Cisco Cisco FirePOWER Appliance 7020
6-58
FireSIGHT System User Guide
Chapter 6 Managing Devices
Configuring Interfaces
Step 8
In the
MTU
field, type a maximum transmission unit (MTU), which designates the largest size packet
allowed.
The range within which you can set the MTU can vary depending on the FireSIGHT System device
model and the interface type. See
model and the interface type. See
information.
Step 9
Click
Save
.
Your changes are saved. Note that your changes do not take effect until you apply the device
configuration; see
configuration; see
for more information.
Configuring the Interface MTU
License:
Any
When you change the maximum transmission unit (MTU) on an interface or inline set, the following
capabilities may be affected:
capabilities may be affected:
•
traffic inspection, including application awareness and control, URL filtering, intrusion detection
and prevention, and connection logging
and prevention, and connection logging
•
traffic flow, including switching, routing, and related functionality
•
link state
The manner and duration of network traffic interruption depends on the interface type and how your
devices are configured and deployed.
devices are configured and deployed.
Note also that for Sourcefire Software for X-Series, you configure the interface MTU using the
Sourcefire Software for X-Series CLI. See the Sourcefire Software for X-Series Installation Guide for
more information.
Sourcefire Software for X-Series CLI. See the Sourcefire Software for X-Series Installation Guide for
more information.
Note
Because the system automatically trims 18 bytes from the configured MTU value, any value below 1298
does not comply with the minimum IPv6 MTU setting of 1280, and any value below 594 does not comply
with the minimum IPv4 MTU setting of 576. For example, the system automatically trims a configured
value of
does not comply with the minimum IPv6 MTU setting of 1280, and any value below 594 does not comply
with the minimum IPv4 MTU setting of 576. For example, the system automatically trims a configured
value of
576
to
558
.
The following table lists MTU configuration ranges for managed devices.
Managing Cisco ASA with FirePOWER Services Interfaces
License:
Control, Protection
Table 6-7
MTU Range by Device
On this Model Device...
The MTU Range is...
Series 2, except 3D6500, 3D9900
576-1518 (all interfaces, inline sets)
3D6500, 3D9900, virtual
576-9018 (all interfaces, inline sets)
Series 3
576-9234 (management interface)
576-10172 (inline sets)
576-9922 (all others)