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DANZ Table of Contents

Posted on December 23, 2014 by

Tap Aggregation Introduction to Tap Aggregation Basic Use of Aggregation Groups Tab Aggregation Basic Settings Before You Start Filtering with Port ACLs Tap Aggregation VLAN List Filtering Tap Aggregation Traffic Steering Deep Packet Inspection Truncation on Tap and Tool Ports LLDP on Tap Ports Common Challenges with TapAgg TapAgg Glossary Advanced Mirroring Introduction to Port Mirroring Filtering with Port ACLs Latency Analyzer (LANZ) LANZ Architectures and Configuration LANZ Buffer Tuning Timestamping TimeStamping on the 7150 Timestamping Deep Dive and Frequent Questions Optics Tap Aggregation Optics Selection  

40G TapAgg BiDi Design

Posted on June 18, 2018 by

Arista QSFP BiDi optics allow both transmit and receive signals, to travel on the same fiber slice. The QSFP BiDi design provides 40Gbps (20Gbps egress & 20Gbps ingress on each fiber slice) bandwidth using the duplex MMF (OM3, & OM4) cable. This way one can leverage the existing cabling infrastructure to upgrade BW from 10Gbps to 40Gbps ( see diagram 1). The BiDi optics provides a number of benefits and some are listed below: ▪   Fiber replacement not required when moving from 10Gbps to 40Gbps ▪   Lower CAPEX as 75% less fiber comparing parallel cable (40G SR4) ▪   Interoperable with Industry standard...
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Tap Aggregration Tip: Popping MPLS tags for Untagged or VLAN based Tools

Posted on May 12, 2018 by

In Tap Aggregation scenarios common in WAN and Service Provider environments, MPLS tags are present.  Many of the analysis tools do not understand these tags and so the Arista DANZ feature set allows for these to be removed.  This functionality has been around since 4.15.0F however initially had the limitation that the traffic would always be sent out the Tool port with a VLAN tag.  However, some tools not only do not understand MPLS, but also VLAN tags, so this tip describes how to deal with both 802.1q and untagged scenarios. Step 1:  Configure MPLS pop/strip on the Tap port:...
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Analyzing Packet Header Timestamps in Wireshark

Posted on April 14, 2017 by

Arista Packet Header Timestamps EOS 4.18.1F added header time stamping of all packets received on any tap interface in Tap Aggregation mode on the 7500/7280E and 7500/7280R. Full details on the implementation can be found in the feature’s TOI: https://eos.arista.com/eos-4-18-1f/tap-aggregation-ingress-header-time-stamping/ Since the timestamp is a new ethernet header, Wireshark doesn’t yet have a built in dissector for the protocol. We can write a dissector in Lua to do this for us. Header Format First we need to understand the new header format. The timestamp header is a new Ethernet/L2 header consisting of the Arista EtherType (0xD28B), a two-byte protocol subtype of 0x1, a...
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Understanding Deduplication in Tap Aggregation (NPB)

Posted on October 26, 2015 by

  1) What is deduplication ? Deduplication in the context of packet broker networks (Tap Aggregation) is the ability to detect duplicates of a packet, allowing only the first packet and dropping other iterations of the same packet.   2) Hardware impacts the Deduplication performance Deduplication, like many features, requires certain hardware characteristics to be supported by the silicon (network processor), which is the foundation of hardware packet processing and forwarding in networking/Ethernet equipment. It allows matching packet, manipulating, and making forwarding decisions in hardware.   2.1) Processing performance The Arista switches are based on high performance network processors of different...
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Latency Analyzer (LANZ) Architectures and Configuration

Posted on March 11, 2015 by

Introduction   Arista Latency Analyzer, or LANZ, is a technology that tracks and logs buffer congestion and latency in real time.  The visibility provided by LANZ of network hot-spots and microburst oversubscription gives the network operator greater insight into when problems are occurring on the network and why.  With LANZ you will know when congestion happened, track the sources of congestion, and be able to export real-time events to external applications.  LANZ also shows the effect of packet buffering on an application as well as monitors and records packet drops during network congestion.  It is an invaluable tool which allows...
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sFlow Generation for Legacy Networks with Tap Aggregation (NPB / Matrix switch)

Posted on February 24, 2015 by

  sFlow is a standard hadware sampling available on all the Arista platforms, providing rich statistical information on all ports. sFlow is available in Tap Aggregation mode, allowing additional use cases of Tap Aggregation than traffic analysis on analyzer tools: Retro-fitting sFlow to legacy infrastructure Distributed analysis This article focuses on Retro-fitting sFlow to legacy infrastructure.   1) sFlow vs Netflow sFlow is a sampling mechanism implemented in hardware: Widely available on non-legacy platforms, and widely supported on collectors/monitoring software sFlow requires minimal local processing which contrast with Netflow that is very CPU-intensive, making Netflow poorly suitable for any high performance...
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DANZ – Tap Aggregation optics / transceivers selection

Posted on February 23, 2015 by

This articles clarifies certain criteria that are important to consider in the design of a Network Packet Broker (NPB) aggregating traffic from various sources. For distance reasons, the main type of media used in tap aggregation is optical (multimode or single mode), therefore this article mainly focuses on these media.   1) Understanding Optical Budgets Multiple factors contribute to the degradation of optical signals Fiber attenuation Insertion loss (e.g. connectors, patch panels and splices) Fiber type mismatch (e.g. connecting 50/125MMF to 62.5/125MMF) Over-bending of fibre plant Intermediate passive devices (e.g. taps, attenuators or mode filters)   Media Type Approximate Loss...
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DANZ Tap Aggregation – Basic settings – Before you start

Posted on February 23, 2015 by

Several Arista switches support DANZ feature set for Tap Aggregation. The tap aggregation mode is a mere configuration (1-2 lines) that transform a high performance L2/L3 switch into a Tap Aggregator (NPB). This mode require certain considerations: 1) Tap aggregation – How to selecting the exclusive mode That tap aggregation mode is exclusive to part of a switch of the whole switch. Parts of the switch that are excluded from the Tap Aggregation mode can work either in fully L2/L3 forwarding mode (normal switching mode), or in simple hub mode. The options available vary per platforms, as per the below list....
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Deep Packet Inspection with Tap Aggregation

Posted on December 24, 2014 by

Introduction In this article we will focus on the Deep Packet Inspection access list enhancements available in Tap Aggregation Exclusive mode on the Arista 7150 series switches. Deep Packet Inspection (DPI) is an Access List enhancement that was introduced in EOS 4.14.0.F. This feature allows the administrator to inspect and match additional bytes in the packet header after the Layer 2, Layer 3 or Layer 4 header. DPI was designed to be utilized while in Tap Aggregation exclusive mode. Typical Use cases for DPI are: Identifying custom fields in Day zero attacks SLA Enforcement via identifying illegal content Behavioural targeting...
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Data Analyzer (DANZ) Glossary

Posted on December 23, 2014 by

Access List (ACL) The switch configuration used for the purpose of filtering Layer 2, Layer 3, or Layer 4 traffic. See Filtering with Port ACLs Advanced Mirroring An Arista feature set which includes support for filtered, multi-destination mirroring, mirroring to EOS of data plane traffic, advanced load-sharing, and packet truncation.   Aggregation Group A configuration or grouping of Tap and Tool ports together where traffic from all Tap ports in a group will be replicated to all Tool ports in the same group.  A tool port can be a member of multiple aggregation groups whereas a tap port is allowed...
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DANZ Tap Aggregation – Filtering on inner Q-in-Q header, and stripping outer header – At the same time

Posted on December 16, 2014 by

  This article documents the ability, for the Arista 7150S in Tap Aggregation mode, to selectively filter on inner Q-in-Q header, and also strip the outer  header on egress, effectively allowing a granular selection of what Q-tagged traffic tools will be receiving. Let’s take as traffic example some Q-in-Q traffic: Outer Q-header (Eth-type 0x88a8) – STAG – VLAN ID = 100 Inner Q-header (Eth-type 0x8100) – CTAG – VLAN ID = 101, 102   Packet capture example for this Q-in-Q traffic:   7150S(config)#bash sudo tcpdump -nni mirror0 [...] 22:23:44.040896 00:ab:00:00:02:23 > 00:1c:73:86:00:69, ethertype 802.1Q-QinQ (0x88a8), length 1020: vlan 100, p...
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Basic Use of Aggregation Groups

Posted on December 10, 2014 by

Introduction Aggregation groups provide a means of grouping tool ports to simplify the mapping of a tap port to multiple tools and allow grouping of alike applications. In current releases, each tap port can only be bound to one default aggregation group at any time. A tool port however, can simultaneously be a member of multiple aggregation groups. This is important as it allows multiple tools or tool servers to receive any of the multiple traffic flows input to the tap ports. The Tap Aggregation operator can for example have an IDS/IPS tool receiving the same traffic as an application...
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Common challenges with TAP aggregation

Posted on December 10, 2014 by

Introduction Capturing raw network packet data, whether it be from a mirror port or through an aggregation infrastructure, is often perceived to be a complex task. In reality, most of the anomalies or limitations faced by those starting out with capture have simple explanations and are usually not due to problems with the source devices but instead the capturing tool. This article provides a brief of commonly reported issues and some suggested avenues of investigation. Timestamping Timestamps missing or corrupt Check timestamping is configured correctly to match the hosts’ expectations (i.e. is the host looking in the right place for...
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Truncation on Tap and Tool Ports

Posted on December 10, 2014 by

Introduction EOS supports truncation on ingress and egress. In this article we will focus on how it can be applied in tap aggregation exclusive mode, on the Arista 7150 line of switches. Please refer to the supported features matrix for other hardware platforms. Truncation is the ability to remove unwanted or unneeded bytes from the packet at a configurable or fixed starting byte position, it may also be referred to as ‘Packet Slicing’. This is useful in situations where the data of interest is contained within the headers or early in the packet payload. It can be used to remove...
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LLDP on Tap ports

Posted on December 10, 2014 by

Introduction As of EOS 4.14.0F for Arista 7150 line of switches and EOS 4.20.1F for Arista 7500/7280 lines of switches, users of the tap aggregation features can benefit from visibility gained from LLDP on tap ports. Neighbor information will now be processed by the CPU and made available via the EOS CLI. Allows the tap aggregation administrator to view neighbor information for verification and troubleshooting. This article details the use of LLDP neighbor information on tap ports in tap aggregation exclusive mode. Show LLDP commands work in Tap Aggregation Exlcusive mode as they do in normal switching mode, no configuration...
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Introduction to TAP aggregation

Posted on December 10, 2014 by

Introduction Traditional approaches to network monitoring rely on the ongoing collection of generic, high level statistics such as interface utilization from a selection of network devices to detect trends or anomalies in service availability. Such metrics are naturally limited in the level of granularity they can provide and often only provide a hint of real underlying network conditions without providing any visibility into per-application activity or performance. Traditionally, reactive and localized packet capture would be employed to determine the cause of the performance degradation.  However the manual nature of needing to configure packet capture and mirroring and then physically attach...
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TAP Aggregation – Traffic Steering

Posted on December 10, 2014 by

Introduction This article details the ability of the Tap Aggregator to redirect, or steer, traffic away from the aggregation group that the Tap port belongs to.  This capability allows for a more granular focus and control on individual, or multiple, traffic flows ingressing the Tap Aggregator. The traffic steering capability uses MQC (QoS style) policy and class maps combined with standard access-lists to perform this function.  The feature also allows for the configuration of an identity VLAN different from the identity VLAN associated with the Tap port.  This article details the configuration steps necessary to achieve this functionality. The following...
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Leveraging Deep Inspection and Traffic Steering for monitoring SIP environments

Posted on December 10, 2014 by

Introduction With the expansion of SIP (Session Initiation Protocol) and RTP (Real-time Transport Protocol) for IP based telephony applications, enterprises and carriers alike have a requirement to track and capture calls or parts of calls for the purposes of performance analysis and forensic/legal monitoring requirements. This post documents a powerful use for Deep Inspection and Traffic Steering features to deliver a highly scaleable yet cost effective solution for stateful load-sharing of monitored VoIP services, avoiding the need for proprietary hardware (such as FPGA based accelerator modules). As the volumes of calls grow, it is clear that traffic will need to...
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Tap Aggregation – Filtering with Port ACLs

Posted on November 5, 2014 by

  1) Introduction   This article details the filtering of traffic across the Tap Aggregator by using port ACL. The filters allow granular selection of Layer2, Layer3, and Layer4 traffic on a per-port basis. The following other features might also be of interest, but are out of scope of this article: VLAN membership filters Traffic Steering   2) Filtering Overview   The well known MAC and IP Access-List filtering is used to filter traffic in Tap Aggregation mode, just like it does in switching mode. The Layer2/3/4 ACLs can be applied on Tap ports, ingress on Tool ports, egress  ...
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