Dell C1048P Port Extender Networking Configuration Guide for the C9000 Series - Page 566

This field identifies the length of the Hop-by-Hop Options header in 8-byte units, but does not include the first 8 bytes. Consequently, if the header is less than 8 bytes, the value is 0 (zero). • Options (size varies) This field can contain one or more options. The first byte if the field identifies the Option type, and directs the router how to handle the option. 00 Skip and continue processing. 01 Discard the packet. 10 Discard the packet and send an ICMP Parameter Problem Code 2 message to the packet's Source IP Address identifying the unknown option type. 11 Discard the packet and send an ICMP Parameter Problem, Code 2 message to the packet's Source IP Address only if the Destination IP Address is not a multicast address. The second byte contains the Option Data Length. The third byte specifies whether the information can change en route to the destination. The value is 1 if it can change; the value is 0 if it cannot change. IPv6 Addressing IPv6 addresses are normally written as eight groups of four hexadecimal digits, where each group is separated by a colon (:). For example, 2001:0db8:0000:0000:0000:0000:1428:57ab is a valid IPv6 address. If one or more four-digit group(s) is 0000, the zeros may be omitted and replaced with two colons(::). For example, 2001:0db8:0000:0000:0000:0000:1428:57ab can be shortened to 2001:0db8::1428:57ab. Only one set of double colons is supported in a single address. Any number of consecutive 0000 groups may be reduced to two colons, as long as there is only one double colon used in an address. Leading and/or trailing zeros in a group can also be omitted (as in ::1 for localhost, 1:: for network addresses and :: for unspecified addresses). All the addresses in the following list are all valid and equivalent. • 2001:0db8:0000:0000:0000:0000:1428:57ab • 2001:0db8:0000:0000:0000::1428:57ab • 2001:0db8:0:0:0:0:1428:57ab • 2001:0db8:0:0::1428:57ab • 2001:0db8::1428:57ab • 2001:db8::1428:57ab IPv6 networks are written using classless inter-domain routing (CIDR) notation. An IPv6 network (or subnet) is a contiguous group of IPv6 addresses the size of which must be a power of two; the initial bits of addresses, which are identical for all hosts in the network, are called the network's prefix. A network is denoted by the first address in the network and the size in bits of the prefix (in decimal), separated with a slash. Because a single host is seen as a network with a 128-bit prefix, host addresses may be written with a following /128. IPv6 Routing 566