H3C Technologies H3C S10500 Series Switches - Manual (Page 394)

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1. 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 to discard unwanted messages.
2. If an attacker controls a router in the network or if the network contains an illegal router, 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 you configure a router 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... Use the command... Remarks
Enter system view system-view —
Enter IPv6 PIM view pim ipv6 —
Configure an interface as a C-BSR
c-bsr ipv6-address
[ hash-length [ priority ] ] Required
No C-BSRs are configured by default.
Configure a legal BSR address
range
bsr-policy acl6-number
Optional
No restrictions by default
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 you want to configure as an IPv6 PIM domain border.
Follow these steps to configure an IPv6 PIM border domain:
To do... Use the command... Remarks
Enter system view system-view —
Enter interface view
interface interface-type
interface-number
—
Configure an IPv6 PIM domain
border
pim ipv6 bsr-boundary
Required
No IPv6 PIM domain border is
configured by default