The asr1000-rommon.173-1r.spa.pkg is only a few megabytes in size – dwarfed by the gigabyte-sized IOS XE images. Yet, without it or with a corrupt version, your ASR 1000 is a paperweight. This file is the first instruction the CPU executes, the digital handshake that brings line cards to life, and your lifeline when all else fails.
Whether you are running a global backbone or a regional aggregation point, verifying and upgrading your ASR 1000 series ROMMON to version 173-1r is a low-risk, high-reward maintenance task. Don’t wait for a boot failure to discover you are running outdated, buggy firmware.
Action Item: Next time you log into your ASR 1000, run show rom-monitor. If the version does not read 173-1r, plan your upgrade window today.
With the rise of hardware-level attacks, Cisco hardened later ROMMON versions. asr1000-rommon.173-1r.spa.pkg
From a compliance perspective (PCI-DSS, HIPAA), running unsupported or legacy ROMMON versions can be a violation. Always keep ROMMON updated per Cisco’s security advisories.
Production routers often run for years without a ROMMON update. However, specific scenarios demand it:
| Scenario | Why Upgrade to 17.3(1r) | |----------|--------------------------| | Hardware replacement | Newer supervisor or RP modules ship with older ROMMON. Upgrade ensures feature parity. | | IOS-XE upgrade beyond 17.9 | Newer bootloaders need improved memory initialization and SHA-512 image verification. | | Security vulnerabilities | Fixes for ROM-based attacks (e.g., ROMMON-1 bypass). | | USB boot support | Later ROMMON versions fix USB enumeration and file system read/write issues. | | TPM (Trusted Platform Module) | Required for secure boot and hardware anchoring. | The asr1000-rommon
Without this upgrade, you may see the following failure when booting a new IOS-XE:
%ROMMON-IMG-INVALID: Image checksum failed
%ROMMON-BOOT-FAIL: No valid boot image, falling back to rommon
asr1000-rommon.173-1r.spa.pkg is available to customers with a valid Cisco Smart Net Total Care contract:
Checksum verification (example SHA256):
openssl sha256 asr1000-rommon.173-1r.spa.pkg
Always compare against Cisco’s published value.
asr1000-rommon.173-1r.spa.pkg is a ROMMON (ROM Monitor) image package for Cisco ASR 1000 series routers. ROMMON images provide a low-level bootstrap environment used for hardware initialization, recovery, and for loading IOS-XE images when the main OS is unavailable or needs recovery. The 173-1r designation indicates a ROMMON build family/version that aligns with IOS-XE 17.3.x releases for ASR1000 platforms.
| Myth | Reality |
|------|---------|
| This file boots the router | No – IOS-XE packages like asr1000-universalk9.17.03.02.SPA.bin do. ROMMON only initializes hardware. |
| Higher version always better | Not if the hardware doesn’t support it. ROMMON 173-1r is not for RP1. |
| You can downgrade ROMMON | Usually yes via the same upgrade rom-monitor command, but some hardware revisions block downgrades below a security baseline. |
| It’s included in IOS-XE bundle | No – the .pkg is separate and must be downloaded from Cisco’s software portal. | With the rise of hardware-level attacks, Cisco hardened
If you are performing maintenance on a Cisco ASR 1000 Series router, you may have come across the file asr1000-rommon.173-1r.spa.pkg in your downloads or during a consolidated package upgrade.
This post breaks down what this file is, why it is critical for your router's health, and how to verify it is running correctly.