Address-family under router BGP vs neighbor configuration mode

[dtran]

Hello everyone, hope everyone is doing well !!!

I have a couple questions around address-family command. If I understand correctly, network advertisement and summarization occur within the address-family but what's the difference of having address-family and network advertisement under router BGP configuration mode vs under neighbor configuration mode ? and in what scenario would you use it under router BGP mode vs neighbor configuration mode ? 

Thanks in advance !!!

Danny

[MHM Cisco World]

As i know under address family for ios and under neighbor for ios xr.

Two different Cisco OS.

[dtran]

Thanks MHM !!

BGP will running on a pair of Nexus 93180YC-FX switches.

Danny

[MHM Cisco World]

Use this mode for advanced features such as limiting the number of prefixes allowed for this neighbor and removing private AS numbers for eBGP.

This from Cisco guide why we need address family under neighbor mode

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https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus9000/sw/6-x/unicast/configuration/guide/l3_cli_nxos/l3_bgp.html

[MHM Cisco World]

...

[Jon Marshall]

There is a very good explanation here - 

https://community.cisco.com/t5/routing/when-to-use-bgp-address-family/td-p/1927840

Jon

[dtran]

Thanks Jon for sharing the link !!! very helpful ...

Danny