HP A5500 SI Switch Series Configuration Manual page 364

Some maliciously configured hosts can forge bootstrap messages to fool routers and change RP
1.
mappings. Such attacks often occur on border routers. Because a BSR is inside the network
whereas hosts are outside the network, a BSR can be protected against attacks from external hosts
after you enable the border routers to perform neighbor checks and RPF checks on bootstrap
messages and to discard unwanted messages.
When an attacker controls a router in the network or when the network contains an illegal router,
2.
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 it is configured as a C-BSR, the router automatically
floods the network with bootstrap messages. Because a bootstrap message has a hop limit 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.
These preventive measures can partially protect the security of BSRs in a network. However, if an
attacker controls a legal BSR, the problem will still occur.
Follow these steps to complete basic BSR configuration:
To do...
Enter system view
Enter IPv6 PIM view
Configure an interface as a C-BSR
Configure a legal BSR address
range
NOTE:
Because a large amount of information needs to be exchanged between a BSR and the other devices in
the IPv6 PIM-SM domain, a relatively large bandwidth should be provided between the C-BSR and the
other devices in the IPv6 PIM-SM domain.
Configuring an IPv6 PIM domain border
As the administrative core of an IPv6 PIM-SM domain, the BSR sends the collected RP-set information in
the form of bootstrap messages to all routers in the IPv6 PIM-SM domain.
An IPv6 PIM domain border is a bootstrap message boundary. Each BSR has its specific service scope.
IPv6 PIM domain border interfaces partition a network into different IPv6 PIM-SM domains. Bootstrap
messages cannot cross a domain border in either direction.
Perform the following configuration on routers that can become an IPv6 PIM domain border.
Follow these steps to configure an IPv6 PIM border domain:
To do...
Enter system view
Enter interface view
Use the command...
system-view
pim ipv6
c-bsr ipv6-address [ hash-length [
priority ] ]
bsr-policy acl6-number
Use the command...
system-view
interface interface-type interface-
number
352
Remarks
—
—
Required
No C-BSRs are configured by
default.
Optional
No restrictions by default
Remarks
—
—