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16
STEP 1
STEP 2
STEP 3
319
•
DHCP Snooping must be globally enabled in order to enable IP Source Guard on an
interface.
•
IP source guard can be active on an interface only if:
-
DHCP Snooping is enabled on at least one of the port's VLANs
-
The interface is DHCP untrusted. All packets on trusted ports are forwarded.
•
If a port is DHCP trusted, filtering of static IP addresses can be configured, even
though IP Source Guard is not active in that condition by enabling IP Source Guard on
the port.
•
When the ports status changes from DHCP untrusted to DHCP trusted, the static IP
address filtering entries remain in the Binding database, but they become inactive.
•
Port security cannot be enabled if source IP and MAC address filtering is configured
on a port.
•
IP Source Guard uses TCAM resources and requires a single TCAM rule per IP Source
Guard address entry. If the number of IP Source Guard entries exceeds the number of
available TCAM rules, the extra addresses are inactive.
Filtering
If IP Source Guard is enabled on a port then:
•
DHCP packets allowed by DHCP Snooping are permitted.
•
If source IP address filtering is enabled:
-
IPv4 traffic: Only traffic with a source IP address that is associated with the port is
permitted.
-
Non IPv4 traffic: Permitted (Including ARP packets).
IP Source Guard Work Flow
To configure IP Source Guard:
Enable (DHCP Snooping)
Define the VLANs on which DHCP Snooping is enabled in the (DHCP Snooping)
Settings
page.
Configure interfaces as trusted or untrusted in the (DHCP Snooping)
Cisco Sx350, SG350X, SG350XG, Sx550X & SG550XG Series Managed Switches, Firmware Release 2.2.5.x
Properties
page.
Security
IP Source Guard
Interface
Interface Settings
page.
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