Dell SmartFabric OS10 User Guide Release 10.5.3

IPv6 Routing Header Type 0

Routing header is an extension header that is defined in RFC 2460 for IPv6. A source uses routing header to list one or more intermediate nodes that a packet takes to reach its destination. Routing header is modeled similar to the IPv4 Loose Source and Route IP options. It consists of routing type field, which further identifies the extension.

The Type 0 routing header extension (RH0) is used for listing the addresses of the intermediate nodes for the packet to take to reach its destination. RH0 can also be used to perform denial of service attacks, bypassing filtering and firewall devices, and other kinds of security attacks. This extension is depreciated in RFC 5095. OS10 switches are compliant with RFC 5095. You can use the following command to drop all IPv6 packets with RH0 in case there is any noncompliant router or node in the network:

[no] ipv6 routing-header-type0 deny fast-path [slow-path]

Restrictions and Limitations

IPv6 RH0 packets are not dropped in hardware (fast-path) in the following scenarios:

• IPv6 RH0 packets for which Routing Header is present beyond first 128 bytes of the packet.
• IPv6 RH0 packets matching a Policy-Based Routing (PBR) entry is routed and not dropped.
• IPv6 RH0 packets with hop-by-hop header are not dropped when the ipv6 hop-by-hop CLI configuration is present. This restriction can be overcome using the slow-path parameter.