Bgp Null0 Routing - Dell PowerConnect B-RX Configuration Manual

BGP Null0 routing

BGP can use the null0 route to resolve its next hop. Thus, null0 route in the routing table (for
example, static route) is considered as a valid route by BGP. If the next hop for BGP resolves into a
null0 route, the BGP route is also installed as a null0 route in the routing table.
The null0 routing feature allows network administrators to block certain network prefixes, by using
null0 routes and route-maps. The combined use of null0 routes and route maps blocks traffic from
a particular network prefix, telling a remote router to drop all traffic for this network prefix by
redistributing a null0 route into BGP.
Figure 113
FIGURE 113
The following steps configure a null0 routing application for stopping denial of service attacks from
remote hosts on the internet.
Configuration steps
1. Select one router, Router 6, to distribute null0 routes throughout the BGP network.
2. Configure a route-map to match a particular tag (50) and set the next-hop address to an
3. Set the local-preference to a value higher than any possible internal or external
4. Complete the route map by setting origin to IGP.
BigIron RX Series Configuration Guide
53-1001810-01
shows a topology for a null0 routing application example.
Sample Null0 routing application
Internet
R1
AS 100
unused network address (199.199.1.1).
local-preference (50).
R2
R3
R5 R6
26
BGP Null0 routing
R4
R7
753