Brocade Network OS Administrator’s Guide v4.1.1 - Manual (Page 527)

sFlow feature support (Continued) TABLE 87
Feature Brocade VDX 8770 Brocade VDX 67xx
Sample rate calculation Dropped packets (such as errors and
ACL dropped packets) are not
counted for the calculations used for
sample generation Dropped packets (such as errors
and ACL dropped packets) are
counted for the calculations used for
sample generation
Maximum sFlow raw packet header
size 228 bytes
The hardware truncates the packet.
128 bytes
The software truncates the packet.
Flow-based sFlow
Flow-based sFlow is used to analyze a specific type of traffic (flow based on access control lists, or
ACLs). This involves configuring an sFlow policy map and binding it to an interface.
Flow-based sFlow considerations and limitations
The following considerations and limitations for flow-based sFlow should be kept in mind:
• A maximum of 16 profiles is allowed on Brocade VDX 8770 series platforms and 8 on a Brocade
VDX 6740 series platforms.
• The purpose of flow-based sFLow is not to drop or trap packets on the basis of ACLs, but rather just
to match traffic. Packets are still sampled and allowed, and sFlow samples are generated for any
rule.
• Port-based sFlow takes precedence over flow-based sFlow. Both cannot operate simultaneously.
• On Brocade VDX 8770 series platforms, if a packet is classified as a Layer 3 IPv4 packet, with a
match on destination address and IP type, and even if a packet’s destination or source address
matches a Layer 2 ACL, flow-based sFlow samples are not generated. This is not the case with
Brocade VDX 6740 series platforms.
• Because all samples of different rates are sent to the collector from a single port, only the lowest
sampling rate is used.
On Brocade VDX 6740 series platforms, if the traffic is Layer 2 then samples with a MAC ACL sample
rate are collected. If the traffic is Layer 3, then samples with a Layer 3 ACL sample rate are collected.
Configuring the sFlow protocol
Consider the topics discussed below when configuring the sFlow protocol.
Configuring the sFlow protocol globally
Brocade recommends that you globally configure sFlow on the Brocade switch first, and then enable
sFlow on specific interface ports and make custom alterations, because sFlow parameters at the
interface level can differ from those at the global level. For details, refer to
Configuring sFlow for
interfaces on page 528.
Enabling sFlow globally does not enable it on all interface ports. sFlow must be explicitly enabled on all
the required interface ports. Refer to
Enabling and customizing sFlow on specific interfaces on page
529.
Flow-based sFlow
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