BGP routing black hole and anti ring

BGP The routing black hole of

  Formation of routing black holes ：

because BGP The agreement supports indirect connection and neighbor building , Therefore, there may be BGP Protocol spanning is not running BGP Protocol router . Lead to BGP After routing , The control level can reach , But at the data level , After not running BGP The router of the protocol cannot pass . Form a routing black hole .

The solution ：

1. stay R3 Admiral BGP The routing information of the protocol is republished to IGP among

2 Directly in R4 Up operation BGP agreement

3.MPLS

Synchronization mechanism ：

When a router from its own IBGP The peer learns a BGP When routing , He will not be able to tell himself EBGP peers , Unless he comes back from IGP We learned this route from the protocol

BGP My guard ring

Routing loops ： The phenomenon that data packets are constantly transmitted between a series of routers but cannot reach the expected destination network . When there are errors in the routing information of multiple stations or the path to the unreachable destination network , There may be a loop .

BGP The anti ring mechanism used --- Horizontal segmentation mechanism

EBGP The horizontal division of --- Apply to EBGP Between peers

BGP The protocol will record the route in the routing entry AS Number ----AS_PATH （ This attribute can be completed in addition to EBGP Outside the horizontal division of , It can also be used as the basis for choosing the road .）--- The received BGP In the routing entry , Among them AS_PATH Properties of the , If there is a local AS Number , Will be rejected .

 IBGP The horizontal division of --- Apply to IBGP Between peers

When a router from a IBGP Learn something from the peer BGP When routing , He will not be able to announce this route information to others IBGP Peer relationship . because IBGP Limitations of horizontal segmentation , Lead to IBGP The routing information between peers can only be transferred

a jump , In this case , May cause communication obstacles .

  Solution ：

1, Build a company IBGP Peer relationship --- The drawback of this method is 1, Building a whole neighborhood will lead to an increase in resource consumption ;2, It may cause the scalability of the network to decline low .

2, Routing reflectors

3, The federal