Zte ZXR10 5900E Series Configuration Manual page 140

ZXR10 5900E Series Configuration Guide (IPv4 Routing)
Parameter
<peer-group-name>
Configuring BGP Route Advertisement
l BGP Route Advertisement Rules
The routes to be advertised by BGP have to exist in IGP routing table already. The
source of BGP route updating is that inject IGP routing information to BGP. It has
an influence on the stability of Internet routes directly. There are two route injection
methods, dynamic injection and static injection.
Dynamic injection is divided into two types, full dynamic injection and selective
dynamic injection.
Full dynamic injection means that all IGP routes are redistributed (Redistribution) to
BGP. This method is very easy to configure but controllability is weak and low efficient.
Selective dynamic injection means that inject a part of IGP routes to BGP (use
network command). This method verifies address and mask first, which improves
controllability and efficiency. In this way, the error routing information can be avoided
to inject.
However, no matter which method is adopted, the routes will be unstable. That
because dynamic injection totally depends on IGP information. When route flapping
occurs on IGP routes, BGP route update will be affected. Lots of updating packets
are generated because of the unstable routes, and the bandwidth will be wasted
heavily. To make up this disadvantage, route dampening and aggregation can be
adopted on the border.
Static injection solves the unstable routes greatly. It injects static routes to BGP.
Static routes are added manually, so it is influenced by IGP route flapping. Therefore,
the repeated updating will be prevented by the stability. However, if the subnetwork
partition is not very clear, static injection also brings data flow blocking.
In conclusion, there are three BGP route advertisement methods.
Use network command to advertise routes.
à
Use redistribute command to redistribute the routes learned by other protocols
à
to BGP.
Use BGP route aggregation to advertisement.
à
l Advertising Routes by network Command
The routes to be advertised by BGP have to exist in IGP routing table already.
The common method of BGP route advertisement is to select the network segment to
advertise by the network command. This command specifies the destination network
segment and mask, and then the routes which match with the rule accurately will enter
into BGP routing table. The routes will be filtered and advertised.
SJ-20150114102049-003|2015-01-15 (R1.0)
Description
Name of the peer group
5-16
ZTE Proprietary and Confidential