Brocade Communications Systems 6650 manual Limiting the number of hops an IPv6 packet can traverse

5 Limiting the number of hops an IPv6 packet can traverse

If you attempt to add an entry that already exists in the neighbor discovery cache, the software changes the already existing entry to a static entry.

To remove a static IPv6 entry from the IPv6 neighbor discovery cache, use the no form of this command.

Limiting the number of hops an IPv6 packet can traverse

By default, the maximum number of hops an IPv6 packet can traverse is 64. You can change this value to between 0 – 255 hops. For example, to change the maximum number of hops to 70, enter the following command.

Brocade(config)#ipv6 hop-limit 70

Syntax: [no] ipv6 hop-limit <number>

Use the no form of the command to restore the default value. hop-limit 0 will transmit packets with default (64) hop limit. <number> can be from 0 – 255.

IPv6 source routing security enhancements

The IPv6 specification (RFC 2460) specifies support for IPv6 source-routed packets using a type 0 Routing extension header, requiring device and host to process the type 0 routing extension header. However, this requirement may leave a network open to a DoS attack.

A security enhancement disables sending IPv6 source-routed packets to IPv6 devices. (This enhancement conforms to RFC 5095.)

By default, when the router drops a source-routed packet, it sends an ICMP Parameter Problem (type 4), Header Error (code 0) message to the packet's source address, pointing to the unrecognized routing type. To disable these ICMP error messages, enter the following command:

Brocade(config)# no ipv6 icmp source-route

Syntax: [no] ipv6 icmp source-route

Use the ipv6 icmp source-routeform of the command to enable the ICMP error messages.

Clearing global IPv6 information

You can clear the following global IPv6 information:

•Entries from the IPv6 cache.

•Entries from the IPv6 neighbor table.

•IPv6 routes from the IPv6 route table.

•IPv6 traffic statistics.

138	Brocade ICX 6650 Administration Guide
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