Руководство По Проектированию для Cisco Cisco Nexus 5010 Switch

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Group Port- Type Protocol Member Ports

Channel

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51 Po51(SU) Eth LACP Eth2/1(P) Eth2/2(D)

Bringing down SVI 50 is desirable, because doing this the traffic from the core destined to VLAN 50 takes the path

via the primary vPC device.

For VLAN 40, the failure of the peer link has the effect that on the secondary vPC device SVI 40 is brought down

because all SVIs for vPC VLANs are brought down, the SVI 40 on primary vpc device will stay up because there is

at least one active vpc (or link) carrying vlan 40.

You can modify this behavior in such a way that the SVI 40 stays up on secondary as well in two possible ways:

●

Using a separate trunk between the Cisco Nexus 7000 devices for non-vPC VLANs and including vlan 40

on that trunk instead of the vpc peer-link

●

Excluding the non-vPC VLANs from the vPC autostate behavior as described in this section

If the desired behavior is to keep VLAN 40 up, because it is not used on any vPC, you should just modify the vPC

domain configuration as follows:

vpc domain 1

role priority 100

dual-active exclude interface-vlan 40

Layer 3 Best Practices

With Cisco NX-OS Software Release 4.2, the HSRP protocol on the Cisco Nexus 7000 Series can support

upgrades to the supervisor without flapping HSRP. This is achieved by incrementing the hold-time value (extended

hold-time) automatically during the upgrade. Apart from this, the user needs to configure nothing special compared

to regular HSRP configurations.

The following list summarizes Layer 3 best practices for vPC configurations:

●

HSRP is configured normally, ideally with primary and secondary roles matching the vPC role priorities.

Preemption should be configured, again mostly to maintain the active configuration as closely as possible to

that specified in the network design.

●

Should a peer link failure occur, the SVIs on the operational secondary will be shut down, which enforces

only one possible active topology: that is, the SVI on the primary Cisco Nexus 7000 Series Switch is going

to be the active HSRP interface. If you want to remove an SVI from this behavior you should use the

command dual-active exclude interface-vlan <non-vPC vlans list> in the vPC domain configuration.

●

Avoid using static routing with HSRP tracking of core links in order to avoid the situation where routed traffic

from access switch to access switch is dropped due to the duplicate prevention technique used by vPC.
See Chapter 3, “L3 Link Between vPC Peers” for more information.

●

Dynamic routing with L3 VLANs or links between aggregation Cisco Nexus 7000 Series devices is

recommended.

●

Routing from the core to the aggregation layer should use Layer 3 links with no vPCs. Traffic distribution is

going to use Equal Cost Multipath (ECMP).