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New Member

IPV6 SUMMARISATION

Hello All,

Could someone please help me to demystify how an author came about getting answer to the following summarisation as 2000:444:444:4440::/64 ?

2000:444:444:4440::444/64

2000:444:444:4441::444/64

2000:444:444:4442::444/64

2000:444:444:4443::444/64

If the first three WORD (not octet since it's 16bits) will give us 48bit, the fouth WORD, where the summary took place had the first three session on (to me which mean 12 bits) if added to the initial 48bits i believed should be /60, but how come the author had /62 or was it a mistake from him?

Please help,

Kind Regards

2 REPLIES
Cisco Employee

Re: IPV6 SUMMARISATION

If you meant the summarized prefix is 2000:444:444:4440::/62 then the author is right.

If you look at the 4th block of 16 bits, it is not the first 12 bits that are identical for the 4 prefixes but rather the first 14 bits, which would lead to a /62 summary.

4440 = 0x0100010001000000

4441 = 0x0100010001000001

4442 = 0x0100010001000010

4443 = 0x0100010001000011

Regards

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México 
Paseo de la Reforma 222 Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
New Member

Re: IPV6 SUMMARISATION

Hritter,

Many thanks for your brilliant explanation that has brought summarsing IPv6 to life for me.

Most grateful for your time.

Regards

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