Zyxel XS3700-24 [60/371] Hapter

Zyxel XS3700-24 [60/371] Hapter
Ethernet Switch CLI Reference Guide
60
CHAPTER 14
Data Center Bridging
Commands
At the time of writing, data center bridging can only be configured using commands on the
Switch.
14.1 Overview
A traditional Ethernet network is best-effort, that is, frames may be dropped due to network
congestion. FCoE (Fiber Channel over Ethernet) transparently encapsulates fiber channel
traffic into Ethernet, so that you don’t need separate fiber channel and Ethernet switches.
Data Center Bridging (DCB) enhances Ethernet technology to adapt to the FCoE. It supports
lossless Ethernet traffic (no frames discarded when there is network congestion) and can
allocate bandwidth for different traffic classes, based on IEEE802.1p priority with a
guaranteed minimum bandwidth. LAN traffic (large number of flows and not latency-
sensitive), SAN traffic (Storage Area Network, large packet sizes and requires lossless
performance), and IPC traffic (Inter-Process Communication, latency-sensitive messages) can
share the same physical connection while still having their own priority and guaranteed
minimum bandwidth.
You should configure DCB on any port that has both Ethernet and fiber channel traffic.
14.1.1 PFC, ETS, and DCBX Standards
DCB may use PFC, ETS, application priority and DCBX to adapt to the FCoE.
PFC (Priority-based Flow Control, IEEE 802.1Qbb -2011) is a flow control mechanism
that uses a PAUSE frame to suspend traffic of a certain priority rather than drop it when
there is network congestion (lossless). If an outgoing (egress) port buffer is almost full, the
Switch transmits a PAUSE frame to the sender who just transmitted traffic requesting it to
stop sending traffic of a certain priority to that port. For example, say outgoing port 8 is
receiving too much traffic of priorities 3-6 from port 1. Then if port 1 is configured with
PFC priorities 3-6, port 1 can request the sender to suspend traffic with priorities 3-6.
Similarly, if the outgoing (egress) port 8 receives a PAUSE frame with PFC priorities 0-1,
then if port 8 is configured with PFC, it can suspend sending traffic with PFC priorities 0-
1.
ETS (Enhanced Transmission Selection, IEEE 802.1Qaz -2011) is used to allocate
bandwidth for different traffic classes, based on IEEE802.1p priority (0 to 7, allowing for
eight types of traffic) with a guaranteed minimum bandwidth.

Содержание

Скачать