NCNU VoIP Mid-Term

Date: May 21st, 2007
Time: 14:10-17:00

1. Explain why we do not need the field of Internet Header Length in an IPv6 header.
2. Point out the incorrect addresses in Figure 2-24 and correct them.
3. For an IPv6-in-IPv4 tunneled packet, what is the (decimal) value of the Protocol field in IPv4 header?
4. What is the link-local all-router multicast IPv6 address?
5. Briefly describe what changes are introduced by the mechanism of IPv6 Node Information Queries (RFC4620), and describe some scenario which may need this mechanism.
6. Explain why RFC 4835 (Cryptographic Algorithm Implementation Requirements for Encapsulating Security Payload and Authentication Header) wants to update RFC 2402 and deprecates some cryptographic algorithms.
7. Describe the range of IPv4/IPv6 addresses that are designated to multicast destination addresses.  
8. Describe the range of IPv4/IPv6 addresses that are designated to source-specific multicast destination addresses.
9. Describe a scenario where ISATAP is useful while 6to4 is not applicable.
10. Describe why IPv4 and IPv6 Dual-Stack mechanism may cause some issues to Dynamic Host Configuration Protocol (DHCP).
    

1. IPv6 header length is fixed (40Bytes).
2. • src=3ffe:b00:a:1::1
   • IPv6=3ffe:b00:a:1::1
   • router IPv6=3ffe:b00:a:1::2
3. 41
4. FF02::2
5. RFC 4620
6. RFC 4835
7. IPv4: 224.0.0.0 - 239.255.255.255 (RFC 1112)
   IPv6: FF00::/8 (RFC 3513)
8. IPv4: 232/8 (232.0.0.0 - 232.255.255.255)
   IPv6: FF3x::/32 (RFC 4607)
9. When the node has a private IPv4 address.
10. Because the IPv4 DHCP server may be inconsistent with IPv6 DHCP server.