Re: Difference between tunnel modes: GRE/IP versus IPv6/IP

' difference in functionality ' that i can see from a quick debug ip packet
is

GRE/IP = len 124, sending, proto=47
 IPv6/IP = len 120, sending, proto=41

changing the way the tunnel is encapusaled, in size at least....

Tunnel1 is up, line protocol is up
  Hardware is Tunnel
  MTU 1514 bytes, BW 9 Kbit/sec, DLY 500000 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation TUNNEL, loopback not set
  Keepalive not set
  Tunnel source 1.1.1.12, destination 1.1.1.11
  Tunnel protocol/transport GRE/IP

R11#ping 3001::12 r 1
Type escape sequence to abort.
Sending 1, 100-byte ICMP Echos to 3001::12, timeout is 2 seconds:
!
Success rate is 100 percent (1/1), round-trip min/avg/max = 80/80/80 ms

R12#
IP: s=1.1.1.12 (Tunnel1), d=1.1.1.11 (FastEthernet0/0), len 124, sending,
proto=47

R12#sh int tunnel 1
Tunnel1 is up, line protocol is up
  Hardware is Tunnel
  MTU 1514 bytes, BW 9 Kbit/sec, DLY 500000 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation TUNNEL, loopback not set
  Keepalive not set
  Tunnel source 1.1.1.12, destination 1.1.1.11
  Tunnel protocol/transport IPv6/IP

R11#ping 3001::12 r 1
Type escape sequence to abort.
Sending 1, 100-byte ICMP Echos to 3001::12, timeout is 2 seconds:
!
Success rate is 100 percent (1/1), round-trip min/avg/max = 68/68/68 ms

R12#
IP: tableid=0, s=1.1.1.11 (FastEthernet0/0), d=1.1.1.12 (FastEthernet0/0),
routed via RIB
IP: s=1.1.1.11 (FastEthernet0/0), d=1.1.1.12 (FastEthernet0/0), len 120,
rcvd 3, proto=41
IP: s=1.1.1.12 (Tunnel1), d=1.1.1.11 (FastEthernet0/0), len 120, sending,
proto=41

--
Garry L. Baker
"There is no 'patch' for stupidity." - www.sqlsecurity.com
On Tue, Feb 23, 2010 at 12:47 PM, Andy Reid <ccie_at_reid.it> wrote:
> Hi All,
>
> Could someone explain to me the difference between GRE/IP and IPv6/IP
> tunnel modes when the GRE/IP tunnel has an IPv6 address configured at each
> end.
>
> Both tunnel modes have an IPv4 source and destination address. The only
> difference I can spot is in the "show int tunnel x" command where the Tunnel
> protocol/transport is shown differently. I can't spot any difference in
> functionality at the moment.
>
> regards Andy
>
>
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