RFC1797

Your allocated with AS 0x315, use the corresponding Glop address to set the router ID for each router

So 0x315 is AS 789

Our Multicast Range is from 233.3.21.001 to 233.3.21.254

03 in hex == 2 in dec
15 in hex == 21 in dec

so the address used as the router ID would be: 233.3.21.0/24

The IANA should allocate 233/8. The remaining 24 bits will be administered as described in RFC1797:

Glop bit representation:

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 233 | 16 bits AS | local bits |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Consider, for exampe, AS 5662. Written in binary, left padded with 0s, we get 0001011000011110 Mapping the high order octet to the second octet of the address, and the low order octect to the the third octet, we get 233.22.30/24.

RFC 2770 proposes that the 233.0.0.0/8 address range be reserved for statically defined addresses by organizations that already have an AS number reserved. The AS number of the domain is embedded into the second and third octets of the 233.0.0.0/8 range.

For example, the AS 62010 is written in hex as F23A. Separating out the two octets F2 and 3A, we get 242 and 58 in decimal. This would give us a subnet of 233.242.58.0 that would be globally reserved for AS 62010 to use.

http://www.shepfarm.com/multicast/glop.html

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