R3303-HP HSR6800 Routers IP Multicast Configuration Guide
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• Some maliciously configured hosts can forge bootstrap messages to fool routers and change RP
mappings. Such attacks often occur on border routers. Because a BSR is inside the network whereas
hosts are outside the network, you can protect a BSR against attacks from external hosts by enabling
the border routers to perform neighbor checks and RPF checks on bootstrap messages and discard
unwanted messages.
• When a router in the network is controlled by an attacker or when an illegal router is present in the
network, the attacker can configure this router as a C-BSR and make it win BSR election to control
the right of advertising RP information in the network. After being configured as a C-BSR, a router
automatically floods the network with bootstrap messages. Because a bootstrap message has a TTL
value of 1, the whole network will not be affected as long as the neighbor router discards these
bootstrap messages. Therefore, with a legal BSR address range configured on all routers in the
entire network, all these routers will discard bootstrap messages from out of the legal address
range.
The preventive measures can partially protect the security of BSRs in a network. If a legal BSR is controlled
by an attacker, the preceding problem will still occur.
Because the BSR and the other devices exchange a large amount of information in the BIDIR-PIM domain,
provide a relatively large bandwidth between the C-BSRs and the other devices.
For C-BSRs interconnected through a GRE tunnel, configure static multicast routes to make sure the next
hop to a C-BSR is a tunnel interface. For more information about static multicast routes, see "Configuring
multicast routing and forwarding."
To configure a C-BSR:
Ste
p
Command
Remarks
1. Enter system view.
system-view N/A
2. Enter public network PIM view
or VPN instance PIM view.
pim [ vpn-instance
vpn-instance-name ]
N/A
3. Configure an interface as a
C-BSR.
c-bsr interface-type
interface-number [ hash-length
[ priority ] ]
No C-BSRs are configured by
default.
4. Configure a legal BSR
address range.
bsr-policy acl-number
Optional.
No restrictions on BSR address
range by default.
Configuring a BIDIR-PIM domain border
As the administrative core of a BIDIR-PIM domain, the BSR sends the collected RP-Set information in the
form of bootstrap messages to all routers in the BIDIR-PIM domain.
A BIDIR-PIM domain border is a bootstrap message boundary. Each BSR has its specific service scope.
A number of BIDIR-PIM domain border interfaces partition a network into different BIDIR-PIM domains.
Bootstrap messages cannot cross a domain border in either direction.
Perform the following configuration on routers that you want to configure as the PIM domain border.
To configure a BIDIR-PIM domain border:
Ste
p
Command
Remarks
1. Enter system view.
system-view N/A