08-26-2017 09:27 AM - edited 03-05-2019 09:03 AM
Hello,
Is it possible to delay an eBGP peering? I have several sites with redundant ASR-1006 routers that seem to take up 30 seconds to complete their GetVPN registration after a reload. Since BGP becomes active (placing the router in the forwarding path) long before GetVPN registration is complete, any traffic that attempts to traverse that link/router is dropped. This also occurs at sites where the Key Servers are local and reachable via LAN connectivity. As all sites have redundant routers, a newly reloaded router would be able to reach a Key Server without depending upon the BGP routes being learned, so I would like to find a way to delay the BGP peering re-establishment after it has been lost due to a circuit failure or router reload, for 30 - 60 seconds, to allow GetVPN registration to complete.
Thanks,
08-26-2017 11:32 AM
Hi,
I am not sure if you can alter the bgp phases from idle to established, but you delay the routing advertisement
neighbor x.x.x.x advertisement-interval xx
https://www.cisco.com/c/en/us/td/docs/ios/iproute_bgp/command/reference/irg_book/irg_bgp3.html
HTH
08-27-2017 12:15 AM
08-27-2017 02:08 PM
Hello,
in addition to the other posts, and I don't know if that is feasible in your particular situation, you could use two EEM applets, one that removes the eBGP neigbhor when the link is down, and puts it back into the configuration when the link is up. The second action is delayed by 30 seconds. This would (generically) look like below (in the example, the event timer countdown is 30 seconds, which means the eBGP neighbor will be added 30 seconds after the link has been up):
event manager applet remove_bgp
event syslog pattern "%LINK-3-UPDOWN: Interface FastEthernet0, changed state to down"
action 1.1 cli command "enable"
action 1.2 cli command "config t"
action 1.3 cli command "router bgp 1"
action 1.4 cli command "no neighbor 192.168.1.2 remote-as 2"
action 1.5 cli command "end"
action 1.6 cli command "wr mem"
event manager applet delay_bgp
event syslog pattern "%LINK-3-UPDOWN: Interface FastEthernet0, changed state to up"
action 1.0 cli command "event timer countdown time 30"
action 1.1 cli command "enable"
action 1.2 cli command "config t"
action 1.3 cli command "router bgp 1"
action 1.4 cli command "neighbor 192.168.1.2 remote-as 2"
action 1.5 cli command "end"
action 1.6 cli command "wr mem"
08-29-2017 10:32 AM
event manager applet delay_bgp
event syslog pattern "%LINK-3-UPDOWN: Interface FastEthernet0, changed state to up"
action 1.4 cli command "neighbor 192.168.1.2 remote-as 2"
event manager applet remove_bgp
event syslog pattern "%LINK-3-UPDOWN: Interface FastEthernet0, changed state to down"
action 1.4 cli command "no neighbor 192.168.1.2 remote-as 2"
If you replace action 1.4's with "no neighbot 192.168.1.2 shutdown" and "neighbor 192.168.1.2 shutdown"that this would be a safer way to do it since you don't lose any further manipulation of bGP on your peers such as activation, route-maps, filter-lists, etc.
best regards,
tim
08-29-2017 11:35 AM
Thanks to everyone for the replies. I am looking into the EEM script now but for some reason, the delay function doesn't see to be working. I need to test more but the EEM options seems like it might work for what I need to accomplish.
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