x), the command syntax and output are identical to classic IOS. However, in IOS-XE, the output may include additional fields like 'IPv6' if EIGRP for IPv6 is configured. The NX-OS equivalent is 'show ip eigrp traffic' but with different formatting; NX-OS also supports 'show ip eigrp traffic detail' for more granular stats.

There is no ASA equivalent; ASAs run EIGRP only in routed mode and use the same command. In IOS 12.x, the output includes 'Hello process ID' and 'PDMs used' fields that are removed in later versions. IOS-XR does not support this command; instead, use 'show eigrp traffic' (note: no 'ip' keyword) with different output fields.

For IOS 15.x and later, the command supports VRF and AS parameters. Always ensure you are in privileged EXEC mode; the command is not available in user EXEC mode.

Related Commands

show ip eigrp interfaces

Displays detailed information about interfaces on which EIGRP is enabled, including neighbor status, pending routes, and interface statistics, used to verify EIGRP adjacency and interface participation.

show ip eigrp neighbors

Displays all EIGRP neighbours with their addresses, interfaces, hold time, uptime, SRTT (smooth round-trip time), RTO, queue count, and sequence numbers.

show ip eigrp topology

Displays the EIGRP topology table, showing all learned routes and their feasible successors, used to verify EIGRP convergence and path selection.

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