Brocade Communications Systems Layer 3 Routing Configuration ICX 6650 - Manual (Page 344)

326 Brocade ICX 6650 Layer 3 Routing Configuration Guide
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BGP null0 routing
Figure 28 shows a topology for a null0 routing application example.
FIGURE 28 Example of a null0 routing application
The following steps configure a null0 routing application for stopping denial of service attacks from
remote hosts on the internet.
Configuration steps for BGP null0 routing
1. Select one switch, S6, 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
unused network address (199.199.1.1).
3. Set the local-preference to a value higher than any possible internal or external
local-preference (50).
4. Complete the route map by setting origin to IGP.
5. On S6, redistribute the static routes into BGP, using route-map route-map-name (redistribute
static route-map block user).
6. On S1, the router facing the internet, configure a null0 route matching the next-hop address in
the route-map (ip route 199.199.1.1/32 null0).
7. Repeat step 3 for all switches interfacing with the internet (edge corporate routers). In this
case, S2 has the same null0 route as S1.
8. On S6, configure the network prefixes associated with the traffic you want to drop. The static
route IP address references a destination address. You are required to point the static route to
the egress port, for example, Ethernet 1/1/2, and specify the tag 50, matching the route-map
configuration.
R1
AS 100
R2
R3
R6 R7 R5
R4
Internet