TAP vs. SPAN

For most security and networking monitoring applications there is no need to examine live network traffic. In fact, it is almost counterproductive lest one inadvertently block or disrupt live traffic. As a result, two common techniques are used to copy or mirror data. Both techniques replicate network traffic without disrupting the natural flow of data and are often referred to as “passive” or “out-of-band”.

The first technique is called an “optical TAP” where the term “TAP” is always capitalized because it is an acronym for “Test Access Point.” The TAP is a non-powered, hardware device that makes a full copy of network data without affecting network traffic. Garland Technology is a well-known manufacturer of TAPs and there is further information on their website. For the sake of completeness, I should mention that copper TAPs are also available, but they are much less common as optical fiber is the medium of choice for most backbone links in an enterprise, government or service provider network.

The other technique is a SPAN or mirror port on an Ethernet switch. SPAN is an acronym for “Switch Port Analyzer.” This is a configurable option on most advanced Ethernet switches from companies such as Cisco or Arista Networks. A network administrator configures the traffic from specific Ethernet ports on a given switch to be replicated or mirrored out another port. This naturally creates the desired traffic data copy which is forwarded on to security or network monitoring appliances.

Host CPU Offload Product Features Summary
wdt_ID Speed 1G 10G 10G 10G 10G/40G 10G/40G 100G 100G 100G 100G
1 Model ANIC-4Ku ANIC-20Ku ANIC-40Ku ANIC-40Kq ANIC-80Ku ATLAS-1000
Platform
ANIC-100Kq ANIC-200Ku ANIC-200K
Flex
ANIC-200Kq
2 Port/Type 4 X 1G SFP 2 X 10GSFP+ 4 X 10GSFP+ 1 X 40G4
X 10GQSFP+
2 X
40G8 X
10GQSFP+
SFP+
2 X
40GQSFP4
X10GSFP+
1 X
100GQSFP28
2 X
100GCFP4
2 X
40G2 X
100GQSFP28
2 X
100GQSFP28
3 PCIe Interface Gen3 x8 Gen3 x8 Gen3 x8 Gen3 x8 Gen3 x8 Gen3 x8 Gen3 x16 Gen3 x16 Gen3 x16 Gen3 x16
4 Dimensions
(H x L inches)
4.25 x 6.5   4.25 x 6.25 4.25 x 6.25 4.25 x 6.25 4.25 x 6.25 1.75 x12.28x14 4.25 x 10.5 4.25 x 10.5 4.25 x 6.5 4.25 x 10.5
5 Memory 32MB 4G 4G 4G 4G 16/32G 12G 12G 8G 12G
6 Timestamp 5.7 nS 5.7 nS 5.7 nS 5.7 nS 5.7 nS 5.7 nS 4 nS 4 nS 4 nS 4 nS
7 100% Packet
Capture
8 Gigamon, Arista
Timestamp
9 Packet Merging
10 Packet Parsing

About Accolade

Accolade is the technology leader in FPGA-based Host CPU Offload and 100% Packet Capture PCIe NIC’s and Scalable 1U Platforms. Accolade’s line of 1-100GE products enable 100% packet capture, flow classification, flow shunting, deduplication, packet filtering and more. Our customers are global leaders in network monitoring & cybersecurity applications as well as in the network test and measurement, telecom and video stream monitoring markets.

FPGA Acceleration Features

100% Packet Capture | Flow Classification | Flow Shunting | Precise Time Stamping | Packet Merging | Packet Slicing | Packet Parsing | Packet Filtering | Deduplication | Host Packet Buffer | Packet Steering | Direct Memory Access (DMA) | Statistics (RMON1)

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