BGP network statement mask issue

[hfakoor222]

I have a router with Loopback interfaces

when I do my bgp network statement it's not letting me advertise a 192.168.3.1/224 or a 192.168.3.65/192                                    however it is letting me advertise a 192.168.3.0/224 and a 192.168.3.65/192. Can someone explain to me why this behavior is happening? For examp[le I want to advertise the 192.168.3.65/192 routes and not 192.168.3.64/192 so why is it forcing me to choose? Does it have something to do with the prefixing? 

[Flavio Miranda · Accepted solution]

Hi

If you want to advertise 192.168.3.65 you need to use /32 cause 192.168.3.65 is an IP address and not a network. 

 The network is 192.168.3.64/192

Thats why the protocol allow .64 and not .65. 

[Kanan Huseynli]

Hi,

the correct statement for BGP route advertisement with network command is as below:

network [subnetwork_ID] mask [subnetwork_mask] , hence the first parameter should be subnetwork_ID, not IP address of interface, but subnetwork ID of the subnet to which interface IP belongs to. Or you may advertise any route from routing table, but again with subnetwork_ID (basically, prefix should be mentioned, not IP address from the range).

In your screen, network 192.168.3.0 mask 255.255.255.224 works, because it is 192.168.3.0/27 which is exact prefix (subnetwork) and its mask.

192.168.3.65 mask 255.255.255.192 which is the same as 192.168.3.65/26 will not work, because it is IP from the range, you should mention the first IP from the range (network ID) - like 192.168.3.64 mask 255.255.255.192.

[hfakoor222]

Thank you

[MHM Cisco World]

This normal , bgp will accept this network only if the mask is 255.255.255.255

You use loopback with 224 and 192'

Check netwrok ID of this subnet/subney mask or you can use 

Show ip route check how route inject this subnet in RIB

Use it same as it appear in RIB and bgp will accpet it

[MHM Cisco World]

I want to advertise specific host from subnet'

Sorry there is no way I know

[hfakoor222]

Thanks