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BGP soft in - any negative effects?

PAUL TRIVINO
Participant
Participant

I am familiar with inbound soft reconfiguration - but I do not know of any negative impacts this can have.  Can anyone say if there are any negatives about this?

Paul

1 Accepted Solution

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Peter Paluch
Hall of Fame Cisco Employee Hall of Fame Cisco Employee
Hall of Fame Cisco Employee

Hi Paul,

To my best knowledge, having inbound soft reconfiguration will increase your memory footprint and may increase the CPU utilization slightly as the BGP code will need to crawl through more entries in its table, skipping the ones-would-be-filtered-out. Otherwise, I am not aware of any outspokenly harmful effects.

Then again, if you do not know exactly you need it, you don't need it BGP implementations support the Route Refresh functionality for years now, and turning the soft reconfiguration on does not bring any additional functionality from the viewpoint of re-applying inbound policies.

Best regards,

Peter

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3 Replies 3

Peter Paluch
Hall of Fame Cisco Employee Hall of Fame Cisco Employee
Hall of Fame Cisco Employee

Hi Paul,

To my best knowledge, having inbound soft reconfiguration will increase your memory footprint and may increase the CPU utilization slightly as the BGP code will need to crawl through more entries in its table, skipping the ones-would-be-filtered-out. Otherwise, I am not aware of any outspokenly harmful effects.

Then again, if you do not know exactly you need it, you don't need it BGP implementations support the Route Refresh functionality for years now, and turning the soft reconfiguration on does not bring any additional functionality from the viewpoint of re-applying inbound policies.

Best regards,

Peter

What I was trying to fix is getting:

ROUTER#sh ip bgp nei a.b.c.d received-routes

% Inbound soft reconfiguration not enabled on a.b.c.d

I have plenty of CPU and memory on the device in question.  Thanks for the reply!

Paul

Route refresh capability consumes the bw by sending messages and the entire adj_rib_out table when ever there is a change in the inbound policy. Where as soft reconfig inbound , applies the modified policy on the routes which are stored separetly on adj_rib_in for that specific neighbor, there by saves bw.

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