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V-30617

The administrator must ensure that the maximum hop limit is at least 32.

Finding ID
NET-IPV6-059
Rule ID
SV-40389r1_rule
Severity
Cat III
CCE
(None)
Group Title
Maximum hop limit is less than 32
CCI
(None)
Target Key
(None)
Documentable
No
Discussion

The Neighbor Discovery protocol allows a hop limit value to be advertised by routers in a Router Advertisement message to be 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 hop limit reaching zero before the packets sent by a host reached its destination.

Fix Text

Configure maximum hop limit to at least 32.

Check Content

The maximum number of hops used in router advertisements and all IPv6 packets that are originated by the router can be set using the ipv6 hop-limit command in global configuration mode. Review the router or multi-layer switch configuration to determine if the maximum hop limit has been configured. If it has been configured, then it must be set to at least 32. The following global command sets the max hop limit to 128: ipv6 hop-limit 128 Note: The IOS default is 64. Hence, if the hop limit is not configured, the router will be in compliance with the requirement.

Responsibility

Information Assurance Officer