The Cisco switch must be configured to advertise a hop limit of at least 32 in Switch Advertisement messages for IPv6 stateless auto-configuration deployments.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-237754 | CISC-RT-000236 | SV-237754r999759_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 NX OS Switch RTR Security Technical Implementation Guide | 2024-12-20 | |||
Details
Check Text (C-237754r999759_chk)
Review the switch configuration to determine if the hop limit has been configured for Router Advertisement messages for all internal interfaces as shown in the example.
interface Ethernet2/1
no switchport
ipv6 address 2001::1:0:1/64
ipv6 nd hop-limit 32
no shutdown
interface Ethernet2/2
no switchport
ipv6 address 2001::1:1:1/64
ipv6 nd hop-limit 32
no shutdown
If hop-limit has been configured and has not been set to at least 32, it is a finding.
Fix Text (F-40934r999758_fix)
Configure the switch to advertise a hop limit of at least 32 in Router Advertisement messages as shown in the example.
SW1(config)# interface e2/1 – 2
SW1(config-if-range)# ipv6 nd hop-limit 32
SW1(config-if-range)# end