- play_arrow Port Security
- play_arrow Port Security Overview
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- play_arrow IPSec
- play_arrow Understanding IPsec and Security Associations
- play_arrow IPsec Configurations and Examples
- play_arrow Configuring IPsec Security Associations
- play_arrow Using Digital Certificates for IPsec
- play_arrow Additional IPsec Options
- play_arrow Configuring IPsec Dynamic Endpoints
- play_arrow Additional ES and AS PIC Configuration Examples
- Example: ES PIC Manual SA Configuration
- Example: AS PIC Manual SA Configuration
- Example: ES PIC IKE Dynamic SA Configuration
- Example: AS PIC IKE Dynamic SA Configuration
- Example: IKE Dynamic SA Between an AS PIC and an ES PIC Configuration
- Example: AS PIC IKE Dynamic SA with Digital Certificates Configuration
- Example: Dynamic Endpoint Tunneling Configuration
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- play_arrow Digital Certificates
- play_arrow Configuring Digital Certificates
- Public Key Cryptography
- Configuring Digital Certificates
- Configuring Digital Certificates for an ES PIC
- IKE Policy for Digital Certificates on an ES PIC
- Configuring Digital Certificates for Adaptive Services Interfaces
- Configuring Auto-Reenrollment of a Router Certificate
- IPsec Tunnel Traffic Configuration
- Tracing Operations for Security Services
- play_arrow Configuring SSH and SSL Router Access
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- play_arrow Trusted Platform Module
- play_arrow MACsec
- play_arrow Understanding MACsec
- play_arrow MACsec Examples
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- play_arrow MAC Limiting and Move Limiting
- play_arrow MAC Limiting and Move Limiting Configurations and Examples
- Understanding MAC Limiting and MAC Move Limiting
- Understanding MAC Limiting on Layer 3 Routing Interfaces
- Understanding and Using Persistent MAC Learning
- Configuring MAC Limiting
- Example: Configuring MAC Limiting
- Verifying That MAC Limiting Is Working Correctly
- Override a MAC Limit Applied to All Interfaces
- Configuring MAC Move Limiting (ELS)
- Verifying That MAC Move Limiting Is Working Correctly
- Verifying That the Port Error Disable Setting Is Working Correctly
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- play_arrow DHCP Protection
- play_arrow DHCPv4 and DHCPv6
- play_arrow DHCP Snooping
- Understanding DHCP Snooping (ELS)
- Understanding DHCP Snooping (non-ELS)
- Understanding DHCP Snooping Trust-All Configuration
- Enabling DHCP Snooping (non-ELS)
- Configuring Static DHCP IP Addresses
- Example: Protecting Against Address Spoofing and Layer 2 DoS Attacks
- Example: Protecting Against DHCP Snooping Database Attacks
- Example: Protecting Against ARP Spoofing Attacks
- Example: Prioritizing Snooped and Inspected Packet
- Configuring DHCP Security with Q-in-Q Tunneling in Service Provider Style
- play_arrow DHCP Option 82
- play_arrow Dynamic ARP Inspection (DAI)
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- play_arrow IP Source Guard
- play_arrow Understanding IP Source Guard
- play_arrow IP Source Guard Examples
- Example: Configuring IP Source Guard on a Data VLAN That Shares an Interface with a Voice VLAN
- Example: Configuring IP Source Guard with Other EX Series Switch Features to Mitigate Address-Spoofing Attacks on Untrusted Access Interfaces
- Example: Configuring IP Source Guard and Dynamic ARP Inspection to Protect the Switch from IP Spoofing and ARP Spoofing
- Example: Configuring IPv6 Source Guard and Neighbor Discovery Inspection to Protect a Switch from IPv6 Address Spoofing
- Configuring IP Source Guard to Mitigate the Effects of Source IP Address Spoofing and Source MAC Address Spoofing
- Example: Configuring IP Source Guard and Dynamic ARP Inspection on a Specified Bridge Domain to Protect the Devices Against Attacks
- Example: Configuring IPv6 Source Guard and Neighbor Discovery Inspection to Protect a Switch from IPv6 Address Spoofing
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- play_arrow IPv6 Access Security
- play_arrow Neighbor Discovery Protocol
- play_arrow SLAAC Snooping
- play_arrow Router Advertisement Guard
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- play_arrow Control Plane Distributed Denial-of-Service (DDoS) Protection and Flow Detection
- play_arrow Control Plane DDoS Protection
- play_arrow Flow Detection and Culprit Flows
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- play_arrow Storm Control
- play_arrow Malware Protection
- play_arrow Juniper Malware Removal Tool
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- play_arrow Configuration Statements and Operational Commands
Understanding and Preventing Unknown Unicast Forwarding
Unknown unicast traffic consists of unicast packets with unknown destination MAC addresses. By default, the switch floods these unicast packets that traverse a VLAN to all interfaces that are members of that VLAN. Forwarding this type of traffic can create unnecessary traffic that leads to poor network performance or even a complete loss of network service. This flooding of packets is known as a traffic storm.
To prevent a traffic storm, you can disable the flooding of unknown unicast packets to all VLAN interfaces by configuring specific VLANs or all VLANs to forward all unknown unicast traffic traversing them to a specific interface. You can configure multiple VLANs to forward unknown unicast packets to the same interface or configure different interfaces for different VLANs. This channels the unknown unicast traffic traversing VLANs to specific interfaces instead of flooding all interfaces.
The unknown-unicast-forwarding feature is not supported on QFX10000 Series platforms.
Verifying That Unknown Unicast Packets Are Forwarded to a Single Interface
Purpose
Verify that a VLAN is forwarding all unknown unicast packets (those with unknown destination MAC addresses) to a single interface instead of flooding unknown unicast packets across all interfaces that are members of that VLAN.
This procedure uses Junos OS for EX Series switches with support for the Enhanced Layer 2 Software (ELS) configuration style. For ELS details see: Using the Enhanced Layer 2 Software CLI.
Action
(EX4300 Switches) Display the forwarding interface for unknown unicast packets for a VLAN (here, the VLAN name is v1):
user@switch> show configuration switch-options
unknown-unicast-forwarding {
vlan v1 {
interface ge-0/0/7.0;
}
}
(EX9200 Switches) Display the forwarding interface for unknown unicast packets:
user@switch> show forwarding-options
next-hop-group uuf-nhg {
group-type layer-2;
interface ge-0/0/7.0;
}
Meaning
The sample output from the show commands show that the unknown unicast forwarding interface for VLAN v1is interface ge-0/0/7.
Configuring Unknown Unicast Forwarding (ELS)
This task uses Junos OS for EX Series switches or QFX Series with support for the Enhanced Layer 2 Software (ELS) configuration style. For ELS details, see Using the Enhanced Layer 2 Software CLI
The unknown-unicast-forwarding feature is not supported on QFX10000 Series platforms.
Unknown unicast traffic consists of packets with unknown destination MAC addresses. By default, the switch floods these packets that traverse a VLAN to all interfaces associated with that VLAN. This flooding of packets is known as a traffic storm and can negatively impact network performance.
To prevent flooding unknown unicast traffic across the switch, configure unknown unicast forwarding to direct all unknown unicast packets within a VLAN to a specific interface. You can configure each VLAN to divert unknown unicast traffic to a different interface or use the same interface for multiple VLANs.
- Configuring Unknown Unicast Forwarding on EX4300 Switches
- Configuring Unknown Unicast Forwarding on EX9200 Switches
Configuring Unknown Unicast Forwarding on EX4300 Switches
To configure unknown unicast forwarding options on EX4300 switches:
Configuring Unknown Unicast Forwarding on EX9200 Switches
To configure unknown unicast forwarding on EX9200 switches, you must configure a flood filter and apply it to VLANs for which you want to configure unknown unicast forwarding. Flood filters are firewall filters that are applied only to broadcast, unknown unicast, and multicast (BUM) traffic. If a flood filter is configured, only traffic packets that are of the packet type unknown-unicast are forwarded to the interface on which unicast forwarding is configured. A next-hop group redirects the packets according to the action specified in the flood filter.
To configure the next-hop group that receives Layer 2 packets and then configure the interface to which these packets are forwarded:
Verifying That Unknown Unicast Packets Are Forwarded to a Trunk Interface
Purpose
Verify that a VLAN is forwarding all unknown unicast packets (those with unknown destination MAC addresses) to a single trunk interface instead of flooding unknown unicast packets across all interfaces that are members of the same VLAN.
Action
Display the forwarding interface for unknown unicast packets for a VLAN (here, the VLAN name is v1):
user@switch> show configuration ethernet-switching-options
unknown-unicast-forwarding {
vlan v1 {
interface ge-0/0/7.0;
}
}
Display the Ethernet switching table:
user@switch> show ethernet-switching table vlan v1 Ethernet-switching table: 3 unicast entries VLAN MAC address Type Age Interfaces v1 * Flood - All-members v1 00:01:09:00:00:00 Learn 24 ge-0/0/7.0 v1 00:11:09:00:01:00 Learn 37 ge-0/0/3.0
Meaning
The sample output from the show configuration ethernet-switching-options command shows that the unknown unicast forwarding interface for
VLAN v1 is interface ge-0/0/7. The show
ethernet-switching table command shows that an unknown unicast
packet is received on interface ge-0/0/3 with the destination
MAC address (DMAC) 00:01:09:00:00:00 and the source MAC
address (SMAC) of 00:11:09:00:01:00. This shows that the
SMAC of the packet is learned in the normal way (through the interface ge-0/0/3.0), while the DMAC is learned on interface ge-0/0/7.
Configuring Unknown Unicast Forwarding (CLI Procedure)
Unknown unicast traffic consists of packets with unknown destination MAC addresses. By default, the switch floods these packets to all interfaces associated with a VLAN. Forwarding such traffic to interfaces on the switch can create a security issue.
To prevent flooding unknown unicast traffic across the switch, configure unknown unicast forwarding to direct all unknown unicast packets within a VLAN out to a specific trunk interface. From there, the destination MAC address can be learned and added to the Ethernet switching table. You can configure each VLAN to divert unknown unicast traffic to different trunk interfaces or use one trunk interface for multiple VLANs.
For Junos OS for EX Series switches or QFX Series with support for the Enhanced Layer 2 Software (ELS) configuration style, see Configuring Unknown Unicast Forwarding (ELS).
The unknown-unicast-forwarding feature is not supported on QFX10000 Series platforms.
To configure unknown unicast forwarding options:
Before you can configure unknown unicast forwarding within a VLAN, you must first configure that VLAN.
