Brocade FastIron Ethernet Switch Layer 3 Routing Configuration Guide - Manual (Page 192)

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.
device(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:
device(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.
TCAM space on FCX device configuration
FCX devices store routing information for IPv4 and IPv6 and GRE tunnel information in the same
TCAM table. You can configure the amount of TCAM space to allocate for IPv4 routing information
and GRE tunnels. The remaining space is allocated automatically for IPv6 routing information.
FCX devices have TCAM space to store 16,000 IPv4 route entries. Each IPv6 route entry and GRE
tunnel use as much storage space as four IPv4 route entries. The default, maximum, and minimum
allocation values for each type of data are shown in
TCAM space on FCX device configuration .
TCAM space allocation on FCX and ICX devices (except ICX 6450) TABLE 32
Default Maximum Minimum
IPv4 route entries 12000 15168 4096
IPv6 route entries 908 2884 68
Limiting the number of hops an IPv6 packet can traverse
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