The Cisco router must be configured to advertise a hop limit of at least 32 in Router Advertisement messages for IPv6 stateless auto-configuration deployments.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-230039 | CISC-RT-000236 | SV-230039r647454_rule | CCI-000366 | low |
| Description | ||||
| The Neighbor Discovery protocol allows a hop limit value to be advertised by routers in a Router Advertisement message being used by hosts instead of the standardized default value. If a very small value was configured and advertised to hosts on the LAN segment, communications would fail due to the hop limit reaching zero before the packets sent by a host reached its destination. | ||||
| STIG | Date | |||
| Cisco IOS XE Router RTR Security Technical Implementation Guide | 2025-05-16 | |||
Details
Check Text (C-230039r647454_chk)
Review the router configuration to determine if the hop limit has been configured for Router Advertisement messages as shown in the example.
ipv6 hop-limit 128
If it has been configured and has not been set to at least 32, it is a finding.
Fix Text (F-32329r647424_fix)
Configure the router to advertise a hop limit of at least 32 in Router Advertisement messages.
R1(config)#ipv6 hop-limit 128