Planet IGSW-2840 User Manual page 488

Default Setting
Disabled
Command Mode
Interface Configuration (Ethernet)
Command Usage
• Source guard is used to filter traffic on an unsecure port which receives messages from outside the network or firewall,
and therefore may be subject to traffic attacks caused by a host trying to use the IP address of a neighbor.
• Setting source guard mode to "sip" or "sip-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. Use the no source guard command to disable this
function on the selected port.
• 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, Static-DHCP-Binding), VLAN identifier, and port identifier.
• Static addresses entered in the source guard binding table with the ip source-guard binding command are
automatically configured with an infinite lease time. Dynamic entries learned via DHCP snooping are configured by the
DHCP server itself; static entries include a manually configured lease time.
• 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, 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
Example
This enables IP source guard on port 5.
Console(config)#interface ethernet 1/5
Console(config-if)#ip source-guard sip
Console(config-if)#
Related Commands
ip source-guard binding
ip dhcp snooping
ip dhcp snooping vlan
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User's Manual of IGSW-2840