10-Gigabit Ethernet Switch Performance Testing - Ixia

Developing the
Right Test
Methodology
Understanding the stress points in a
switch allows the development of a test
methodology that can focus on testing
these areas. The test methodology should
address multiple layers, and could include
measuring for:
• Wire speed unicast data throughput
and latency for Layer 2/3 traffic.
• The ability to filter packets at wirespeed
based on MAC addresses, IP
addresses, TCP or UDP ports, or a
combination of these (N-tuple).
• The ability to perform prioritization
based on QoS marking.
• The ability to police traffic based on
user-defined rate limits.
• The ability to handle Head-of-Line
blocking (HOL).
• Wire speed multicast performance.
Test methodology example
Following is an example of a test
methodology for a multi-10GE port switch
that supports the following features:
1. Wire-rate Layer 2/3 (for IPv4)
switching with a minimum packet
size of 64 bytes.
2. Switching capacity per slot that
supports total port capacity on line
card.
3. Filtering based on ACLs.
4. QoS handling based on 802.1p or IP
Type of Service (TOS) bits.
5. Priority scheduling based on
weighted round robin (WRR).
6. Traffic shaping.
7. Routing protocols, including
multicast.
The test methodology is broken out into
module- and system-level testing. In the
real world, local switching on the module
occurs; this is the best-case scenario for
switch performance, because there is no
contention for the fabric. The worst-case
scenario is when all traffic entering the
switch must traverse the fabric,
contending for backplane capacity and
causing over-subscription.
Module-level testing
In this scenario, traffic will stay local to the
line card. This means that switching will
occur locally between ports on the same
line card, and minimal traffic will traverse
the backplane.
System-level testing
In this scenario, all of the ingress traffic is
switched to ports on different line cards.
This means that traffic will be contending
for backplane capacity and will determine
how the system handles oversubscription.
It will be set up with partially meshed
traffic patterns, with unique ingress ports
mapped to unique egress ports, and
multiple ingress ports mapped to a single
egress port.
Test methodologies
1. Layer 2 bidirectional throughput and latency
test. This test determines the Device Under
Test’s (DUT’s) maximum Layer 2
forwarding rate without traffic loss as well
as average latency for different packet
sizes. This test is performed full duplex
with traffic transmitting in both directions.
The DUT must perform packet parsing and
Layer 2 address look-ups on the ingress
port and then modify the header before
forwarding the packet on the egress port.
2. Layer 2 throughput, QoS, and latency test.
This test determines the DUT’s maximum
Layer 2 forwarding rate with packet loss
and latency for different packet sizes. The
DUT must perform a Layer 2 address lookup,
check the 802.1p priority bit value on
the ingress port, send it to the designated
queue, and then modify the header before
forwarding the packet on the egress port.
3. Layer 3 (IPv4) performance test with ACL and
latency. This test determines the DUT’s
maximum IPv4 Layer 3 forwarding rate
with packet loss and latency for different
packet sizes. The DUT must perform
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