400-007 · Question #124
The network designer needs to use GLOP IP addresses in order to make them unique within their ASN. Which multicast address range should be used?
The correct answer is B. H233.0.0 0 to 233.255.255 255. GLOP addressing (RFC 3180) reserves the 233.0.0.0/8 multicast range, encoding the 16-bit ASN into octets 2 and 3 to provide globally unique multicast addresses per autonomous system.
Question
The network designer needs to use GLOP IP addresses in order to make them unique within their ASN. Which multicast address range should be used?
Options
- A232.0.0.0 to 232 255.255.255
- BH233.0.0 0 to 233.255.255 255
- C239000 to 239255255.255
- D224000 to 2240.0 255
How the community answered
(43 responses)- A2% (1)
- B88% (38)
- C5% (2)
- D5% (2)
Why each option
GLOP addressing (RFC 3180) reserves the 233.0.0.0/8 multicast range, encoding the 16-bit ASN into octets 2 and 3 to provide globally unique multicast addresses per autonomous system.
232.0.0.0/8 is the Source-Specific Multicast (SSM) range defined in RFC 4607, reserved for SSM applications - not GLOP.
The GLOP range 233.0.0.0 to 233.255.255.255 is defined in RFC 3180; it maps a 16-bit ASN into the second and third octets of the address, giving each AS 256 unique globally unambiguous multicast addresses that require no coordination with other organizations.
239.0.0.0/8 is the Administratively Scoped multicast address range reserved for private and internal use per RFC 2365, not GLOP addressing.
224.0.0.0/24 and the broader 224.0.0.0 block contain well-known link-local reserved multicast addresses assigned by IANA, not the GLOP range.
Concept tested: GLOP multicast address range per RFC 3180
Source: https://www.rfc-editor.org/rfc/rfc3180
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