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3
Configuring the Switch
Command Usage
• Setting source guard mode to SIP (Source IP) or SIP-MAC (Source IP and MAC)
enables this function on the selected port. Use the SIP option to check the VLAN
ID, source IP address, and port number against all entries in the binding table. Use
the SIP-MAC option to check these same parameters, plus the source MAC
address. If no matching entry is found, the packet is dropped.
• When enabled, traffic is filtered based upon dynamic entries learned via DHCP
snooping (see "DHCP Snooping Configuration" on page 3-102), or static
addresses configured in the source guard binding table.
• If IP source guard is enabled, an inbound packet's IP address (SIP option) or both
its IP address and corresponding MAC address (SIP-MAC option) will be checked
against the binding table. If no matching entry is found, the packet will be dropped.
• Filtering rules are implemented as follows:
- If DHCP snooping is disabled (see 3-102), IP source guard will check the VLAN
ID, source IP address, port number, and source MAC address (for the SIP-MAC
option). If a matching entry is found in the binding table and the entry type is
static IP source guard binding, the packet will be forwarded.
- If DHCP snooping is enabled, IP source guard will check the VLAN ID, source
IP address, port number, and source MAC address (for the SIP-MAC option). If
a matching entry is found in the binding table and the entry type is static IP
source guard binding, or dynamic DHCP snooping binding, the packet will be
forwarded.
- If IP source guard if enabled on an interface for which IP source bindings have
not yet been configured (neither by static configuration in the IP source guard
binding table nor dynamically learned from DHCP snooping), the switch will drop
all IP traffic on that port, except for DHCP packets.
Command Attributes
• Filter Type – Configures the switch to filter inbound traffic based source IP
address, or source IP address and corresponding MAC address. (Default: None)
• None – Disables IP source guard filtering on the port.
• SIP – Enables traffic filtering based on IP addresses stored in the binding table.
• SIP-MAC – Enables traffic filtering based on IP addresses and corresponding
MAC addresses stored in the binding table.
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