Interfaces and Hardware Component Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Releases

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Interfaces and Hardware Component Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Releases

802.1Q VLAN

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This topic describes 802.1Q VLANs on the Cisco 8000 Series Router, including how the IEEE 802.1Q protocol standard uses VLAN tags to divide networks into logically separated broadcast domains.


VLAN is a logical network configuration that

  • enables devices on different physical LAN segments to communicate as if they share a single wire, when in fact, they are located on several different LAN segments

  • provides flexibility for user and host management as they are based on logical instead of physical connections, and

  • optimizes bandwidth allocation and resource usage.

Table 1. Feature History Table

Feature Name

Release Information

Feature Description

802.1Q VLAN

Release 26.1.1

Introduced in this release on: Centralized Systems (8400 [ASIC:K100]) )(select variants only*)

*This feature is now supported on Cisco 8404-SYS-D routers.

802.1Q VLAN

Release 25.4.1

Introduced in this release on: Fixed Systems (8010 [ASIC: A100])(select variants only*)

*This feature is supported on:

  • 8011-32Y8L2H2FH

  • 8011-12G12X4Y-A/D

802.1Q VLAN

Release 25.1.1

Introduced in this release on: Fixed Systems (8010 [ASIC: A100])(select variants only*)

*This feature is supported on Cisco 8011-4G24Y4H-I routers.

802.1Q VLAN

Release 24.4.1

Introduced in this release on: Fixed Systems (8700) (select variants only*)

* The 802.1Q VLAN functionality is now extended to the Cisco 8712-MOD-M routers.

802.1Q VLAN

Release 24.3.1

Introduced in this release on: Fixed Systems (8200 [ASIC: Q200, P100], 8700 [ASIC: P100])(select variants only*); Modular Systems (8800 [LC ASIC: Q100, Q200, P100])(select variants only*)

* The 802.1Q VLAN functionality is now extended to:

  • 8212-48FH-M

  • 8711-32FH-M

  • 88-LC1-52Y8H-EM

  • 88-LC1-36EH+A8:B12

  • 88-LC1-12TH24FH-E

802.1Q VLAN

Release 24.2.11

Introduced in this release on: Modular Systems (8800 [LC ASIC: P100]) (select variants only*)

A VLAN is a logical grouping of devices across different LAN segments that communicate as if they are on the same physical network, offering flexibility in user management, bandwidth allocation, and resource optimization. The IEEE 802.1Q protocol standard helps divide large networks into smaller segments to efficiently manage broadcast and multicast traffic, enhancing bandwidth usage and security.

* This feature is now supported on routers with 88-LC1-36EH line cards.

Double-Tagged 802.1ad Encapsulation Options for Layer 3 Physical and Bundle Subinterfaces

Release 24.4.1

Introduced in this release on: Fixed Systems (8200 [ASIC: Q200, P100], 8700 [ASIC: P100, K100]); Centralized Systems (8600 [ASIC:Q200]); Modular Systems (8800 [LC ASIC: Q100, Q200, P100])

The support for Double-Tagged 802.1ad Encapsulation Options for Layer 3 Physical and Bundle Subinterfaces is now extended to all Systems in the Cisco 8000 Series Routers.

Double-Tagged 802.1ad Encapsulation Options for Layer 3 Physical and Bundle Subinterfaces

Release 7.3.2

This feature enables you to increase the number of VLAN tags in an interface and an subinterface. You can enable this feature either on a physical interface or a bundle interface. When you configure this feature with the dual tag, interfaces check for IP addresses along with MAC addresses.

Verified Scalability Limits:

  • Total number of VLAN tags in an interface and a subinterface with single tag: 4094

  • Total number of VLAN tags in an interface and a subinterface with double tag: 4094 * 4094

The IEEE 802.1Q protocol standard provides several benefits for network management:

  • It divides large networks into smaller segments to reduce unnecessary broadcast and multicast traffic.

  • It enhances security between internal network segments.

  • It establishes a standard method for inserting VLAN membership information into Ethernet frames.

Note

Cisco IOS XR software supports VLAN subinterface configuration on 40Gigabit, HundredGig, FourHundredGig, and bundle interfaces.


802.1Q tagged frames

The IEEE 802.1Q tag-based VLAN is a network configuration method that

  • uses an extra tag in the MAC header to identify frame membership across bridges

  • supports both static and dynamic VLAN creation, and

  • facilitates VLAN and Quality of Service (QoS) priority identification.

The VLANs can be created statically by manual entry or dynamically through Generic Attribute Registration Protocol (GARP) VLAN Registration Protocol (GVRP).

The IEEE 802.1Q frame structure includes specific components that switches process across the network:

  • The VLAN ID associates a frame with a specific VLAN.

  • A tagged frame measures four bytes longer than an untagged frame.

  • The Tag Protocol Identifier (TPID) resides within the type and length field of the Ethernet frame.

  • The Tag Control Information (TCI) starts after the source address field of the Ethernet frame.