BGP ipv6 Implementation

Answered Question
Sep 16th, 2013
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We started to test dual-stack bgp implementation. although we established neighbour over ipv6, seems still we couldnt advertise our networks on internet and we couldnt reach anywhere over ipv6 address.


Here our related configs and outputs;




router bgp 3xxx

no bgp default ipv4-unicast

bgp log-neighbor-changes

neighbor 2A02:E0:0:xx::1 remote-as 34xxx

neighbor x.x.x.x remote-as 34xxx

neighbor x.x.x.x remote-as 91xx

maximum-paths 4

!

address-family ipv4

  .

  .

exit-address-family

!

address-family ipv6

  neighbor 2A02:E0:0:xx::1 activate

  neighbor 2A02:E0:0:xx::1 prefix-list v6in in

  neighbor 2A02:E0:0:xx::1 prefix-list v6out out

  network 2001:67C:xxxx::/48

  no synchronization

exit-address-family

.

.

.

ipv6 prefix-list v6in seq 5 permit ::/0 le 128

!

ipv6 prefix-list v6out seq 5 permit 2001:67C:xxxx::/48

.

.

.

.

.

interface GigabitEthernet0/2

ip address 92.45.xxx.x 255.255.255.252

no ip redirects

no ip proxy-arp

ip flow ingress

load-interval 30

duplex auto

speed auto

media-type rj45

negotiation auto

ipv6 address 2A02:E0:0:xx::2/126

ipv6 enable






7200-1_KULE#sh bgp ipv6 unicast

BGP table version is 4, local router ID is 212.156.xx.xx

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

              r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete



   Network          Next Hop            Metric LocPrf Weight Path

*> ::/0             2A02:E0:0:xx::1                        0 34xx 34xx 130xx 94xx i




What we supposed to do ?


Best regards.

Correct Answer by Harold Ritter about 3 years 10 months ago

Hi,


I see you have a network statement in your BGP configuration. Do you have a matching route installed in your local RIB? This is required to originate the route in BGP. Normally, just a static route to null0 is sufficient.


Regards

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Correct Answer
Harold Ritter Mon, 09/16/2013 - 06:21
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  • Cisco Employee,

Hi,


I see you have a network statement in your BGP configuration. Do you have a matching route installed in your local RIB? This is required to originate the route in BGP. Normally, just a static route to null0 is sufficient.


Regards

CSCO11177789 Mon, 09/16/2013 - 07:04
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Hello;


As you say i add ;


ipv6 route 2001:67C:xxxx::/48 Null0


statement and working now. Thank you


But why we need this ? I'll be very appreciated if  you explain a little.

In ipv4 bgp we dont use similar statements


Best regards

Harold Ritter Mon, 09/16/2013 - 07:13
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  • Cisco Employee,

Hi,


For BGP to originate a route using the network statement, there needs to be a matching route in the RIB. This also applies to ipv4. Of course, you could use a "redistribute statement" instead but the network statement for the aggregate route with a static route to null0 is part of the best practices.


Regards

Harold Ritter Mon, 09/16/2013 - 09:19
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  • Cisco Employee,

Hi,


One more thing. The reason you do not need to have a static route for ipv4 might be that one of the local subnets already matches the network statement you use.


Regards

CSCO11177789 Mon, 09/16/2013 - 13:21
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Yes, we have three  C class networks and one of them is used for firewall side.


May i ask aother question?

On ipv4 bgp conf. we use route maps for coming and outgoing traffic on 3 different metro ethernet internet connections. We have 3 c class ipv4. so we configured load sharing for each networks between net connections. We use local-pref, weight or as path prepend.

Could we do the same thing for ipv6 connections ? We have ::/48 . for example we want to use ::/56 and share networks on internet lines. 


Best regards

Harold Ritter Mon, 09/16/2013 - 19:17
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  • Cisco Employee,

Hi,


The /48 is the longest prefix that ISPs will generally accept. So if you break your /48, it is very unlikely that the longer prefixes will propagate on the Internet. On the other hand, if you do advertise the /48 out to each of your ISPs some load sharing will take place inbound.


Regards

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