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-230040	CISC-RT-000236	SV-230040r532994_rule		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 XR Router RTR Security Technical Implementation Guide	2020-09-23

Details

Check Text ( C-32352r531382_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-32329r531385_fix)
Configure the router to advertise a hop limit of at least 32 in Router Advertisement messages. R1(config)#ipv6 hop-limit 128