Re: BGP Address Family

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
 no synchronization
 bgp log-neighbor-changes
 neighbor 55.55.55.55 remote-as 69
 neighbor 56.55.55.55 remote-as 69
 neighbor 57.55.55.55 remote-as 69
 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 <http://192.168.20.9/24%0AR9> Se0/2/1: 192.168.21.9/24
>
> R6:
> router bgp 69
> bgp log-neighbor-changes
> neighbor 192.168.20.9 remote-as 69
> !
> address-family ipv4
> neighbor 192.168.20.9 activate
> no auto-summary
> no synchronization
> exit-address-family
>
> R9:
> router bgp 69
> bgp log-neighbor-changes
> neighbor 192.168.20.6 remote-as 69
> !
> address-family ipv4
> neighbor 192.168.20.6 activate
> no auto-summary
> no synchronization
> exit-address-family
>
> If I go to R6 and do this:
>
> router bgp 69
> no address-family ipv4 unicast
> !
>
> This will be the result:
>
> router bgp 69
> bgp log-neighbor-changes
> neighbor 192.168.20.9 remote-as 69
> !
> address-family ipv4
> no neighbor 192.168.20.9 activate
> no auto-summary
> no synchronization
> 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
> bgp log-neighbor-changes
> neighbor 192.168.20.9 remote-as 69
> neighbor 192.168.21.9 remote-as 69
> !
> address-family ipv4
> no neighbor 192.168.20.9 activate
> neighbor 192.168.21.9 activate
> no auto-summary
> no synchronization
> 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
> no bgp default ipv4-unicast
> bgp log-neighbor-changes
> neighbor 192.168.20.9 remote-as 69
> 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
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > 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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Received on Sun Jun 05 2011 - 07:29:50 ART