[nsp] ipv6 address ::X/128 on Cisco router

[Yinglam Cheung]

my intention is to know a little about why vendor C doesn't like it but vendor J has no issue. calling this as "nonsense" address is mostly not a convincing answer. However, "implementation dependent" seems to be more acceptable. Personally I tend to favor J vendor's implementation. (Another issue from vendor C's implementation is that it actually takes such prefix in its routing table and happily advertise too).
 
I'm not asking if this is a global address or whatsoever..
 
According to RFC 3513 (ipv6 addressing architecture):

The initial assignment of IPv6 address space is as follows:

   Allocation                            Prefix         Fraction of
                                         (binary)       Address Space
   -----------------------------------   --------       -------------
   Unassigned (see Note 1 below)         0000 0000      1/256
Notes:

   1. The "unspecified address", the "loopback address", and the IPv6
      Addresses with Embedded IPv4 Addresses are assigned out of the
      0000 0000 binary prefix space.


Since an address like ::7/128 is not defined as reserved, why it cannot be used? Maybe someone should revise rfc to call ::x/128 as nonsense address block.
 

Mohacsi Janos <mohacsi at niif.hu> wrote:



On Thu, 17 Jun 2004, Yinglam Cheung wrote:

> Hi,
>
> it seems that I cannot use any /128 ipv6 address on Cat6509. it's understood that :: and ::1 are reserved, but I'm not sure the others in /128. The cat6509 is running s720 with 12.2(17d)SXB.
>
> s720(config-if)#int lo0
> s720(config-if)#ipv addr ::7/128
> % Invalid address
>

Try using global addresses instead of nonsense addresses... ::7/128 is not
valid either link local or global usage. We are using /128 on loopback
addresses with global addressses on C65xx and it works ok.
Regards,

Janos Mohacsi
Network Engineer, Research Associate
NIIF/HUNGARNET, HUNGARY
Key 00F9AF98: 8645 1312 D249 471B DBAE 21A2 9F52 0D1F 00F9 AF98



> however, I can assign ::5/128 to a juniper router and actually I advertise this route to Cat6509:
> s720#sh ipv ro ospf
> IPv6 Routing Table - 10 entries
> Codes: C - Connected, L - Local, S - Static, R - RIP, B - BGP
> I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary
> O - OSPF intra, OI - OSPF inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2
> O ::5/128 [110/1]
> via FE80::290:69FF:FE98:3001, FastEthernet2/3
> s720# ping ipv ::5
> Type escape sequence to abort.
> Sending 5, 100-byte ICMP Echos to ::5, timeout is 2 seconds:
> !!!!!
> Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms
>
>
>
>
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