Folks, We are pursuing some work along the lines of studying BGP scalability in terms of churn evolution. One of the key mechanisms used by BGP to dampen the churn is the MRAI timer (Minimum Route Advertisement Interval).
From different vendors' specifications we find that:
1- Cisco enables MRAI by default for both route announcements and route withdrawals. 2- Juniper has a similar parameter called out-delay which is disabled by default. Of course these are default configurations, and we don't know if ISPs use them without any change. We would appreciate any input on the following questions: A- Is it common that ISPs change MRAI default configurations? If yes, then what decides the MRAI settings for both e-BGP and i-BGP sessions? B- Does anybody use a configuration where only route announcements are rate limited, and not explicit route withdrawals? C- Are there configurations where rate limiting is applied only to a subset of session? Best regards, Ahmed Elmokashfi Simula Research Laboratory.