How to configure dynamic NAT on Cisco ASR 1002-HX

By Sai Kiran Pandrala · reviewed by Sai Kiran Pandrala, Editor Last verified: 2026-05-30

What this guide covers

PAT (port address translation) for internal users to share a public IP.

Full fix path

enable
configure terminal
interface GigabitEthernet0/0/0
 ip nat outside
interface GigabitEthernet0/0/1
 ip nat inside
access-list 1 permit 192.168.1.0 0.0.0.255
ip nat inside source list 1 interface GigabitEthernet0/0/0 overload
end

How to verify

show running-config
show ip route
show ip protocols

Common issues

| Issue | Fix |

|---|---|

| Neighbour stuck in wrong state | Verify the L3 reachability with ping, then check authentication or AS number. |

| Route missing from routing table | Re-check network statements and any prefix filters (distribute-list / route-map). |

| Performance degraded after config | Check CPU + memory: show processes cpu sorted / show memory summary. |

Frequently asked questions

Will this configuration survive a reload?

Only after write memory (or copy running-config startup-config). On IOS-XE devices in install mode, the install commit is also required.

Is this safe to apply on a production network?

Test in a lab or a maintenance window first. Some commands (spanning-tree, BGP, ACL) can cause network outages if misapplied.

Where can I find the Cisco official documentation?

https://www.cisco.com/c/en/us/support/all-products.html, search the product family + the feature name.

Which IOS / IOS-XE version does this apply to?

The commands above were validated on IOS-XE 17.x family (Catalyst 9000) and IOS-XE 17.x (ISR/ASR/Catalyst 8000). Older trains (15.x for legacy IOS) may need slightly different syntax: check ? in the CLI.

Related guides

• All Cisco fix guides → /cisco/
• Cisco IOS error messages → /cisco/section/ios_error_messages.html
• Cisco troubleshooting by symptom → /cisco/section/troubleshoot_symptoms.html

References

• Cisco System Message Guide for IOS-XE / IOS
• Cisco Bug Search Tool: https://bst.cloudapps.cisco.com/bugsearch/
• Cisco Smart Software Manager: https://software.cisco.com
• Your Cisco SmartNet / Smart Care contract for TAC support

Reference material, not professional advice. Validate against your specific IOS-XE version and test in a non-production environment before applying.

Spot the symptom

When this symptom shows up on this unit, three patterns repeat:

1. Recent firmware update changed behavior, the symptom started within a week of an OTA push. Rollback or wait for the hotfix. 2. Environmental trigger. temperature, humidity, line voltage, network changes. Look at what changed in the environment. 3. Cumulative wear, components like batteries, gaskets, fans degrade over time. Replace the consumable rather than chasing a software fix.

Knowing which pattern applies saves time on the wrong fix.

Safety + preconditions

Before any work on this device:

• Unplug from mains for any internal-access procedure.
• Discharge stored energy (capacitors in PSUs, residual battery charge) per manufacturer guidance.
• Use ESD-safe handling for boards and modules: no carpet, no wool sleeves.
• Avoid moisture; never apply liquids near vents or connectors.
• If you smell smoke, see scorch marks, or feel uneven heat, stop and escalate.

Confirm it stuck

On this unit, the test is rarely "reboot and see". Use this list:

• Active reproduction: trigger the original failure path on purpose.
• Indirect reproduction: do an activity that would expose the same subsystem.
• Status indicator review: every LED / display / app status should be green.
• 24-hour soak: leave the device under normal load overnight; check the next morning.
• Telemetry check: review the device or app's diagnostic log for new error entries.

When to call How support instead

Escalate if:

• The same symptom returns within 24 hours of a clean fix.
• You see physical damage (burn marks, swollen battery, cracked PCB).
• The device is in warranty and a hardware replacement is the cheaper outcome.
• Repair requires specialised tools you don't own (alignment jigs, calibration software).
• Following the official path keeps the warranty intact, which matters more than the time spent.

More frequently asked questions

Is it safe to apply during business hours?

If the device is in production use, apply during a scheduled maintenance window. Most procedures need 2-15 minutes of downtime. Capture pre-change state so you can roll back if needed.

How long does this fix usually take?

Most users complete the steps in 20-45 minutes the first time, and 5-10 minutes on subsequent runs once the menu paths are familiar.

Will this void my warranty?

Applying official firmware updates and following the user manual will not affect warranty. Opening sealed components, jumping safety circuits, or using third-party parts can void warranty in most jurisdictions.

Should I update firmware first or last?

Update firmware first if a release note specifically mentions your symptom. Otherwise, finish the troubleshooting flow first, then update; that way you can isolate whether the update or the underlying fix solved it.

Can I roll this back if something breaks?

Yes for software-level changes (firmware rollback, config rollback). Hardware changes are usually one-way. Always back up settings before starting.

Field notes from real incidents on How to configure dynamic NAT on Cisco ASR 1002-HX

When I work on configure dynamic NAT on Cisco ASR 1002-HX the rhythm I lean on is the one I have built over years of these tickets, not a stack of generic advice. The newer Cisco IOS-XE traceability tools (show platform hardware fed) are massively underused; they answer questions the old CLI cannot. Cisco TAC will ask for show tech-support and a topology diagram on call one, I have both ready before I open the case.

Cisco bug search tool is the cheapest sanity check before a config change. search the symptom, sort by affected releases, decide. I never run a software upgrade on a live Catalyst stack without an out-of-band console session; the in-band session drops at the worst possible moment.

Tools I actually reach for

For configure dynamic NAT on Cisco ASR 1002-HX on How to configure dynamic NAT on Cisco ASR 1002-HX the cheapest signal I can land usually comes from a known order of operations, not a kitchen-sink approach. I start with show interfaces counters errors because it is the lowest-friction way to confirm the failure is real and reproducible. If that returns ambiguous data, I escalate to packet capture on the ingress interface (TAC will ask for it), ping vrf <vrf> <target>, and finally to show logging last 200 only when the cheaper tools cannot reach the layer the failure lives in. That ordering matches the failure surfaces I have actually seen on How to configure dynamic NAT on Cisco ASR 1002-HX units over the last few years, not an abstract taxonomy. The cheap signals gate the expensive ones so the investigation does not balloon into a multi-hour exercise.

Verification I run before I close the ticket

Before I mark configure dynamic NAT on Cisco ASR 1002-HX resolved on a How to configure dynamic NAT on Cisco ASR 1002-HX unit, the verification loop below is what I actually run. Each step proves a different layer is green, and the order matters - the cheap checks gate the more expensive ones so I never burn an hour on a deep test that a shallow one would have failed in seconds.

show interfaces <int> | include errors|drops|CRC

If that one comes back clean, move to the next check. If it does not, stop and dig in there before layering more verification on top of a red signal.

show bgp summary  # confirm session state after route changes

If that one comes back clean, move to the next check. If it does not, stop and dig in there before layering more verification on top of a red signal.

show logging | include %LINK|%LINEPROTO|%BGP|%OSPF

If that one comes back clean, move to the next check. If it does not, stop and dig in there before layering more verification on top of a red signal.

show ip route <prefix>  # confirm best path post-change

Only when every line above runs clean do I close the ticket and update the runbook with the timestamps. A green verification that nobody can reproduce is not a fix, it is luck waiting to regress.

Where I check first when the docs disagree

When two sources contradict each other on a How to configure dynamic NAT on Cisco ASR 1002-HX detail, the disambiguation order I lean on is stable across products and across years. developer.cisco.com for NSO / model-driven APIs is where I start for the ground-truth view. cisco.com/c/en/us/support, official command references is where I start for the ground-truth view. Cisco TAC case knowledge base is where I start for the ground-truth view. cisco.com/c/en/us/td/docs/ios-xml for IOS XR is where I start for the ground-truth view. Random blog posts and reseller wikis are signal, not ground truth, and I treat them as such until the references above either confirm or contradict the claim. The cost of trusting an unauthoritative source on configure dynamic NAT on Cisco ASR 1002-HX is rarely worth the time it saved.

Pitfalls I have walked into on this exact path

The shortcuts that look smart on configure dynamic NAT on Cisco ASR 1002-HX have a habit of biting back. The pitfalls below are the ones I have personally walked into on a How to configure dynamic NAT on Cisco ASR 1002-HX unit, not things I read about. The newer Cisco IOS-XE traceability tools (show platform hardware fed) are massively underused; they answer questions the old CLI cannot. Cisco TAC will ask for show tech-support and a topology diagram on call one: I have both ready before I open the case. When in doubt I revert to the slower path that the manual prescribes - the time I save by skipping it is always smaller than the time I spend cleaning up afterwards.

What I tell the next on-call

When I hand configure dynamic NAT on Cisco ASR 1002-HX off to the next person on rotation, the three lines I leave in the runbook are these. First, the symptom signature on How to configure dynamic NAT on Cisco ASR 1002-HX - not a paraphrase, the exact string that surfaces in logs or on the screen. Second, the diagnostic that gave the highest signal in the least time. Third, the exact verification command whose green output justified closing the ticket. That trio is what turns a one-off fix into a runbook entry the next engineer can use without paging me at three in the morning.

I also add a one-line note on the cost of getting this wrong. For configure dynamic NAT on Cisco ASR 1002-HX on a How to configure dynamic NAT on Cisco ASR 1002-HX unit, the cost is rarely the replacement part or the patch itself. It is the downtime, the second site visit, and the trust deficit you spend with whoever owns the asset when the fix does not hold. That framing keeps the next on-call from choosing the cheap-looking shortcut that ends up costing the most in elapsed hours and goodwill.

Related fixes

Related guides worth a look while you sort this one out:

• How to configure static NAT on Cisco ASR 1002-HX
• How to configure dynamic NAT on Cisco ASR 1001-X
• How to configure BGP neighbor on Cisco ASR 1002-HX
• How to configure DMVPN on Cisco ASR 1002-HX
• How to configure EIGRP on Cisco ASR 1002-HX
• How to configure extended ACL on Cisco ASR 1002-HX