LevelOne FGL-2870 - Manual (Page 553)

General Security Measures
4-187
4
• When enabled, traffic is filtered based upon dynamic entries learned via
DHCP snooping, or static addresses configured in the source guard binding
table.
• Table entries include a MAC address, IP address, lease time, entry type
(Static-IP-SG-Binding, Dynamic-DHCP-Binding, VLAN identifier, and port
identifier.
• Static addresses entered in the source guard binding table with the ip
source-guard binding command (page 4-188) are automatically configured
with an infinite lease time. Dynamic entries learned via DHCP snooping are
configured by the DHCP server itself.
• If the 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 page 4-179), 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 the 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
(dynamically learned via DHCP snooping or manually configured) are not
yet configured, the switch will drop all IP traffic on that port, except for
DHCP packets.
Example
This example enables IP source guard on port 5.
Related Commands
ip source-guard binding (4-188)
ip dhcp snooping (4-179)
ip dhcp snooping vlan (4-180)
Console(config)#interface ethernet 1/5
Console(config-if)#ip source-guard sip
Console(config-if)#