Nortel Networks NN47200-503 Management Vlan, Layer 2 versus Layer 3 mode, Routing and management

20An Introduction to IP Routing Protocols

Management VLAN

Prior to Software Release 4.0, the Management VLAN was the only VLAN that was used to carry the management traffic, including Telnet, Web, SNMP, BootP and TFTP for the switch. The Management VLAN always exists on the switch and cannot be removed. All IP settings, including switch IP address, stack IP address, subnet mask and default gateway, apply only to the Management VLAN.

In this release of Nortel Ethernet Routing Switch 5500 Series, a regular Layer 2 (L2) VLAN behaves like a routable L3 VLAN if a pair of IP addresses and a MAC address are attached to the VLAN. When routing is enabled in L3 mode, every L3 VLAN is capable of doing routing as well as carrying the management traffic. Any L3 VLAN can be used instead of the Management VLAN to manage the switch.

Layer 2 versus Layer 3 mode

When the Nortel Ethernet Routing Switch 5500 Series is configured to route IP traffic between different VLANs, the switch is considered to be running in L3 mode; otherwise, the switch runs in L2 mode.

The L3 manager determines in which mode a switch or a stack should be run. The mode is determined based on the user settings and events. But the general rule is to select:

•L3 mode: if routing is turned on globally for the switch or stack.

•L2 mode: if routing is turned off globally for the switch or stack.

Routing and management

In L3 mode, the Management VLAN, as well as all other L3 VLANs, has the capability to route and carry the management traffic. In this release of the Nortel Ethernet Routing Switch 5500 Series, the settings apply to all L3 VLANs or only to the Management VLAN. "VLAN settings" (page 20)shows all possible settings and default settings for each type of VLAN.

VLAN settings

VLAN/Feature	Routing	Management	Default Route
	(default)	(Routing)
Management VLAN	Off	On	Yes (Management
(L2 mode)			VLAN only)
Management VLAN	On/off (on)	On	No
(L3 mode)
L3 VLAN	On/off (on)	On/off (on)	Yes (global)

Setting IP routing

To set IP routing (or L3 VLANs), take the following steps:

Nortel Ethernet Routing Switch 5500 Series

Configuration-IP Routing Protocols

NN47200-503 03.01 Standard

5.127 August 2007

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