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Overview

IP Source Guard (IPSG) is a security feature implemented in network switches to mitigate IP address spoofing attacks. It generally works by ensuring that incoming packets on a network interface have a source IP address that matches an entry in the IP source guard binding table. Traffic from other IP addresses is dropped.

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By default, IP source guard is disabled. It must be enabled on each port where guarding is required.

Configuration Notes and Constraints

When configuring IP source guard, consider the following points:

  • IP source guard can only be configured on Layer 2 physical ports.

  • The interface that enables IPSG cannot be a DHCP snooping trust interface.

  • IPSG has a higher priority than PBR (Policy-Based Routing) and 802.1X (downloadable ACL and dynamic ACL). When IPSG is enabled on the ingress interface and VLAN to which a packet belongs, the packet is subject to IPSG verification. As a result, it bypasses both PBR and 802.1X ACL matching processes.

  • If a packet that matches the IP source guard entry also matches an ACL rule (such as a firewall filter ACL), and the action of the ACL rule is discard, then the packet will be discarded by the ACL regardless of other configurations.

  • IPSG is not supported in MLAG scenarios.

Configuring IP Source Guard

Configuring IP Source Guard involves the following steps:

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run show ip-source-guard binding [interface <interface-name>]

Configuration Example

Networking Requirements

Figure 1.     IP Source Guard Configuration Example

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Code Block
admin@PICOS# run show ip-source-guard binding
Total ipsg host count:     2
Mac-Address         Ip-Address      Interface       VLAN      Type         Filter-Type         Status
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3f:2c:99:51:48:01   10.10.10.22     ge-1/1/1        10        static                   ip   ip+mac              effective
54:9c:99:d3:09:5c   20.1.1.10       ge-1/1/2        20        dhcp-snooping    ip+mac              effective

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