«

Can someone explain the reason for NOT using the "mask" keyword in a
BGP network statement? Ie.

Router bgp 65010
Network 1.1.1.1

VS.

Router bgp 65010
Network 1.1.1.1 mask 255.255.255.0

Thanks,

when you dont "no auto-summary" and want to announce 1.0.0.0/8

wrote:
> when you dont "no auto-summary" and want to announce 1.0.0.0/8

Could you please clarify this answer? I don't understand your response

Thank you

Hy,


If you are using the "no auto-summary" keyword:

-You must have a exact match in the IP routing table to appear the
network in the BGP routing table. For example:
- network 1.1.1.1/8 will appear in BGP if network 1.1.1.1/8
appear in the IP routing table.
- network 1.1.1.1/24 will appear in BGP if network 1.1.1.1/24
appear in the IP routing table.


If you are using the "auto-summary" keyword:

-You must have the classfull network or a subnet of this classfull
network in the IP routing table to appear the network in the BGP
routing table. For example:
- network 1.1.1.1/8 will appear in BGP if network 1.1.1.1/8
or 1.1.1.1/10.... exist in the IP routing table.
- network 1.1.1.1/24 will appear in BGP if network 1.1.1.1/24
or 1.1.1.1/26.... exist in the IP routing table.

CIAO

wrote:
> Can someone explain the reason for NOT using the "mask" keyword in a
> BGP network statement? Ie.
>
> Router bgp 65010
> Network 1.1.1.1
>
> VS.
>
> Router bgp 65010
> Network 1.1.1.1 mask 255.255.255.0
>
> Thanks,

Your reply was very informative but it is still unclear what the
difference is between using the bgp Mask keyword and NOT using the mask
keyword in bgp. could you clarify this specifically.

Thanks

Gararda wrote:
> Hy,
>
>
> If you are using the "no auto-summary" keyword:
>
> -You must have a exact match in the IP routing table to appear the
> network in the BGP routing table. For example:
> - network 1.1.1.1/8 will appear in BGP if network 1.1.1.1/8
> appear in the IP routing table.
> - network 1.1.1.1/24 will appear in BGP if network 1.1.1.1/24
> appear in the IP routing table.
>
>
> If you are using the "auto-summary" keyword:
>
> -You must have the classfull network or a subnet of this classfull
> network in the IP routing table to appear the network in the BGP
> routing table. For example:
> - network 1.1.1.1/8 will appear in BGP if network 1.1.1.1/8
> or 1.1.1.1/10.... exist in the IP routing table.
> - network 1.1.1.1/24 will appear in BGP if network 1.1.1.1/24
> or 1.1.1.1/26.... exist in the IP routing table.
>
> CIAO
>
> wrote:
> > Can someone explain the reason for NOT using the "mask" keyword in a
> > BGP network statement? Ie.
> >
> > Router bgp 65010
> > Network 1.1.1.1
> >
> > VS.
> >
> > Router bgp 65010
> > Network 1.1.1.1 mask 255.255.255.0
> >
> > Thanks,

Hy,

If you NOT use the mask keyword in the network stament, BGP use by
default the classfull network. For example:
- network 10.1.1.0, the network that BGP install will be
10.0.0.0/8, because the natural
mask of this network is a class A. (remember, you must consider
IP routing table,
auto-summary.....)

I hope this help you.

CIAO.

wrote:
> Your reply was very informative but it is still unclear what the
> difference is between using the bgp Mask keyword and NOT using the mask
> keyword in bgp. could you clarify this specifically.
>
> Thanks
>
> Gararda wrote:
> > Hy,
> >
> >
> > If you are using the "no auto-summary" keyword:
> >
> > -You must have a exact match in the IP routing table to appear the
> > network in the BGP routing table. For example:
> > - network 1.1.1.1/8 will appear in BGP if network 1.1.1.1/8
> > appear in the IP routing table.
> > - network 1.1.1.1/24 will appear in BGP if network 1.1.1.1/24
> > appear in the IP routing table.
> >
> >
> > If you are using the "auto-summary" keyword:
> >
> > -You must have the classfull network or a subnet of this classfull
> > network in the IP routing table to appear the network in the BGP
> > routing table. For example:
> > - network 1.1.1.1/8 will appear in BGP if network 1.1.1.1/8
> > or 1.1.1.1/10.... exist in the IP routing table.
> > - network 1.1.1.1/24 will appear in BGP if network 1.1.1.1/24
> > or 1.1.1.1/26.... exist in the IP routing table.
> >
> > CIAO
> >
> > wrote:
> > > Can someone explain the reason for NOT using the "mask" keyword in a
> > > BGP network statement? Ie.
> > >
> > > Router bgp 65010
> > > Network 1.1.1.1
> > >
> > > VS.
> > >
> > > Router bgp 65010
> > > Network 1.1.1.1 mask 255.255.255.0
> > >
> > > Thanks,

[maxfactor]

Hi, I read somewhere that auto-summary doesn't matter anything with network command. I tried myself to configure a router, and I can say that if I write

router bgp 1
network 10.0.0.0
auto-summary

ip route 10.10.0.0 255.255.0.0 null0

then

show ip bgp

shows no entries. Cisco student-guide says instead that with the auto-summary , any subnet of the major network specified would prompt the major to be installed in the bgp routing table. But it seems to be not the truth.

Thanks

[theapplebee]

BGP network mask is used for specify network / CIDR