IPv6 urgent help

Unanswered Question
Jan 2nd, 2009

guys today i came across a wierd exercise......there are two router connected togather via FR line....now the address to be config is 4588:jhg:tre::/64 and it shd be in eui-64 format.....now remaining part of the ipv6 subnet shd be taken from the third octat of the serial interface.....now the problem is both router s on are same address now i am confuse abt both routers serial address third octact is 1 so it means that the ipv6 address will look like

4588:jhg:tre:1::/64 eui-64 am i doing wrong or its something with ipv6....as how come both interface on serial which is connected via FR will have same ip address guys can someone help me abt this whats the right way to do it.....thanks guys

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Giuseppe Larosa Fri, 01/02/2009 - 03:10

Hello Khan,

the request is correct:

to talk in ipv6 the two addresses must be in the same ipv6 subnet.

By using eui-64 you need to specify only the net portion of the /64 address and this must be the same on both endpoints.

the last 64 bits (ipv6 addresses are 128 bits wide) are taken by using a MAC address of a LAN interface (48 bits) with some transformations on the router

Rather how can you use jhg and so on if the only allowed digits are 0-9a-f ?

I guess you have masked the digits ignore above question

Hope to help


The_guroo_2 Fri, 01/02/2009 - 06:05

sorry but didnt get it.....can you explain a bit in easy language sorry abt that

Giuseppe Larosa Fri, 01/02/2009 - 06:38

Hello Khan,

Sorry if I've been unclear

IPv6 address: 128 bits long

IPv6 eui-64: 64 bits of network part, 64 bits of host part

host part: 64 bits derived from a MAC address on the router with some changes

network part: it is 64 bits and has to be the same so the original request in your exercise is correct because they ask you to set part of the network section not the host portion so it is necessary to use the same value on both routers or they will be in two different /64 IPv6 subnets



Hope to help


The_guroo_2 Fri, 01/02/2009 - 08:28

thnaks for your help now ip address looks like this on both routers

router A 4588:jhg:tre:1::/64 eui-64

router B 4588:jhg:tre:1::/64 eui-64

as the ipv4 address between them thrid octact is 1 .....now i config that on both end cant ping it why is thaT


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