OVERVIEW
By definition GRE is used to encapsulate IP/non-IP protocols into IPv4/IPv6, in the following lab we will transport IPv6 into IPv4, so the outer packet has IPv4/6 source and destination addresses and the inner packet GRE, has IPv6 source and destination addresses (figure 1).
Figure 1: Packet encapsulation
Figure 2 depicts the lab topology in which 3 sites: North, East, and West are isolated IPv6 sites and connected with each other over an IPv4 network with their respective border routers (support both IPv4 and IPv6).
Each site establish a FR point-to-point PVC to the other two with IPv4 as the network layer.
Figure 2: Topology
This document is organized as follow:
- Planning the address scheme.
- IPv6 address configuration.
- IPv6 connectivity check.
- FR configuration.
- FR connectivity check.
- Manual IPv6 GRE tunnel
-tunnel configuration
- Connectivity check.
PLANNING THE ADDRESS SCHEME
Table 1:Addressing scheme:
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2001:a:a:a::/64
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Subnet used between BNorth and Northv6
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2001:a:a:aa::64
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North site Internal network
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2001:b:b:b::/64
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Subnet used between BWest and Westv6
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2001:b:b:bb::/64
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Worth site Internal network
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2001:c:c:c::/64
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Subnet used between BEast and Eastv6
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2001:c:c:cc/64
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East site Internal network
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Tunnel’s IPv6 addressing
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2001a:a:ab::/64
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Tunnel between BNorth and BWest
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2001:a:a:ac::/64
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Tunnel between BNorth and Beast
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2001:a:a:bc::/64
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Tunnel between BWest and BEast
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IPv4 NBMA addressing
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192.168.13.0/24
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NBMA subnet for point-to-point PVC between BNorth and BWest
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192.168.32.0/24
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NBMA subnet for point-to-point PVC between BEast and BWest
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192.168.12.0/24
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NBMA subnet for point-to-point PVC between BNorth and BEst
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IPv6 ADDRESS CONFIGURATION
North Site:
Northv6:
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!! Do not forget to enable IPv6 routing
ipv6 unicast-routing ! !! loopback is used to simulate internal networks
!! interface Loopback0
ipv6 address 2001:A:A:AA::1/64 ! !! Interface that connect to the Border router
!! interface FastEthernet0/0
ipv6 address 2001:A:A:A::2/64 ! !! A default route will point to the next-hop (Border Router)
ipv6 route ::/0 2001:A:A:A::1 |
BNorth:
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ipv6 unicast-routing ! interface FastEthernet0/0 ipv6 address 2001:A:A:A::1/64 !! This a route to the internal network that points the internal router
ipv6 route 2001:A:A:AA::/64 2001:A:A:A::2 |
East Site:
Eastv6:
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ipv6 unicast-routing ! interface Loopback0 ipv6 address 2001:C:C:CC::1/64 ! interface FastEthernet1/0 ipv6 address 2001:C:C:C::2/64 ! ipv6 route ::/0 2001:C:C:C::1 |
BEast:
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ipv6 unicast-routing ! interface FastEthernet0/0 ipv6 address 2001:C:C:C::1/64 ! ipv6 route 2001:C:C:CC::/64 2001:C:C:C::2 |
West Site:
Westv6:
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ipv6 unicast-routing ! interface Loopback0 ipv6 address 2001:B:B:BB::1/64 ! interface FastEthernet0/0 ipv6 address 2001:B:B:B::2/64 ! ipv6 route ::/0 2001:B:B:B::1 |
BWest:
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ipv6 unicast-routing ! interface FastEthernet0/0 ipv6 address 2001:B:B:B::1/64 ! ipv6 route 2001:B:B:BB::/64 2001:B:B:B::2 |
IPv6 connectivity
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BNorth(config)#do ping 2001:a:a:aa::1
Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 2001:A:A:AA::1, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 36/56/92 ms BNorth(config)# |
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BEast(config)#do ping 2001:c:c:cc::1
Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 2001:C:C:CC::1, timeout is 2 seconds: !!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 20/38/88 ms BEast(config)# |
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BWest(config)#do ping 2001:b:b:bb::1
Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 2001:B:B:BB::1, timeout is 2 seconds: !!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 8/43/96 ms BWest(config)# |
FR CONFIGURATION
The configuration for point-to-point FR is very simple, configure the ip address and the local DLCI, no need for neither inverse ARP nor static mapping as there is only one DLCI in the other side of the PVC.
BNorth:
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interface Serial1/0 no ip address encapsulation frame-relay no frame-relay inverse-arp ! interface Serial1/0.101 point-to-point ip address 192.168.12.1 255.255.255.0 frame-relay interface-dlci 101 ! interface Serial1/0.102 point-to-point ip address 192.168.13.1 255.255.255.0 frame-relay interface-dlci 102 |
BEst:
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interface Serial1/0 no ip address encapsulation frame-relay no frame-relay inverse-arp ! interface Serial1/0.110 point-to-point ip address 192.168.12.2 255.255.255.0 frame-relay interface-dlci 110 ! interface Serial1/0.203 point-to-point ip address 192.168.32.1 255.255.255.0 frame-relay interface-dlci 203 |
BWest:
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interface Serial1/0 no ip address encapsulation frame-relay no frame-relay inverse-arp ! interface Serial1/0.201 point-to-point ip address 192.168.13.2 255.255.255.0 frame-relay interface-dlci 201 ! interface Serial1/0.302 point-to-point ip address 192.168.32.2 255.255.255.0 frame-relay interface-dlci 302 |
FR connectivity check
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BWest#ping 192.168.13.1
Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 192.168.13.1, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 24/80/108 ms BWest# BWest#ping 192.168.32.1
Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 192.168.32.1, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 40/72/120 ms BWest# |
IPv6 GRE
It is a point-to-point tunnel, so the tunnel source and destination are preconfigured, the logical topology is illustrated in figure3.
Figure3: Logical topology
Table2: Point-to-point GRE parameters on BNorth
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Tunnelling parameters
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BEast
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BWest
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Tunnel interface
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Tunnel 12
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Tunnel 13
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Tunnel ip address &mask
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2001:a:a:ac::1/64
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2001:a:a:ab::1/64
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Tunnel source interface
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s0/0.101
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s0/0.102
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Tunnel destination
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192.168.12.2
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192.168.13.2
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Tunnel mode
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Ipv6ip
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BNorth:
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interface Tunnel12 no ip address ipv6 address 2001:A:A:AC::1/64 tunnel source Serial1/0.101 tunnel destination 192.168.12.2 tunnel mode ipv6ip ! interface Tunnel13 no ip address ipv6 address 2001:A:A:AB::1/64 tunnel source Serial1/0.102 tunnel destination 192.168.13.2 tunnel mode ipv6ip ! !!Each Border router will be configured with static routes to other sites !!internal networks
ipv6 route 2001:B::/32 Tunnel13 ipv6 route 2001:C::/32 Tunnel12
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BEst:
Table2: Point-to-point GRE parameters on BEast
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Tunnelling parameters
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BNorth
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BWest
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Tunnel interface
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Tunnel 21
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Tunnel 23
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Tunnel ip address &mask
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2001:a:a:ac::2/64
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2001:a:a:bc::1/64
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Tunnel source interface
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s0/0.110
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s0/0.203
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Tunnel destination
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192.168.12.1
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192.168.32.1
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Tunnel mode
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Ipv6ip
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interface Tunnel21 no ip address ipv6 address 2001:A:A:AC::2/64 tunnel source Serial1/0.110 tunnel destination 192.168.12.1 tunnel mode ipv6ip ! interface Tunnel23 no ip address ipv6 address 2001:A:A:BC::1/64 tunnel source Serial1/0.203 tunnel destination 192.168.32.2 tunnel mode ipv6ip ! ipv6 route 2001:A::/32 Tunnel21 ipv6 route 2001:B::/32 Tunnel23
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BWest:
Table2: Point-to-point GRE parameters on BWest
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Tunnelling parameters
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BEast
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BNorth
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Tunnel interface
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Tunnel 32
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Tunnel 31
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Tunnel ip address &mask
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2001:a:a:bc::2/64
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2001:a:a:ab::2/64
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Tunnel source interface
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s0/0.302
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s0/0.201
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Tunnel destination
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192.168.32.2
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192.168.13.1
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Tunnel mode
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Ipv6ip
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interface Tunnel31 no ip address ipv6 address 2001:A:A:AB::2/64 tunnel source Serial1/0.201 tunnel destination 192.168.13.1 tunnel mode ipv6ip ! interface Tunnel32 no ip address ipv6 address 2001:A:A:BC::2/64 tunnel source Serial1/0.302 tunnel destination 192.168.32.1 tunnel mode ipv6ip ! ipv6 route 2001:A::/32 Tunnel31 ipv6 route 2001:C::/32 Tunnel32 |
CONNECTIVITY CHECK
For each destination site IPv6 packets take the corresponding tunnel and encapsulated into a packet with that tunnel source and destination.
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Northv6#trace 2001:c:c:cc::1
Type escape sequence to abort. Tracing the route to 2001:C:C:CC::1
1 2001:A:A:A::1 36 msec 32 msec 48 msec 2 2001:A:A:AC::2 132 msec 72 msec 100 msec 3 2001:C:C:CC::1 148 msec 196 msec 120 msec Northv6#trace 2001:b:b:bb::1
Type escape sequence to abort. Tracing the route to 2001:B:B:BB::1
1 2001:A:A:A::1 40 msec 36 msec 12 msec 2 2001:A:A:AB::2 136 msec 136 msec 44 msec 3 2001:B:B:BB::1 136 msec 68 msec 188 msec Northv6#
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DEBUGGING:
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BNorth(config)#
*Mar 1 05:41:36.790: Tunnel13: IPv6/IP encapsulated 192.168.13.1->192.168.13.2 (linktype=79, len=120)
*Mar 1 05:41:36.914: Tunnel13: IPv6/IP to classify 192.168.13.2->192.168.13.1 (len=120 ttl=254 tos=0×0)
*Mar 1 05:41:36.918: Tunnel13: to decaps IPv6/IP packet 192.168.13.2->192.168.13.1 (len=120, ttl=254)
*Mar 1 05:41:36.922: Tunnel13: decapsulated IPv6/IP packet
*Mar 1 05:41:36.926: 2001:B:B:BB::1 -> 2001:A:A:A::2 (len=60 ttl=63)
BNorth(config)#
BNorth(config)#
BNorth(config)#
*Mar 1 05:42:03.730: Tunnel12: IPv6/IP encapsulated 192.168.12.1->192.168.12.2 (linktype=79, len=120)
*Mar 1 05:42:03.850: Tunnel12: IPv6/IP to classify 192.168.12.2->192.168.12.1 (len=120 ttl=254 tos=0×0)
*Mar 1 05:42:03.858: Tunnel12: to decaps IPv6/IP packet 192.168.12.2->192.168.12.1 (len=120, ttl=254)
*Mar 1 05:42:03.858: Tunnel12: decapsulated IPv6/IP packet
*Mar 1 05:42:03.862: 2001:C:C:CC::1 -> 2001:A:A:A::2 (len=60 ttl=63)
BNorth(config)#
BNorth(config)#
BNorth(config)#do un all
All possible debugging has been turned off
BNorth(config)#
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