Cisco Cisco Nexus 5010 Switch 디자인 가이드
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As of Cisco NX-OS 5.0(2)N1(1), the Cisco Nexus 5000 Series supports 12,000 logical interfaces with a maximum
of 4000 network ports (that is, ports that are not spanning-tree port type edge).
Cisco NX-OS 5.0(2)N1(1) on the Cisco Nexus 5500 platform supports a maximum of 12,000 logical interfaces in
any combination.
As of Cisco NX-OS 5.0(3)N1(1a), the Cisco Nexus 5500 platform supports a maximum of 14,500 logical interfaces.
As of Cisco NX-OS 5.1(3)N1(1) the Cisco Nexus 5500 platform supports a maximum of 32,000 logical interfaces
but 16,000 have been verified. In a future release, the code will be verified in order to provide full support for
32,000 logical interfaces.
To increase the scalability of spanning tree in the presence of deployments with a large number of VLANs, you can
configure lacp suspend individual on PortChannels to help ensure that if the PortChannel unbundles, the ports are
put in the suspended state instead of the individual state.
Unidirectional Link Detection
The Unidirectional Link Detection (UDLD) Protocol is described in the Cisco configuration guide as follows:
“The
Cisco-proprietary Unidirectional Link Detection (UDLD) protocol allows ports that are connected through fiber
optics or copper (for example, Category 5 cabling) Ethernet cables to monitor the physical configuration of the
cables and detect when a unidirectional link exists. When the switch detects a unidirectional link, UDLD shuts down
the affected LAN port and alerts the user. Unidirectional links can cause a variety of problems, including spanning
tree topology loops
”.
This guide can be found at the following link:
In Cisco NX-OS, UDLD must be explicitly enabled as a feature and also enabled on a per interface basis:
interface Ethernet1/19
switchport mode trunk
switchport trunk allowed vlan 50,60,100
udld enable
channel-group 21 mode passive
UDLD probes originate at varying intervals depending on the specific state of the UDLD link (Figure 6). On a
bidirectional link with steady state, probes are generated at 15-second intervals by default.
If probes do not arrive because a link became unidirectional, resynchronization is required.
Each port has a cache that expires the hold time (Hold time = 2.5 x Message interval). When the hold time expires,
the port tries resynchronization, and if resynchronization fails, the port is shut down.