Illustrated TCP/IP by Matthew G. Naugle Wiley Computer Publishing, John Wiley & Sons, Inc. ISBN: 0471196568   Pub Date: 11/01/98

Chapter 173
RIPng

The packet format is shown in the slide and it is represented by RFC 2080. Notice that the same amount of space is taken up for the route table entries as IPv4 (160 bits per entry). One feature that was added extended the packet size to beyond the limit of 576 bytes as in RIPv1 and v2. It was noted that these update packets will never traverse a router, and therefore the limit on the Route Table Entries (RTE) is simply limited by the MTU of the medium over which the protocol is being used.

The formula is:

# of RTE = (MTU - sizeof(IPv6_hdrs) - UDP_hdrlen - RIPng_hdrlen)) / RTE_Size

The 8-bit subnet mask is used to identify the number of bits in the prefix. Since there are 8 bits, this gives us the capability of a 256-bit prefix, which is more than enough for the 128 bits of IPv6.

Legend

•  hdrs – headers

•  hdrlen – header length

RIPng