Cisco NM-8B-U User Guide - Page 41

Stacking, Flow Control, Using Flow-Control Keywords

Page 41 highlights

16- and 36-Port Ethernet Switch Module for Cisco 2600 Series, Cisco 3600 Series, and Cisco 3700 Series Feature Overview Default Switch Configuration By default, the Ethernet switch network module provides the following settings with respect to Cisco AVVID: • All switch ports are in access VLAN 1. • All switch ports are static access ports, not 802.1Q trunk ports. • Default voice VLAN is not configured on the switch. • Inline power is automatically supplied on the 10/100 ports. Stacking Layer 2 switching may be extended in the router by connecting the Gigabit Ethernet (GE) ports of the Ethernet switch network module. This connection sustains a line-rate traffic similar to the switch fabric found in Cisco Catalyst switches and forms a single VLAN consisting of all ports in multiple Ethernet switch network modules. • MAC address entries learned via intrachassis stacking are not displayed. • Link status of intrachassis stacked ports are filtered. Flow Control Flow-control is a feature that Gigabit Ethernet ports use to inhibit the transmission of incoming packets. If a buffer on a Gigabit Ethernet port runs out of space, the port transmits a special packet that requests remote ports to delay sending packets for a period of time. This special packet is called a pause frame. Using Flow-Control Keywords Table 9 describes guidelines for using different configurations of the send and receive keywords with the set port flowcontrol command. Table 9 Gigabit Ethernet Flow-Control Keyword Functions Configuration send on send off send desired receive on receive off receive desired Description Enables a local port to send pause frames to a remote port. Use send on when a remote port is set to receive on or receive desired. Prevents a local port from sending pause frames to a remote port. Use send off when a remote port is set to receive off or receive desired. Indicates preference to send pause frames, but autonegotiates flow control. You can use send desired when a remote port is set to receive on, receive off, or receive desired. Enables a local port to process pause frames that a remote port sends. Use receive on when a remote port is set to send on or send desired. Prevents a local port from processing pause frames. Use receive off when a remote port is set to send off or send desired. Indicates preference to process pause frames, but autonegotiates flow control. You can use receive desired when a remote port is set to send on, send off, or send desired. Cisco IOS Release 12.2(2)XT, 12.2(8)T, and 12.2(15)ZJ 41

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16- and 36-Port Ethernet Switch Module for Cisco 2600 Series, Cisco 3600 Series, and Cisco 3700 Series
Feature Overview
41
Cisco IOS Release 12.2(2)XT, 12.2(8)T, and 12.2(15)ZJ
Default Switch Configuration
By default, the Ethernet switch network module provides the following settings with respect to
Cisco AVVID:
All switch ports are in access VLAN 1.
All switch ports are static access ports, not 802.1Q trunk ports.
Default voice VLAN is not configured on the switch.
Inline power is automatically supplied on the 10/100 ports.
Stacking
Layer 2 switching may be extended in the router by connecting the Gigabit Ethernet (GE) ports of the
Ethernet switch network module. This connection sustains a line-rate traffic similar to the switch fabric
found in Cisco Catalyst switches and forms a single VLAN consisting of all ports in multiple Ethernet
switch network modules.
MAC address entries learned via intrachassis stacking are not displayed.
Link status of intrachassis stacked ports are filtered.
Flow Control
Flow-control is a feature that Gigabit Ethernet ports use to inhibit the transmission of incoming packets.
If a buffer on a Gigabit Ethernet port runs out of space, the port transmits a special packet that requests
remote ports to delay sending packets for a period of time. This special packet is called a
pause frame
.
Using Flow-Control Keywords
Table 9
describes guidelines for using different configurations of the
send
and
receive
keywords with
the
set port flowcontrol
command.
Table 9
Gigabit Ethernet Flow-Control Keyword Functions
Configuration
Description
send on
Enables a local port to send pause frames to a remote port. Use
send on
when a remote port is set to
receive on
or
receive desired
.
send off
Prevents a local port from sending pause frames to a remote port. Use
send off
when a remote port is set to
receive off
or
receive desired
.
send desired
Indicates preference to send pause frames, but autonegotiates flow
control. You can use
send desired
when a remote port is set to
receive on
,
receive off
, or
receive desired
.
receive on
Enables a local port to process pause frames that a remote port sends. Use
receive on
when a remote port is set to
send on
or
send desired
.
receive off
Prevents a local port from processing pause frames. Use
receive off
when
a remote port is set to
send off
or
send desired
.
receive desired
Indicates preference to process pause frames, but autonegotiates flow
control.
You can use
receive desired
when
a remote port is set to
send
on
,
send
off
, or
send
desired
.