HP 6125XLG Configuration Manual page 161

Configuring a legal BSR address range enables filtering of BSMs based on the address range, thereby
preventing a maliciously configured host from masquerading as a BSR. The same configuration must be
made on all routers in the IPv6 PIM-SM domain. The following describes the typical BSR spoofing cases
and the corresponding preventive measures:
• Some maliciously configured hosts can forge BSMs 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 BSMs and to discard unwanted
messages.
When an attacker controls a router in the network or when an illegal router is present in the network,
•
the attacker can configure the router as a C-BSR and make it win the BSR election to advertise RP
information in the network. After a router is configured as a C-BSR, it automatically floods the
network with BSMs. Because a BSM has a hop limit value of 1, the whole network will not be
affected as long as the neighbor router discards these BSMs. Therefore, with a legal BSR address
range configured on all routers in the network, all these routers can discard BSMs from out of the
legal address range.
These preventive measures can partially protect the BSR in a network. However, if an attacker controls a
legal BSR, the problem still exists.
When you configure a C-BSR, reserve a relatively large bandwidth between the C-BSR and the other
devices in the IPv6 PIM-SM domain.
To configure a C-BSR:
Step
1. Enter system view.
2. Enter IPv6 PIM view.
3. Configure a C-BSR.
4. (Optional.) Configure a legal
BSR address range.
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.
To configure an IPv6 PIM border domain:
Step
1. Enter system view.
2. Enter interface view.
Command
system-view
ipv6 pim
c-bsr ipv6-address [ scope
scope-id ] [ hash-length
hash-length | priority priority ] *
bsr-policy acl6-number
Command
system-view
interface interface-type
interface-number
154
Remarks
N/A
N/A
By default, no C-BSR is configured.
By default, no restrictions are
defined.
Remarks
N/A
N/A