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On Aug 22, 2012, at 14:26 , Mike Horwath <[log in to unmask]> wrote: > On Wed, Aug 22, 2012 at 01:55:53PM -0700, Owen DeLong wrote: >> Agreed. However, I would say that for those with Cisco gear where an >> address swap requires removing the address from the interface (and >> thus downing their BGP sessions), making the new address primary and >> the old address secondary could, ideally, be done during the switch >> upgrade and thus avoid an additional outage. > > conf term > int bajlliongmillibit0/0 > ip address secondary-ip secondary-netmask > ^z > write mem > > notice I didn't remove the primary address...nor the old secondary. > > Should work? > That will replace the old address with the new one. If your peers haven't all done the same thing and you haven't modified all your BGP sessions accordingly, then bad things happen. If you meant: ... ip address secondary-ip secondary-netmask secondary Then that postpones the problem to the day you deprecate the primary address. In either case, you forgot the IPv6 address. ;-) Suggestion instead... During switch maintenance... conf term int bajilliongmillibit0/0 ip address new-ip new-netmask ip address old-ip old-netmask secondary ipv6 address new-ip new-netmask ipv6 address old-ip old-netmask secondary In this way, yes, there will be a brief time where the old-ip disappears from the router and those BGP sessions will shut down accordingly. However, since they will already be down for the switch maintenance, no harm. Then, when everyone has completed their address migration, removing the secondary address is easy and doesn't cause any outage. Owen ######################################################################## To unsubscribe from the MICE-DISCUSS list, click the following link: http://lists.iphouse.net/cgi-bin/wa?SUBED1=MICE-DISCUSS&A=1