138 Brocade ICX 6650 Administration Guide
53-1002600-01
Limiting the number of hops an IPv6 packet can traverse
5
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-route form 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.