BGPEXEC

show bgp ipv4 unicast summary

Displays a summary of BGP IPv4 unicast peering sessions, including neighbor status, prefixes received, and memory usage.

Overview

The 'show bgp ipv4 unicast summary' command is a fundamental tool for monitoring and troubleshooting BGP sessions in Cisco IOS-XR. It provides a concise overview of all BGP IPv4 unicast peers, their current state, and key statistics. BGP (Border Gateway Protocol) is the de facto inter-domain routing protocol used to exchange routing information between autonomous systems (AS). In IOS-XR, BGP is fully modular and supports multiple address families, including IPv4 unicast. This command is typically the first step in verifying BGP peering after configuration changes or when diagnosing connectivity issues. It helps network engineers quickly identify neighbors that are down, flapping, or not receiving expected prefixes. The output includes the BGP router ID, local AS, table version, and per-neighbor details such as messages exchanged, queue depths, session uptime, and prefix count. In a troubleshooting workflow, if a route is missing, this command can confirm whether the neighbor is established and how many prefixes it has advertised. Platform-specific behavior in IOS-XR includes support for VRFs, multiple BGP instances, and detailed sub-modes. The command can be extended with 'detail' for granular information or filtered by VRF. Understanding this output is crucial for CCNP and CCIE candidates, as BGP is a core topic in these certifications.

Syntax·EXEC

show bgp ipv4 unicast summary [vrf vrf-name] [instance instance-name] [process] [detail]

When to Use This Command

Quickly verify BGP neighbor states and session uptime after configuration changes.
Monitor the number of prefixes received from each peer to detect route leaks or flapping.
Check memory usage of BGP process to identify potential resource exhaustion.
Troubleshoot BGP session flapping by reviewing counters for messages sent/received.

Parameters

Parameter	Syntax	Required	Description
vrf vrf-name	vrf vrf-name	Optional	Specifies the VRF (Virtual Routing and Forwarding) instance. Use this to view BGP summary for a specific VRF. If omitted, the global routing table is used.
instance instance-name	instance instance-name	Optional	Specifies a BGP instance name. In IOS-XR, multiple BGP processes can run; this parameter selects a particular instance. Default is the first instance.
process	process	Optional	Displays BGP process-level information such as memory usage and number of routes. Not commonly used in summary.
detail	detail	Optional	Provides additional details for each neighbor, including hold time, keepalive interval, message statistics, and reset history.

Command Examples

Basic BGP IPv4 Unicast Summary

show bgp ipv4 unicast summary

BGP router identifier 192.0.2.1, local AS number 65000
BGP table version: 12345, main routing table version 12345

Neighbor        V           AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd
10.0.0.1        4        65001    1000    1000    12345    0    0 1d02h         500
10.0.0.2        4        65002    2000    2000    12345    0    0 2d04h        1000
10.0.0.3        4        65003     500     500    12345    0    0 00:30:00     250
10.0.0.4        4        65004       0       0        0    0    0 never      Idle (Admin)

The first line shows the router ID and local AS. The table lists each neighbor: IP address, BGP version, remote AS, messages received/sent, table version, input/output queue depths, uptime, and state or prefix count. Neighbor 10.0.0.4 is administratively shutdown (Idle).

Detailed BGP Summary with VRF

show bgp ipv4 unicast summary vrf CUSTOMER-A detail

BGP router identifier 192.0.2.1, local AS number 65000
BGP table version: 5678, main routing table version 5678

Neighbor        V           AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd
10.1.1.1        4        65100    5000    5000    5678    0    0 5d12h        2000

For address family: IPv4 Unicast
  BGP neighbor 10.1.1.1, vrf CUSTOMER-A
  BGP version 4, remote AS 65100
  Using BGP dynamic listening
  Last reset: 5d12h, due to BGP Notification sent (Cease/Administrative Reset)
  Session: 10.1.1.1:179
  Hold time: 90, keepalive interval: 30 seconds
  Message statistics:
    Sent: 5000, Received: 5000
  Prefix statistics:
    Sent: 1500, Received: 2000
  Connection statistics:
    Established: 2, Dropped: 1
  Last reset never

This detailed output for a VRF shows additional fields: hold time, keepalive interval, prefix statistics (sent/received), connection establishment/drop counts, and last reset reason. The neighbor is stable with 2000 prefixes received.

Understanding the Output

The output begins with the BGP router ID and local AS number. The 'BGP table version' indicates the current version of the BGP table; it increments with each change. The main routing table version shows the version installed in the routing table. The neighbor table lists each BGP peer with columns: Neighbor (IP address), V (BGP version, typically 4), AS (remote AS), MsgRcvd/MsgSent (total messages exchanged), TblVer (table version last sent to that neighbor), InQ/OutQ (queue depths, should be 0 in steady state), Up/Down (session uptime or 'never' if never established), and State/PfxRcd (current state or number of prefixes received). A healthy session shows 'Established' or a number of prefixes; problem states include Idle, Active, Connect, or OpenSent. High InQ/OutQ values indicate congestion. A large discrepancy between MsgRcvd and MsgSent may indicate asymmetric routing or issues. The prefix count should be consistent with expected routes; sudden drops suggest route withdrawal or session reset.

Configuration Scenarios

Basic BGP Peering Setup

Two routers in different ASes establishing eBGP peering.

Topology

R1 (AS 65001) --- 10.0.0.0/30 --- R2 (AS 65002)

Steps

1.Configure BGP on R1 with neighbor 10.0.0.2 remote-as 65002.
2.Configure BGP on R2 with neighbor 10.0.0.1 remote-as 65001.
3.Verify with 'show bgp ipv4 unicast summary' on both routers.

Configuration

! R1 configuration
router bgp 65001
 bgp router-id 192.0.2.1
 address-family ipv4 unicast
  neighbor 10.0.0.2 remote-as 65002
  neighbor 10.0.0.2 activate
 !
!

Verify: On R1, 'show bgp ipv4 unicast summary' should show neighbor 10.0.0.2 in Established state with prefixes received.

Watch out: Ensure the neighbor is activated under the address-family; otherwise, the session may come up but no prefixes are exchanged.

BGP in a VRF

Service provider using VRF for customer isolation.

Topology

PE (AS 65000) --- CE (AS 65100) via VRF CUSTOMER-A

Steps

1.Create VRF CUSTOMER-A on PE.
2.Configure BGP VRF with neighbor under address-family ipv4 unicast vrf.
3.Verify with 'show bgp ipv4 unicast summary vrf CUSTOMER-A'.

Configuration

! PE configuration
vrf CUSTOMER-A
 rd 65000:100
!
router bgp 65000
 vrf CUSTOMER-A
  bgp router-id 192.0.2.1
  address-family ipv4 unicast
   neighbor 10.1.1.2 remote-as 65100
   neighbor 10.1.1.2 activate
  !
!

Verify: Use 'show bgp ipv4 unicast summary vrf CUSTOMER-A' to see the VRF-specific BGP summary.

Watch out: Forgetting to specify the VRF in the show command will display the global table, not the VRF.

Troubleshooting with This Command

When troubleshooting BGP issues with 'show bgp ipv4 unicast summary', start by checking the neighbor state. If a neighbor is in 'Idle' state, it could be due to an administrative shutdown (check 'neighbor shutdown' configuration), missing or incorrect remote-as, or a network reachability issue. 'Active' state means the router is trying to initiate a TCP connection; verify that the neighbor IP is reachable via ping and that there is no ACL blocking TCP port 179. 'Connect' state indicates the TCP connection is established but BGP open message not yet sent. 'OpenSent' and 'OpenConfirm' are transient states; if stuck, check for mismatched BGP capabilities or authentication. Once established, the 'State/PfxRcd' column shows the number of prefixes received. A sudden drop in prefix count may indicate route withdrawal or session reset; check the 'Up/Down' time to see if the session recently reset. High 'InQ' or 'OutQ' values suggest the BGP process is overwhelmed; this could be due to excessive route updates or memory pressure. The 'MsgRcvd' and 'MsgSent' counters should increment steadily; if they stop, the session may be stuck. In IOS-XR, you can also use 'show bgp ipv4 unicast summary detail' to see the last reset reason, which often points to the cause of flapping. For memory issues, check the 'process' parameter to see BGP memory usage. Always correlate with 'show ip route bgp' to verify that routes are installed in the routing table.

CCNA Exam Tips

Remember that 'Idle' state often indicates an administrative shutdown or missing neighbor configuration.

The 'Up/Down' column shows session uptime; a short uptime suggests flapping.

In IOS-XR, the 'show bgp ipv4 unicast summary' command is similar to IOS but uses 'ipv4 unicast' instead of 'ipv4'.

Common Mistakes

Confusing 'State/PfxRcd' column: when the session is established, it shows prefix count, not the state.

Forgetting to specify VRF when checking BGP in a VRF context; without VRF, only global table is shown.

Misinterpreting 'Idle (Admin)' as a protocol issue when it is an administrative configuration.

Platform Notes

In Cisco IOS-XR, the BGP implementation is modular and supports multiple BGP instances, VRFs, and advanced features like BGP FlowSpec. The 'show bgp ipv4 unicast summary' command is similar to Cisco IOS but uses the address-family keyword 'ipv4 unicast' instead of just 'ipv4'. In IOS, the equivalent command is 'show ip bgp summary'. IOS-XR also supports the 'detail' keyword for per-neighbor statistics, which is not available in classic IOS. Additionally, IOS-XR requires explicit activation of neighbors under the address-family; otherwise, the session may come up but no prefixes are exchanged. For VRFs, the command syntax includes 'vrf vrf-name' after the address family. In IOS, VRF BGP summary is shown with 'show ip bgp vpnv4 vrf vrf-name summary'. Another difference: IOS-XR uses 'router bgp' with AS number, and the BGP process is configured hierarchically. The output format is also slightly different; for example, IOS-XR shows 'BGP table version' and 'main routing table version' separately. For troubleshooting, IOS-XR provides more detailed reset reasons in the 'detail' output. Version differences: In IOS-XR 6.0 and later, the command supports additional parameters like 'instance' for multiple BGP processes. Always check the specific IOS-XR version documentation for exact syntax.

Practice for the CCNA 200-301

Test your knowledge with hundreds of CCNA practice questions covering all exam domains.

Practice CCNA Questions