Re: IPV6 Tunnels...

From: Narbik Kocharians (narbikk@gmail.com)
Date: Sun Mar 08 2009 - 14:51:07 ARST


Modular,

*There are 5 tunneling solution in IPv6:*

*1. Using the "Tunnel mode ipv6ip", in this case the tunnel source and
destination are configured with IPv4 addressing and the tunnel interface is
configured with IPv6. This will use protocol 41. This is used for IPv6/IPv4.
*

R1(config)#int tunnel 1

R1(config-if)#ipv6 address 12:1:12::1/64

R1(config-if)#tunnel source 10.1.12.1

R1(config-if)#tunnel destination 10.1.12.2

R1(config-if)#*tunnel mode ipv6ip*

*2. Using the "Tunnel mode gre ipv6", in this case the tunnel source and
destination are all configured with IPv6 addressing. This is used for
IPv6/IPv6. *

BB1(config)#int tunnel 1

BB1(config-if)#ipv6 address 121:1:121::111/64

BB1(config-if)#tunnel source 10:1:111::111

BB1(config-if)#tunnel destination 10:1:112::112

BB1(config-if)#*tunnel mode gre ipv6*

*3. In this case, the tunnel mode is NOT used at all, note that the tunnel
interface is configured with IPv6 and the tunnel source and destination is
configured with IPv4 but no mention of tunnel mode. This configuration will
use protocol 47. This is used for IPv6/IPv4. *

R1(config)#int tunnel 13

R1(config-if)#ipv6 address 13:1:13::1/64

R1(config-if)#tunnel source 10.1.13.1

R1(config-if)#tunnel destination 10.1.13.3

*4. Note in this case a special addressing is assigned to the tunnel
interface which is a concatenation of a reserved IPv6 address of
2002followed by the translated
IPv4 address of a given interface on the router. In this configuration ONLY
the tunnel source address is used and since the tunnel is automatic,
the destination
address is NOT configured. The tunnel mode is set to "Tunnel mode ipv6ip
6to4". Note the IPv4 address of 10.1.1.1 is translated to 0A.01.01.01 and
once concatenated, it will be "2002:0A01:0101: or 2002:A01:101. This is used
for IPv6/IPv4.*

R1(config)#interface Tunnel14

R1(config-if)#ipv6 address 2002:A01:101::/128

R1(config-if)#tunnel source 10.1.1.1

R1(config-if)#*tunnel mode ipv6ip 6to4*

*5. ISATAP, ISATAP works like 6to4 tunnels, with one major difference, it
uses a special IPv6 address which is formed as follows: *

*In this tunnel mode, the network portion can be any IPv6 address, whereas,
in 6to4 it had to start with 2002.*

*Note when the IPv6 address is assigned to the tunnel interface, the
"eui-64" is used, in this case the host portion of the IPv6 address starts
with "0000.5EFE" and then the rest of the host portion is the translated
IPv4 address of the tunnel's source IPv4 address. This translation is
performed automatically unlike 6to4. This is used for IPv6/IPv4.*

R4(config)#int tunnel 46

R4(config-if)#ipv6 address 46:1:46::/64 eui-64

R4(config-if)#tunnel source 10.44.44.44

R4(config-if)#*tunnel mode ipv6ip ISATAP*

*A "Show ipv6 int tunnel xx" will reveal the IPv6 address, in this case
10.44.44.44 is used so 10 is translated to "0A" and 44 is translated to
"2C", therefore, your new address should be "46:1:46::5EFE:a2c.2c2c"*
I hope this helped.

On Sun, Mar 8, 2009 at 6:22 AM, Scott Morris <smorris@internetworkexpert.com
> wrote:

> The pro/con I'd look at is overall packet size.
>
> IPv6IP you have a 40-byte IPv6 header + 20-byte IP header
>
> GRE you have a 40-byte IPv6 header + 8 byte GRE header + 20 byte IP header
>
> Which is smaller?
>
> Scott
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> GAURAV MADAN
> Sent: Sunday, March 08, 2009 7:18 AM
> To: Modular
> Cc: Cisco certification
> Subject: Re: IPV6 Tunnels...
>
> No pros / cons as such .. but sometimes language of ques can make us go mad
>
> protocol 47 : GRE
> protocol 41 : IPV6IP
>
> I rememebr these 2 numbers always and can be useful in desiging ACLs as
> well
>
>
> Gaurav Madan.
>
> On Sun, Mar 8, 2009 at 4:37 AM, Modular <modulartx@gmail.com> wrote:
>
> > So I've learned that if you want to tunnel IPv6 over IPv4, there are two
> > easy options you can turn to.
> >
> > 1. Normal GRE tunnel, using the default tunnel type.
> >
> > 2. Configuring ipv6ip tunnel type.
> >
> > What are the pros/cons of using each?
> >
> > Thanks,
> > Mod...
> >
> >
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>

-- 
Narbik Kocharians
CCSI#30832, CCIE# 12410 (R&S, SP, Security)
www.MicronicsTraining.com
www.Net-Workbooks.com
Sr. Technical Instructor

Blogs and organic groups at http://www.ccie.net



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