Lag And Master Port; Lag And Port Redundancy; Lag And Multiple Switches; Multiple Switches With L2 Redundancy - Cisco ASR 5500 Administration Manual

System Settings

LAG and Master Port

Logical port configurations (VLAN and binding) are defined in the master port of the LAG. If the master port
is removed because of a card removal/failure, another member port becomes the master port (resulting in VPN
binding change and outage), unless there is a redundant master port available.
Important

LAG and Port Redundancy

ASR 5500 LAG implementation assumes that:
• LAG ports on MIO/UMIO-slot 5 and MIO/UMIO-slot 6 are connected to two Ethernet switches.
• LAG ports on MIO/UMIO-slot 5 and MIO/UMIO-slot 6 are both active at the same time.
• Ports on MIO/UMIO-slot 5 and MIO/UMIO-slot 6 are redundant with each other.
All ports in a LAG can be auto-switched to another MIO/UMIO when certain active port counts or bandwidth
thresholds are crossed.

LAG and Multiple Switches

This feature connects subscriber traffic ports on MIOs to ports on Ethernet switches. A port failure/switch
forces all ports in a LAG to switch to the other MIO/UMIO when a specified threshold is crossed. This works
in a way similar to the auto-switch feature for port redundancy. LACP runs between the ASR 5500 and the
Ethernet switch, exchanging relevant pieces on information, such as health status.
The following table summarizes typical LAG functionality on an MIO/UMIO card.
Table 4: MIO/UMIO LAG Functionality
ASR 5500
MIO/UMIO Port 11
MIO/UMIO Port 12
MIO/UMIO Port 13

Multiple Switches with L2 Redundancy

To handle the implementation of LACP without requiring standby ports to pass LACP packets, two separate
instances of LACP are started on redundant cards. The two LACP instances and port link state are monitored
to determine whether to initiate an auto-switch (including automatic L2 port switch).
The master port on which VLAN can be created for VPN binding must always be configured on the
active/master MIO/UMIO. The redundancy between the MIO/UMIO in slot 5 and the MIO/UMIO in slot
6 automatically causes both ports to be the master with the same VLANs configured and active.
LAGID Ethernet Switch A
1 Port 1
1 Port 2
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ASR 5500 System Administration Guide, StarOS Release 19
LAG and Master Port
Ethernet Switch B
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Port 1
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