Re: BGP Address Family

As long as you are looking only for IPv4 unicast neighbors, answer to
your question is yes. The moment you activate neighbor in any other
AF, existing neighbors will be copied to "IP4 unicast".

--
Marko Milivojevic - CCIE #18427
Senior Technical Instructor - IPexpert
FREE CCIE training: http://bit.ly/vLecture
Mailto: markom_at_ipexpert.com
Telephone: +1.810.326.1444
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On Sat, Jun 4, 2011 at 14:29, Bilal Hansrod <bilal.hansrod_at_gmail.com> wrote:
> Thank you very much Marko and Garry,
>
> Is it technically correct to say that standard BGP can be configured without
> using address-family ipv4 unicast? I meant to say that I can do multiple
> configuration of neighbour inside the routing process without needing to use
> address-family ipv4 unicast command.
>
> For example: Configuration under routing process:
>
> router bgp 69
> B no synchronization
> B bgp log-neighbor-changes
> B neighbor 55.55.55.55 remote-as 69
> B neighbor 56.55.55.55 remote-as 69
> B neighbor 57.55.55.55 remote-as 69
> B no auto-summary
>
> Once I create the address family than creation of neighbour under neighbour
> command will automatically activated under address-family as you already
> mentioned.
>
> Thanks once again for your explanation.
>
> Bilal Hansrod
>
>
>
> On Sat, Jun 4, 2011 at 2:48 PM, Marko Milivojevic <markom_at_ipexpert.com>
> wrote:
>>
>> Perfect. Now that we have basics out of the way, we can explore your
>> original questions :-).
>>
>> Disabling "address-family ipv4 unicast" will indeed destroy any
>> configured neighbor sessions in IPv4. See the example:
>>
>> R6 and R9 are interconnected over Se0/2/0 and Se0/2/1:
>>
>> R6 Se0/2/0: 192.168.20.6/24
>> R6 Se0/2/1: 192.168.21.6/24
>> R9 Se0/2/0: 192.168.20.9/24
>> R9 Se0/2/1: 192.168.21.9/24
>>
>> R6:
>> router bgp 69
>> B bgp log-neighbor-changes
>> B neighbor 192.168.20.9 remote-as 69
>> B !
>> B address-family ipv4
>> B neighbor 192.168.20.9 activate
>> B no auto-summary
>> B no synchronization
>> B exit-address-family
>>
>> R9:
>> router bgp 69
>> B bgp log-neighbor-changes
>> B neighbor 192.168.20.6 remote-as 69
>> B !
>> B address-family ipv4
>> B neighbor 192.168.20.6 activate
>> B no auto-summary
>> B no synchronization
>> B exit-address-family
>>
>> If I go to R6 and do this:
>>
>> router bgp 69
>> B no address-family ipv4 unicast
>> !
>>
>> This will be the result:
>>
>> router bgp 69
>> B bgp log-neighbor-changes
>> B neighbor 192.168.20.9 remote-as 69
>> B !
>> B address-family ipv4
>> B no neighbor 192.168.20.9 activate
>> B no auto-summary
>> B no synchronization
>> B exit-address-family
>>
>> However, when I create new neighbor statement OUTSIDE the
>> address-family, we'll see that neighbor will automatically be
>> activated in IPv4 unicast address-family:
>>
>> R6(config)#router bgp 69
>> R6(config-router)# neighbor 192.168.21.9 remote-as 69
>> R6(config-router)#do sh run | s router bgp
>> router bgp 69
>> B bgp log-neighbor-changes
>> B neighbor 192.168.20.9 remote-as 69
>> B neighbor 192.168.21.9 remote-as 69
>> B !
>> B address-family ipv4
>> B no neighbor 192.168.20.9 activate
>> B neighbor 192.168.21.9 activate
>> B no auto-summary
>> B no synchronization
>> B exit-address-family
>>
>> Now, if I wanted to disable this automatic creation of IPv4 unicast
>> neighbors whenever I created a neighbor, I would run a command "no bgp
>> default ipv4-unicast". Then, when I add the neighbor it won't
>> automatically get created. Also, I will be able to remove IPv4
>> address-family (which I was not able to do in this case, but it would
>> have worked if I had session active in another AF - just to make
>> things more complicated to explain the exact behavior to us
>> instructors). See:
>>
>> R6(config)#router bgp 69
>> R6(config-router)#no bgp default ipv4-unicast
>> R6(config-router)#no address-family ipv4
>> R6(config-router)#do sh run | s router bgp
>> router bgp 69
>> B no bgp default ipv4-unicast
>> B bgp log-neighbor-changes
>> B neighbor 192.168.20.9 remote-as 69
>> B neighbor 192.168.21.9 remote-as 69
>>
>> I hope this cleared out the purpose of "no bgp default ipv4-unicast"
>> and how it's different from the actual "address-family ipv4 unicast".
>>
>> --
>> Marko Milivojevic - CCIE #18427
>> Senior Technical Instructor - IPexpert
>>
>> FREE CCIE training: http://bit.ly/vLecture
>>
>> Mailto: markom_at_ipexpert.com
>> Telephone: +1.810.326.1444
>> Web: http://www.ipexpert.com/
>>
>> On Fri, Jun 3, 2011 at 19:35, Bilal Hansrod <bilal.hansrod_at_gmail.com>
>> wrote:
>> > Thanks Marc,
>> >
>> > I believe, there are three options with this command (address-family
>> > ipv4
>> > unicast). i.e.
>> >
>> > *address-family ipv4* [*multicast* | *unicast* | *vrf* *vrf-name*]
>> >
>> > If I am only using address-family ipv4 unicast that I am not referencing
>> > to
>> > vrf and essence not using vrf. By researching more and reading this Blog
>> > (
>> >
>> > http://blog.ioshints.info/2008/06/use-explicit-address-family-ipv4-in-bgp.html),
>> > I understand it provides easy to read configuration feature if we are
>> > using
>> > all three options such as MPLS VPN, IPv6 or IP Multicast over BGP.
>> >
>> > Thanks,
>> >
>> >
>> > Bilal Hansrod
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> > B Sat, Jun 4, 2011 at 12:15 PM, marc edwards <renorider_at_gmail.com> wrote:
>> >
>> >> Will add 32 bits to header to carry vrf information over MPLS backbone.
>> >> Essentially that command enables MP BGP
>> >> On Jun 3, 2011 6:46 AM, "Bilal Hansrod" <bilal.hansrod_at_gmail.com>
>> >> wrote:
>> >> > Hello Team,
>> >> >
>> >> > I was working on BGP lab and came across multiple address family
>> >> > command.
>> >> > Can anyone please explain one of the below command and correct other
>> >> > two
>> >> if
>> >> > it is incorrect.
>> >> >
>> >> > 1. address-family ipv4 unicast - I have disabled this command instead
>> >> > of
>> >> > disabling no bgp default ipv4-unicast. I didn't see any difference,
>> >> > may
>> >> be I
>> >> > don't know why we need this command.
>> >> >
>> >> > 2. no bgp default ipv4-unicast - This command is required to disable
>> >> normal
>> >> > IPv4 adjacency.
>> >> >
>> >> > 3. address-family vpnv4 unicast - This command will provide mechanism
>> >> > to
>> >> > carry additional attributes across BGP updates such as RT,SoO,
>> >> > Domain-ID,
>> >> > metric propagation and make true MP-BGP.
>> >> >
>> >> > I have seen some past post, but still little bit confused.
>> >> >
>> >> > Can anyone please shed some light on above points.
>> >> >
>> >> > Thanks,
>> >> >
>> >> > Bilal Hansrod
>> >> >
>> >> >
>> >> > Blogs and organic groups at http://www.ccie.net
>> >> >
>> >> >
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