IPv4 eBGP through IPv6 iBGP

[lorenzbauer]

 

Hello guys,

I am currently trying to distribute IPv4 BGP Packets through my IPv6 Backend.

I am able form adjancencies between all "needed" Routers, however the Routes don't seem to be forwarded.

Current Configuration:

Left-breakout (A1-POP1)

router bgp 35293
bgp router-id 1.1.1.1
address-family ipv4
neighbor 200.1.4.2 remote-as 7345
neighbor 200.1.4.2 update-source g0/1
neighbor 200.1.4.2 next-hop-self
neighbor 200.1.2.2 remote-as 16360
neighbor 200.1.2.2 update-source g0/2
neighbor 200.1.2.2 next-hop-self
network 200.1.4.0 mask 255.255.255.0
network 200.1.2.0 mask 255.255.255.0

neighbor 2001:cafe::2 remote-as 35293
neighbor 2001:cafe::2 update-source lo1
address-family ipv4
neighbor 2001:cafe::2 activate
address-family ipv6
neighbor 2001:cafe::2 activate
exit
neighbor 2001:cafe::2 next-hop-self

Left-breakout (A1-POP1)

router bgp 35293
bgp router-id 2.2.2.2
address-family ipv4
neighbor 200.1.3.2 remote-as 42196
neighbor 200.1.3.2 update-source g0/0
neighbor 200.1.3.2 next-hop-self
network 200.1.3.0 mask 255.255.255.0

neighbor 2001:cafe::1 remote-as 35293
neighbor 2001:cafe::1 update-source lo1
address-family ipv4
neighbor 2001:cafe::1 activate
address-family ipv6
neighbor 2001:cafe::1 activate
exit
neighbor 2001:cafe::1 next-hop-self




The Routes get forwarded but somehow receive a strange Next-Hop Address (IPv4 instead of IPv6).

sh bgp
BGP table version is 5, local router ID is 1.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
x best-external, a additional-path, c RIB-compressed,
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

Network         Next Hop          Metric    LocPrf Weight Path
* 200.1.2.0    200.1.2.2          0           0         16360    i
*> 0.0.0.0      0 32768 i
* i 200.1.3.0   32.1.202.254     0            100      0              i
* 200.1.4.0.   200.1.4.2          0            0        7345       i
*> 0.0.0.0 0   32768 i
*> 200.2.1.0  200.1.2.2           0           16360               i
* i 200.3.1.0   32.1.202.254     0              100     0           42196 i
*> 200.4.1.0  200.1.4.2 0 7345 i

sh bgp sum

Neighbor           V    AS        MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
2001:CAFE::2    4    35293  30           33           5        0     0       00:21:21  2
200.1.2.2           4    16360  37          38            5       0      0       00:28:42 2
200.1.4.2           4    7345    37          38            5        0     0       00:28:47 2

How do I get these BGP Routes from one Edge-Router to the other? Do I need NAT64? A Route-Map?

A1-POP1#sh ip route | inc B
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
B 200.2.1.0/24 [20/0] via 200.1.2.2, 00:31:45
B 200.4.1.0/24 [20/0] via 200.1.4.2, 00:31:45

I already have a DMVPN Tunnel on IPv6 Basis. Should I give the Tunnel Interface an IPv4 address and set this IP as the next-hop?

Current Configuration on the Left-Breakout(A1-POP1):

interface Tunnel0
description DMVPN_to_other_POPs
no ip address
ipv6 address FE80::1 link-local
ipv6 address 2001:DB8:ABCD:12::1/64
ipv6 nhrp authentication cisco123
ipv6 nhrp map multicast 2001:DB8:AFFE:13::1
ipv6 nhrp map 2001:DB8:ABCD:12::4/64 2001:DB8:AFFE:13::1
ipv6 nhrp network-id 1
ipv6 nhrp nhs 2001:DB8:ABCD:12::4
ipv6 nhrp shortcut
ospfv3 neighbor FE80::4
ospfv3 neighbor FE80::3
ospfv3 neighbor FE80::2
ospfv3 network non-broadcast
ospfv3 200 ipv6 area 0
tunnel source GigabitEthernet0/0
tunnel mode gre multipoint ipv6
tunnel key 1

Thanks in advance,

Lorenz

[Harold Ritter · Accepted solution]

Hi @lorenzbauer ,

The BGP AF IPv4 unicast requires an IPv4 NH. The strange IPv4 NH that you see is actually the first 32 bits of the IPv6 address.

32.1.202.254 = 2001:cafe

You could provide connectivity for you IPv4 traffic over the IPv6 core, but you would need to tunnel your traffic (ipv4 over ipv6 tunnel).

Regards,

[lorenzbauer]

And again, you are right.

I basically just had to tunnel through the Backbone.

int tun0
desc DMVPN_to_other_POPs
no shut

ip add 192.168.0.3 255.255.255.0

tunnel source g0/0
tunnel mode gre multipoint ipv6
tunnel key 1

ip nhrp authentication cisco123
ip nhrp network-id 1
ip nhrp map multicast 2001:DB8:AFFE:13::1
ip nhrp map 192.168.0.4 2001:DB8:AFFE:13::1
ip nhrp nhs 192.168.0.4
ip nhrp shortcut

Thank you very much and I wish you a pleasant day

Lorenz

[Harold Ritter]

You are very welcome @lorenzbauer