Aggregate-address and attribute-list for BGP
We sometimes use summary route of BGP, for example, for HQ site's CE router of IP-VPN since it has lots of prefixes. Some IP-VPN carrieres often implements restriction of prefix number per site.. For example, CE router speak OSPF on their LAN interface and it receives routes below prefix. 10.0.1.0/24 ・ ・ 10.0.20.0/24 In such a case, for Cisco configuration -------- router bgp 65000 redistribute ospf 10 aggregate-address 10.0.0.0 255.0.0.0 summary-only -------- Above is just one example for this kind of case. But when HQ CE router receives subnet of this summary route like 10.0.100.0/24, it might be a bit troublesome.. Because if there's some outage on LAN side and CE router cannot receive any 10.0.x.0/24, the CE router still advertise summary route 10.0.0.0/8 to BGP because summary route is still created from 10.0.100.0/24! For example, in case of redundant topoloy (2CE and 2 circuit), what...