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1647 Views 2 Replies Latest reply: Jan 4, 2012 5:05 AM by Erick RSS

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Ethernet Frame format for IPv6 stack? SA & DA are 48bits but IPv6 address is 128 bits long?

Jan 4, 2012 4:03 AM

Deepak Ambotkar- CCIE,JNCIA 47 posts since
Mar 30, 2010

Hello Champs,

 

I am trying to enable DHCP in our LAN. The path from access devices till DHCP server (router) has 2 switches in between. So I was going through the ethernet frame format to decide if I will need to enable IPv6 only on the end station & DHCP or the complete path.  ( I will set this in lab soon)

 

Multiple questions (sorry if any stupid) :-

 

1) Is it necessary to enable IPv6 stack on each & every device in the path including switches? ( I guess Ethertype for IPv4 was set to 0x0800 & IPv6 has 0x86DD so every device in the path should be able to process IPv6 frame, so we will need to enable IPv6 on each device in the path)

 

2) How will the Source & destination MAC are mapped for IPv6 address? (For IPv4 32 bit IP we had broadcast of all FF's to find the destination. So IPv4 was only 32bit & mapped easily in 48bit MAC. But for IPv6 is 128 bits longer & how will it be mapped with 48bit MAC?)

 

I am clear about solicited node multicast, FF02::1 stuff to find dest MAC when IP is known.

 

3) Also I would like to know what happens in the background when suppose 2 routers connected on the same switch with OSPF enabled & what is the structure of the L2 ethernet frame to detect that OSPF enabled routers are connected on the specific port with either OSPF or OSPFv3. Also can you suggest debug commands so that I will build up same setup in the lab with 1 switch,2 routers with OSPF & OSPFv3 enabled and screen whats happening in the background?

 

 

 

Please help.

 

Thanks in advance,

Deepak

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