- Written by Saurabh Kumar
- Posted on October 24, 2024
- Updated on October 24, 2024
- 4498 Views
Today in any WAN deployment, customers are required to configure path metrics in load balance policy to program a set of best paths in dataplane. Path metrics are multi-dimensional, it include loss, latency, jitter, and load of path. It is not very intuitive to come up with exact values for these metrics as they are highly dependent on the type of application and geographical locations of routers. Also these path metrics keep changing and except for a few apps that require strict max characteristics on latency, jitter or loss, the other apps are able to tolerate variances in metrics.
- Written by Lavanya Conjeevaram
- Posted on March 31, 2017
- Updated on April 3, 2017
- 11492 Views
Overlay IPv6 routing over VXLAN Tunnel is simply routing IPv6 packets in and out of VXLAN Tunnels, similar to
- Written by Aditi Vaidya
- Posted on August 23, 2019
- Updated on February 4, 2022
- 10963 Views
This document describes a few enhancements done in Wireless Manager (WM) release 8.8 in respect of AP firmware
- Written by Sahil Midha
- Posted on October 16, 2025
- Updated on January 16, 2026
- 1721 Views
Packet trimming is a novel method for end-to-end congestion notification. When a packet is dropped in the MMU due to congestion, the dropped packet is trimmed and forwarded to the intended receiver with a new configured DSCP value. Upon receiving a trimmed packet, the receiver can perform appropriate handling to reduce transmission rate or retransmit any lost packets. The feature supports matching criteria via ingress traffic policy for selecting which packets should be trimmed when they get dropped in the MMU. Similarly, the rewritten DSCP is specified on a per egress port basis for trimmed packets egressing out of the switch to the intended destination.This feature is supported for protocols IPv4, IPv6 and SRv6.
- Written by Robert Rada
- Posted on April 22, 2024
- Updated on January 8, 2025
- 6402 Views
By default, the scheduling between parent interfaces and the attached shaped subinterfaces is done in strict priority mode where the parent interface has higher priority than shaped subinterfaces. Subinterfaces that are not shaped use the same queues as the parent so the traffic on these subinterfaces will also have strict priority over shaped subinterfaces.
- Written by Dhruba Jyoti Pokhrel
- Posted on February 20, 2023
- Updated on February 20, 2023
- 8185 Views
With the 14.0 release, you can add device passwords and AP-Server Key passphrase as defined in the password policy. The passwords are based on the password policy and password settings that you configure in CV-CUE.
- Written by Mihyar Baroudi
- Posted on December 8, 2015
- Updated on May 29, 2019
- 10467 Views
This feature provides the capability to mirror special L2 control frames, called the Pause or Priority Flow Control
- Written by Anoop Dawani
- Posted on September 30, 2015
- Updated on July 13, 2018
- 11122 Views
Policy Based Routing (PBR) provides the flexibility of routing according to custom defined policies in a way that
- Written by Brandon Edgren
- Posted on May 1, 2015
- Updated on May 1, 2015
- 8584 Views
Prior to EOS 14.15.0F, if a single packet hit both a PBR and an ACL rule, then only the hardware counters corresponding
- Written by Xiaohui Gong
- Posted on August 19, 2025
- Updated on August 19, 2025
- 2014 Views
On MLAG devices, flood traffic over the peer link follows split-horizon rules to avoid duplicate delivery of packets on MLAG interfaces. However, when one of the MLAG devices becomes inactive, peer-link flooding can cause double delivery or Layer 2 loops. To mitigate this risk, peer-link forwarding restriction was introduced. As of 4.34.0F, support was added for peer-link forwarding restriction when MLAG is enabled but not fully formed to the primary or secondary role. In this transitional state, only MLAG VLANs carrying MLAG control (PDU) traffic are allowed over the peer link. As of 4.34.2F, peer-link forwarding restriction is enabled by default. Users may still disable the feature manually as needed.
- Written by Lavanya Conjeevaram
- Posted on June 29, 2016
- Updated on March 29, 2018
- 11705 Views
The per port per VLAN feature allows application of QoS policies for IP, IPv6 and non IP traffic on a per port per VLAN
- Written by Ahirnish Pareek
- Posted on February 8, 2017
- Updated on February 6, 2022
- 10125 Views
DCS 7010T. DCS 7050X. DCS 7250X. DCS 7260X. DCS 7280E, DCS 7280R. DCS 7300X. DCS 7320X. DCS 7500E,
- Written by Kushagra Mohan
- Posted on March 18, 2020
- Updated on December 20, 2024
- 12944 Views
This feature enables per port TC-To-COS mapping, where TC represents Traffic-Class and COS represents Vlan tag PCP bits. While at present there is a global TC-To-COS mapping, we can use the TC-To-COS feature to create custom profiles which can be applied to the required interfaces.
- Written by Lavanya Conjeevaram
- Posted on June 29, 2016
- Updated on June 29, 2016
- 11446 Views
Per VLAN MAC Learning is a feature to enable/disable mac learning per vlan instead of per port. Using this feature with
- Written by Prashant Kumar
- Posted on April 30, 2025
- Updated on January 21, 2026
- 2912 Views
Policy-map counters can be configured to display per-interface counters for all class-maps attached to all successfully programmed policy-maps. The feature is not enabled by default and has to be configured through the command line interface. When enabled, the output of the show command will display both per-interface and aggregate counters.
- Written by Johnny Chen
- Posted on April 25, 2022
- Updated on March 9, 2026
- 12338 Views
The Per-MAC ACL feature provides the functionality to apply an IPv4/IPv6 ACL to a 802.1x supplicant instead of applying them on the port that the supplicant is behind. This allows for more flexible and specific traffic policies to be defined for supplicants trying to access certain resources on the network.
- Written by Cormac Keane
- Posted on September 11, 2025
- Updated on September 11, 2025
- 1503 Views
This feature introduces per-nexthop MPLS label allocation for the IPv4-unicast default-route and the IPv6-unicast default-route. Previously, BGP-VPN VRFs only supported a per-VRF label scheme. With a per-VRF label scheme, each BGP-VPN supported AFI-SAFI (i.e. IPv4-unicast and IPv6-unicast) in the BGP-VPN VRF is allocated a single "per-VRF" label that will be shared by all the AFI-SAFI’s routes. When the routes are exported as BGP-VPN routes, all the routes will be exported with the same "per-VRF" VPN label. In the Label FIB (LFIB), each allocated "per-VRF" label is associated with an ip-lookup action inside their corresponding BGP-VPN VRF.
- Written by Radek Szymanski
- Posted on December 24, 2024
- Updated on January 20, 2025
- 4107 Views
The software for Syslog, NTP and SNMP used in EOS resolves hostnames at service start-up. It’s possible that during service operation, the configured host becomes unavailable and the configuration needs to be set to a different host to continue the service. The problem is that such change requires manual restart of the service. Even if the hostname doesn’t change and only the underlying address is updated at the DNS server, the administrator has to manually reset service configuration.
- Written by Gaurav Chaudhari
- Posted on July 18, 2025
- Updated on July 18, 2025
- 2110 Views
If Dot1x Mac based authentication ( MBA ) is disabled, supplicant discovery is attempted by sending periodic multicast identity requests. These requests are transmitted at a fixed interval, which is 60 seconds. This transmission continues until a successful authentication of an EAPOL supplicant is achieved. With MBA enabled, supplicant discovery also relies on multicast identity requests. However, the transmission interval is set to 30 seconds and the transmission count is set to 3.
- Written by Sahil Midha
- Posted on May 1, 2015
- Updated on May 20, 2015
- 9348 Views
Permitting traffic during ACL updates has been available for traffic steering in tap aggregation mode since EOS
- Written by Siva Kumar
- Posted on October 14, 2024
- Updated on October 14, 2024
- 4421 Views
Hosts in a branch need to access internet bound services. In traditional deployments, edge routers in branches are connected to the internet via WAN port. To secure the internal network from the internet we have ACLs( Access Control Lists ) to filter the traffic in/out from the WAN port. If we want to filter the traffic into the port we have ingress ACL, egress ACL filters the traffic out of the port. By default, without any ACL configuration present on the WAN port, we accept every traffic coming to the WAN port.
- Written by Jared Dulmage
- Posted on October 29, 2025
- Updated on October 29, 2025
- 1408 Views
Priority-Flow-Control (PFC) Fair Adaptive Dynamic Threshold (FADT) configuration facilitates efficient utilization of packet buffer resources for both lossy and lossless traffic. Reserve headroom buffer resources to absorb in-flight packets for congested, lossless flows. Assign default or user-defined PFC profiles to interface/PFC priority pairs, called Priority Groups (PG), to dynamically manage packet buffer usage and assertion of PFC pause.
- Written by Rajat Jain
- Posted on February 8, 2017
- Updated on February 4, 2022
- 11246 Views
PFC (Priority based Flow Control) is a flow control mechanism used in RDMA environments. PFC provides a link level
- Written by Veluchamy Dinakaran
- Posted on September 30, 2015
- Updated on September 30, 2015
- 10889 Views
This feature enables detection of egress queues that are unable to transmit packets for prolonged periods of time
- Written by Mukund PB
- Posted on June 20, 2022
- Updated on May 8, 2025
- 11783 Views
Priority Flow Control (PFC) Watchdog feature monitors interfaces for priority-flow-control Pause storm. If such a storm is detected on no-drop enabled priorities, it takes actions such as:
- Written by Mihyar Baroudi
- Posted on December 8, 2015
- Updated on June 14, 2019
- 11327 Views
DCS 7050X/X2/X3 series. DCS 7060X/X2/X3 series. In previous releases, PFC Watchdog supported only queues
- Written by Rahul Kumar Singh
- Posted on August 18, 2022
- Updated on October 11, 2024
- 14143 Views
This article is intended to discuss how to configure the Phone VLAN on an Arista switch.
- Written by Neeraj Joseph
- Posted on April 23, 2018
- Updated on September 12, 2025
- 13333 Views
The PHY test pattern CLI can be used to check the quality of the physical layer for an Ethernet interface. This is done by
- Written by Sandeep Betha
- Posted on January 31, 2022
- Updated on February 25, 2025
- 18843 Views
PIM External Gateways (PEGs) allow an EVPN overlay multicast network to interface with an external PIM domain. They can be used to interconnect two data centers using an external PIM domain in between them.
- Written by Padmini Misra
- Posted on September 30, 2015
- Updated on September 30, 2015
- 11124 Views
PIM VRF feature adds VRF support to these existing multicast protocols: PIM SM, PIM BSR, IGMP and MSDP.
- Written by Santosh Kumar
- Posted on December 22, 2017
- Updated on May 2, 2024
- 11640 Views
PIM Static Source Discovery (SSD) is a feature implemented as part of PIM-SM. Familiarity with setting up and configuring PIM-SM (Sparse Mode) and PIM-SSM (Source-Specific Multicast) is assumed.
- Written by Prachi Modi
- Posted on May 8, 2025
- Updated on May 8, 2025
- 2306 Views
With the 19.0 release of CV-CUE, you can place the switches on the floor map by dragging them on the floor map.
- Written by Lavanya Conjeevaram
- Posted on June 29, 2016
- Updated on February 8, 2017
- 10570 Views
Ingress policing on front panel ports is supported on DCS 7010X and DCS 7050X since EOS4.14.0F. When ingress policing
- Written by Jaffar Hameedabdul
- Posted on November 22, 2017
- Updated on November 22, 2017
- 10333 Views
Traffic is managed through policy maps that apply data shaping methods to specific data streams. A policy map is a data
- Written by Sambath Kumar Balasubramanian
- Posted on December 20, 2024
- Updated on October 3, 2025
- 4909 Views
EOS provides support for the use of IPsec to establish and maintain IPsec tunnels. This feature adds support for redirecting traffic matching on traffic policy rules to an IPSec tunnel.
- Written by Sahil Midha
- Posted on February 8, 2017
- Updated on February 7, 2022
- 10281 Views
QoS profiles have been applicable on fabric and front panel ports across all platforms from EOS 4.17.0F release
- Written by Satya Viswanathan
- Posted on April 22, 2015
- Updated on July 2, 2015
- 9685 Views
Policy Based Routing (PBR) is a feature that is applied on routable ports, to preferentially route packets. This is
- Written by Yan Hua
- Posted on August 22, 2025
- Updated on January 5, 2026
- 1662 Views
This document covers the usage of port-breakout CLI to break a port evenly into multiple interfaces. In the context of this document, a port is a logical entity that holds a list of interfaces, in most cases this is equivalent to the front panel transceiver cage.
- Written by Ryan Izard
- Posted on April 23, 2025
- Updated on April 23, 2025
- 2883 Views
In previous versions, the DMF Controller had a hidden CLI command to change the log level from INFO to WARN for a particular port down log in the DMF Controller. This hidden command has been removed in DMF 8.7.0. The following is an example of the hidden command:
- Written by Gabor
- Posted on April 18, 2024
- Updated on May 22, 2025
- 9428 Views
Port mirroring is used to send a copy of packets seen on one port to a network monitoring connection on another switch port. Port mirroring is commonly used with network probes or other monitoring devices; examples include intrusion detection devices, latency analyzers, or packet capture and protocol analysis tools.
- Written by Ioana Costea
- Posted on March 31, 2017
- Updated on September 15, 2025
- 11544 Views
Persistent port security is a feature which ensures that port-security MAC cache is preserved across link flap and system reload. The feature is useful when it is desired to have the same set of already allowed secure MAC addresses on a particular interface after system reload or link flaps. There are separate global configurations to enable persistent port-security for shutdown and protect mode. A command to clear the MAC entries and secure MAC cache for interfaces with port-security configured has been added.
- Written by Mihyar Baroudi
- Posted on December 8, 2015
- Updated on December 21, 2015
- 11995 Views
Port Security: Protect mode (PortSec Protect) is newly added to the Port Security feature and is designed to restrict
- Written by Ioana Costea
- Posted on April 25, 2025
- Updated on April 25, 2025
- 3323 Views
Introduced in the 4.34.0F release, the maximum links feature allows users to specify the number of active members in both LACP and static port-channels. If active members become inactive due to configuration changes or link failure, previously restricted members can become active. This ensures the port-channel remains operational, preventing disruptions even if all initial active members fail.
- Written by Utkarsha Verma
- Posted on June 29, 2016
- Updated on June 29, 2016
- 10246 Views
Port Channel member status logging on Arista switches allows logging of Ethernet interfaces joining or leaving a
- Written by Padmanabh Ratnakar
- Posted on April 20, 2021
- Updated on October 22, 2025
- 19977 Views
The postcard telemetry (GreenT - GRE Encapsulated Telemetry) feature is used to gather per flow telemetry information like path and per hop latency. For network monitoring and troubleshooting flow related issues, it is desirable to know the path, latency and congestion information for flows at different times.
- Written by Tom Meng
- Posted on November 11, 2019
- Updated on May 7, 2025
- 11297 Views
Power management is a way to limit the total available power to be used for Power over Ethernet (PoE) ports. Without power management, the total amount of power that the power supply units (PSU) are able to provide is used. Power management can be used to create power redundancies. For example, if a system has 2 1050W PSUs, the feature can set the total available power to be 800W for PoE. With this configuration, 1 PSU is sufficient to power the system and the unused PSU acts as a backup source, thus giving the system a 1+1 redundancy.
- Written by Julie Powell
- Posted on October 23, 2024
- Updated on October 23, 2024
- 4324 Views
View PTP counters to identify the types of messages being sent and received by PTP-enabled devices. Use this to troubleshoot issues with your network PTP configuration and connectivity. When announce and sync messages are present but delay request messages are missing, for instance, it may suggest that a host is having trouble locking to the boundary clock.
- Written by Yin Chen
- Posted on October 30, 2023
- Updated on March 13, 2026
- 9334 Views
This article provides a general introduction to Precision Time Protocol (PTP) supported within EOS. PTP is aimed at distributing time with sub-microsecond accuracy. PTP support is based on the IEEE-1588 specification for version 2 of the protocol.
- Written by Jack Jiang
- Posted on October 10, 2025
- Updated on October 10, 2025
- 1606 Views
Precision Time Protocol (PTP) is a protocol aimed at distributing time between devices with sub-microsecond accuracy. PTP support is based on the IEEE-1588 specification for version 2 of the protocol. cEOS-lab is a containerised image which provides a portable way to run EOS in a virtualised environment. With this support, multiple virtual labs can be spun up to be used for testing and learning of the PTP feature.
- Written by Eric Lanini
- Posted on March 3, 2023
- Updated on October 11, 2024
- 9308 Views
Precoding is used to help reduce the burst error length of DFE (Decision Feedback Equalizer) error events with PAM-4 modulation
