MP-BGP for IPv6

I recently passed the CCNP SWITCH exam, so now Spanning-tree is out the window, and I am firmly concentrated on all things layer 3 in preparation for the CCNP ROUTE exam.

One of the areas I have not really had much exposure too is IPv6.  So I have spent the last few days going over the theory behind it, and trying to put it into practice.

Below is the topology i have been using for MP-BGP (MultiProtocol BGP)

I have used /127 addresses for the links between the routers, and R1 and R3 have loopback interfaces to simulate host networks.

Again, I am new to IPv6 so any feedback on design etc.. is welcome!! I’m assuming that anyone reading this has some experience of BGP in IPv4 networks, so i;m not going into massive depth on the config as mostly its the same, just different 😀

First step is to configure the IPv6 addresses on the interfaces;

R1
interface FastEthernet0/0
 ipv6 address 2001:1::/127

R2
interface FastEthernet0/0
 ipv6 address 2001:1::1/127
interface FastEthernet0/1
 ipv6 address 2001:2::/127

R3
interface FastEthernet0/1
 ipv6 address 2001:2::1/127

Next, enable IPv6 routing globally with the “ipv6 unicast-routing” command. Now to configure the loopback interfaces

R1 user 2001:11:: and R3 uses 2001:10::

interface Loopback0
 ipv6 address 2001:11::1/112
interface Loopback1
 ipv6 address 2001:11::1:1/112
interface Loopback2
 ipv6 address 2001:11::2:1/112
interface Loopback3
 ipv6 address 2001:11::3:1/112
interface Loopback4
 ipv6 address 2001:11::4:1/112

There are several stages to configuring MP-BGP, first is to enable BGP and disable IPv4. Unlike OSPFv3 you configure MP-BGP under the same process as standard BGP

router bgp 1545
 bgp router-id 1.1.1.1
 no bgp default ipv4-unicast

Now, add your peer’s IPv6 address and the remote ASN

 neighbor 2001:1::1 remote-as 8547

You now need to create an IPv6 address family, and add the neighbor to it

 address-family ipv6
  neighbor 2001:1::1 activate

Any other BGP commands you might want to use are carried out within the address-family – network, aggregate-address, additional neighbor commands. So in order to advertise the loopback interfaces;

 address-family ipv6
  network 2001:11::0:1/112
  network 2001:11::1:1/112
  network 2001:11::2:1/112
  network 2001:11::3:1/112
  network 2001:11::4:1/112

and if we want to create a summary range

 address-family ipv6
  aggregate-address 2001:11::/96 summary-only

The full BGP configs for all 3 routers are as follows

R1

router bgp 1545
 bgp router-id 1.1.1.1
 no bgp default ipv4-unicast
 bgp log-neighbor-changes
 neighbor 2001:1::1 remote-as 8547
 !
 address-family ipv6
  neighbor 2001:1::1 activate
  network 2001:11::0:1/112
  network 2001:11::1:1/112
  network 2001:11::2:1/112
  network 2001:11::3:1/112
  network 2001:11::4:1/112
  aggregate-address 2001:11::/96 summary-only
  no synchronization
 exit-address-family

R2

router bgp 8547
 bgp router-id 2.2.2.2
 no bgp default ipv4-unicast
 bgp log-neighbor-changes
 neighbor 2001:1:: remote-as 1545
 neighbor 2001:2::1 remote-as 8547
 !
 address-family ipv6
  neighbor 2001:1:: activate
  neighbor 2001:2::1 activate
  neighbor 2001:2::1 next-hop-self
 exit-address-family

R3

router bgp 8547
 bgp router-id 3.3.3.3
 no bgp default ipv4-unicast
 bgp log-neighbor-changes
 neighbor 2001:2:: remote-as 8547
 !
 address-family ipv6
  neighbor 2001:2:: activate
  neighbor 2001:2:: next-hop-self
network 2001:10::0:1/112
network 2001:10::1:1/112

  network 2001:10::2:1/112
  network 2001:10::3:1/112
  network 2001:10::4:1/112
  aggregate-address 2001:10::/96 summary-only
 exit-address-family

The show commands have also changed slightly, some examples are;

  • show ip bgp > show ip bgp ipv6 unicast
  • show ip bgp summary > show ip bgp ipv6 unicast summary

Hopefully this is all good, again, i cant stress enough, I’m a novice in terms of IPv6, so please feel free to comment with suggestions and improvements.

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