Allied Telesis VERSION 5.4.3-2.6, BGP4 manual How to adjust the eBGP advertisement interval

BGP and BGP4+ Introduction

How to adjust the eBGP advertisement interval

AS200	eBGP 30 second		AS300
	advertisement
		interval
2001:db8::80:1		2001:db8::80:2
Router 1			Router 2
Router ID 10.10.10.11			Router ID 10.10.10.12
			intro_bgp4+_3.eps

When a route advertised by BGP changes, BGP sends an Update message. If an advertised route is flapping, and becomes unavailable. Route flapping is often caused when an interface is unstable, and a flood of Update messages will occur. One approach to control the flooding of BGP messages is to configure the advertisement interval. With the default interval value of 30 seconds for eBGP neighbors, BGP routing updates are sent only every 30 seconds, even if a route is flapping many times during this 30 second interval.

To assign a different advertisement-intervalvalue for eBGP peers, use the following command in Router Configuration mode::

awplus(config-router)#

neighbor <neighborid> This command sets the minimum interval between sending advertisement-interval <time> eBGP routing updates with a 30 second eBGP default interval.

Use this command instead of the neighbor as-origination-interval (BGP and BGP4+) command for eBGP peers with prefixes not in the same AS for updates not in a local AS.

How to adjust the iBGP advertisement interval

AS200	iBGP 5 second
	advertisement
fe80::1	interval	vlan2
vlan1	fe80::2
Router 1		Router 2
Router ID 10.10.10.11		Router ID 10.10.10.12
		intro_bgp4+_2

With the default value of 5 seconds for iBGP neighbors, BGP routing updates are sent only every 5 seconds, even if a route is flapping many times during this 5 second interval.

To assign a different advertisement-intervalvalue for iBGP peers, use the following command in Router Configuration mode: :

awplus(config-router)#

neighbor <neighborid> This command sets the minimum interval between sending advertisement-interval <time> eBGP routing updates with a 5 second iBGP default interval.

BGP dampening can also be used to control the effects of flapping routes. See the BGP and BGP4+ Route Dampening section in this chapter, and the bgp dampening (BGP and BGP4+) command in the BGP and BGP4+ Commands chapter for more information.

Software Reference Supplement for SwitchBlade® x8112, x908, x900 and x610 Series Switches

C613-50032-01 REV D AlliedWare PlusTM Operating System - Software Version 5.4.3-2.6 1.37