show ip route summary
Displays a summary of the IP routing table, including route counts by protocol and network prefixes.
Overview
The 'show ip route summary' command on Cisco NX-OS (Nexus) provides a high-level overview of the IP routing table, breaking down route counts by protocol source. It is essential for network engineers to quickly assess the routing table's composition, size, and memory footprint without viewing every individual route. This command is particularly useful in large-scale environments with multiple routing protocols and VRFs, where route leaks or unexpected redistribution can cause routing table bloat. On Nexus platforms, the command is VRF-aware, allowing per-VRF summaries. It fits into troubleshooting workflows as a first step to identify anomalies: for example, a sudden increase in OSPF routes might indicate a misconfigured redistribution or a flapping link. The output also includes memory usage per protocol, which helps in capacity planning and monitoring control-plane resource consumption. Unlike 'show ip route', which lists all routes, the summary view is lightweight and can be run frequently without performance impact.
show ip route summary [vrf vrf-name]When to Use This Command
- Quickly assess the size and composition of the routing table to identify unexpected route counts.
- Verify redistribution of routes between protocols (e.g., OSPF into BGP).
- Troubleshoot routing table bloat or missing routes in a VRF.
- Monitor route convergence after a network change.
Parameters
| Parameter | Syntax | Description |
|---|---|---|
| vrf vrf-name | vrf vrf-name | Specifies the VRF for which to display the route summary. If omitted, the default VRF is used. This parameter is essential in multi-VRF environments to isolate routing information per tenant or customer. |
Command Examples
Basic route summary
show ip route summaryIP Route Table for VRF "default" '*' denotes best ucast next-hop '**' denotes best mcast next-hop '[x/y]' denotes [preference/metric] Route Source Networks Subnets Overhead Memory (bytes) connected 2 0 0 320 static 1 0 0 160 application 0 0 0 0 bgp 10 5 0 2400 ospf 8 3 0 1760 isis 0 0 0 0 rip 0 0 0 0 eigrp 0 0 0 0 Total routes: 21 Total paths: 21
The output shows the VRF (default), route sources, number of networks and subnets per protocol, overhead, and memory usage. Total routes and paths are summarized at the bottom.
Route summary for a specific VRF
show ip route summary vrf CUSTOMER_AIP Route Table for VRF "CUSTOMER_A" '*' denotes best ucast next-hop '**' denotes best mcast next-hop '[x/y]' denotes [preference/metric] Route Source Networks Subnets Overhead Memory (bytes) connected 3 1 0 640 static 0 0 0 0 application 0 0 0 0 bgp 25 12 0 5920 ospf 0 0 0 0 isis 0 0 0 0 rip 0 0 0 0 eigrp 0 0 0 0 Total routes: 41 Total paths: 41
For VRF CUSTOMER_A, the table shows 3 connected networks (with 1 subnet), 25 BGP networks (with 12 subnets), totaling 41 routes. Memory usage is also displayed per protocol.
Understanding the Output
The output begins with the VRF name and legend. The main table lists each route source (connected, static, bgp, ospf, etc.) with columns: Networks (classful networks), Subnets (subnetted prefixes), Overhead (protocol-specific overhead), and Memory (bytes used). The 'Total routes' line sums all routes; 'Total paths' counts all next-hop paths (including ECMP). Healthy values show expected counts per protocol; a sudden spike in one protocol may indicate misconfiguration or route leak. Memory usage helps monitor resource consumption.
Configuration Scenarios
Verifying route redistribution into BGP
A network engineer has configured redistribution of OSPF routes into BGP. They want to confirm that OSPF routes appear in the BGP route table.
Topology
Nexus-1 (OSPF + BGP) --- ISP
|
+--- OSPF Area 0Steps
- 1.Configure OSPF redistribution into BGP under router bgp.
- 2.Run 'show ip route summary' to see OSPF and BGP route counts.
- 3.Compare counts before and after redistribution.
! router bgp 65000
address-family ipv4 unicast
redistribute ospf 1 route-map OSPF_TO_BGPVerify: After redistribution, the BGP route count in 'show ip route summary' should increase by the number of OSPF routes. Also check 'show ip bgp summary' for prefix counts.
Watch out: Ensure the route-map permits the desired OSPF routes; otherwise, redistribution may silently fail.
Troubleshooting with This Command
When troubleshooting routing issues on Cisco NX-OS (Nexus), 'show ip route summary' is a quick diagnostic tool. Start by checking the total route count: if it is unexpectedly high, suspect route leaks or misconfigured redistribution. Compare counts per protocol against known baselines. For example, if BGP routes are missing, verify BGP peering and prefix limits. If OSPF routes are missing, check OSPF neighbor states and area configuration. The memory column helps identify protocols consuming excessive memory, which could indicate route flapping or a large number of prefixes. In multi-VRF environments, always specify the VRF to isolate issues. Use this command in conjunction with 'show ip route vrf X' to drill down into specific routes. If the summary shows zero routes for a protocol that should have routes, check the protocol's operational status (e.g., 'show ip ospf', 'show ip bgp summary').
CCNA Exam Tips
Memorize that 'show ip route summary' is used to quickly see route counts per protocol, not route details.
Know that the command supports VRF filtering with 'vrf vrf-name'.
Understand that 'Total paths' can exceed 'Total routes' when ECMP is in use.
Common Mistakes
Confusing 'Networks' with 'Subnets' – Networks are classful prefixes, Subnets are VLSM prefixes.
Forgetting to specify VRF when troubleshooting a non-default VRF.
Assuming 'Total routes' equals number of routing table entries; it's the sum of all protocol routes, including duplicates.
Platform Notes
On Cisco NX-OS (Nexus), 'show ip route summary' is similar to the IOS command but with VRF support built-in. Unlike IOS, Nexus does not require '| include' to filter VRFs; the 'vrf' parameter is native. The output format is consistent across Nexus 9000, 7000, and 3000 series. In earlier NX-OS versions, the command might not show 'application' routes; this was added in later releases. Equivalent commands on other platforms: on Juniper Junos, 'show route summary' provides similar information; on Arista EOS, 'show ip route summary' is also available. Always use the latest NX-OS documentation for version-specific details.
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