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IPv4 Vs IPv6


Hello folks,

Looking for further assistance in reards to IPv4 & 6.

Got two PCs one is a dell running IPv4 and the other is a Sony running IPv6.

I tried to connect the two PCs using an ethernet cross-over cable.

LEds by the ports showed green meaning that there was physical connectivity.

However, in configuring the IP addresses and assiging them to the same subnet, I coul still not get connectivity. Assuming that all other possibilities were configured correctly, does the IP version matter when transfering files?

when i configured static addresses & did an ipconfig on both PCs,

the sony came up with a 128 bit Hexadecimal address as the address while the dell came up with the normal IPv4 32 bit address.

Please advis if this would cause an issue and if so the best way to tackle it.

Also in IPv6 addresses on a local link are autoconfigured thus devices on the same local link will have the FE80::/10 prefix. Does any one know how this numbering comes about?

Also global unicast addresses have the first 48 bits used by the IANA and the next 16 bits to identify the SLA which leaves 64 bits to the interface which is configured with the device's MAC Address.

Am I corect in saying that MAC addresses will always be 6 byts in length? and if so what happens to the remaining 16 bits in the IPv6 adressing scheme when the MAC address is autoconfigured (which uses up only 48 bits).

Many Thanks


Many Thanks


1 Reply 1

Harold Ritter
Cisco Employee
Cisco Employee

The two PCs need a common protocol in order to communicate. They will not be able to do so if one runs IPv4 and the other one v6. You could run a dual stack (v4 and v6) on one of them to solve the issue.

Hope this helps,

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
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Cuauhtémoc, Juárez
Ciudad de México, 06600
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