DELL N3000 Manual Do Utilizador

Configuring Link Aggregation

In the scenario shown in Figure 28-15(similar to the previous scenario), the 

downstream router is not configured with port-channel and uses ECMP or 

some other load sharing scheme to send packets to routed MLAG peers. 

MLAG cannot react appropriately to a link failure on the upstream router 

because the VLANs are routed across the MLAG peers. MLAG cannot 

logically connect the failure on VLAN 30 with orphan VLAN 20. 

Consequently, MLAG does not unblock VLAN 20 from traversing the peer 

link. The downstream router continues to send packets on VLAN 20 to the 

MLAG peer with the failed link. But because routed VLAN 20 is not part of 

the MLAG, packets remain blocked when transiting the MLAG peer link. L3 

routed VLANs termination on the MLAG peers is not supported—VLANs 

must extend across the MLAG peers.

In a “one-armed” topology, the MLAG is partnered with a single router or 

switch. The router is configured with a LAG toward the MLAG peer switches 

and has an IP address configured on the router LAG. The peer switches may 

be configured with VRRP and have IP addresses assigned to both the routed 

VLANs. If a multi-tier MLAG topology is used below the MLAG peers, these 

switches must not have L3 port-channels configured as part of the MLAG. An 

additional backup routed link between the MLAG peers is required to handle 

Peer-Link

MLAG

VLAN 30

Failed Link

VLAN 20