Theory Of Operation - Chelsio Communications Chelsio T5 Installation And User Manual

Chapter XVII. WD Sniffing and Tracing

1. Theory of Operation

The objective of these utilities (wd_sniffer and wd_tcpdump_trace) is to provide sniffing and
tracing capabilities by making use of T4's hardware features.
Sniffer- Involves targeting specific multicast traffic and sending it directly to user space.
a) Get a Queue (raw QP) idx.
b) Program a filter to redirect specific traffic to the raw QP queue.
Tracer - All tapped traffic is forwarded to user space and also pushed back on the wire via
the internal loop back mechanism
a) Get a Queue (raw QP) idx
b) Set the T4 adapter in loop back
c) Connect Client A and B to ports 0 and 1 or ports 2 and 3.
d) Enable tracing.
In either mode the targeted traffic bypasses the kernel TCP/IP stack and is delivered directly to
user space by means of an RX queue.
Chelsio T5/T4 Unified Wire For Linux
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