Chapter 9
| General Security Measures
IPv6 Source Guard
– 340 –
ipv6 dhcp snooping (321)
ipv6 dhcp snooping vlan (326)
ipv6 source-guard This command configures the switch to filter inbound traffic based on the source IP
address stored in the binding table. Use the no form to disable this function.
Syntax
ipv6 source-guard sip
no ipv6 source-guard
Default Setting
Disabled
Command Mode
Interface Configuration (Ethernet)
Command Usage
â—† Source guard is used to filter traffic on an insecure port which receives
messages from outside the network or fire wall, and therefore may be subject
to traffic attacks caused by a host trying to use the IP address of a neighbor.
â—† This command checks the VLAN ID, IPv6 global unicast source IP address, and
port number against all entries in the binding table. Use the no ipv6 source
guard command to disable this function on the selected port.
â—† After IPv6 source guard is enabled on an interface, the switch initially blocks all
IPv6 traffic received on that interface, except for ND packets allowed by ND
snooping and DHCPv6 packets allowed by DHCPv6 snooping. A port access
control list (ACL) is applied to the interface. Traffic is then filtered based upon
dynamic entries learned via ND snooping or DHCPv6 snooping, or static
addresses configured in the source guard binding table. The port allows only
IPv6 traffic with a matching entry in the binding table and denies all other IPv6
traffic.
â—† Table entries include a MAC address, IPv6 global unicast address, entry type
(Static-IPv6-SG-Binding, Dynamic-ND-Snooping, Dynamic-DHCPv6-Snooping),
VLAN identifier, and port identifier.
â—† Static addresses entered in the source guard binding table with the ipv6
source-guard binding command are automatically configured with an infinite
lease time. Dynamic entries learned via DHCPv6 snooping are configured by
the DHCPv6 server itself.
◆ If IPv6 source guard is enabled, an inbound packet’s source IPv6 address will be
checked against the binding table. If no matching entry is found, the packet
will be dropped.
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