Avaya 8800 Planning And Engineering, Network Design page 66

Redundant network design
• MLT protection against split VLANs
MLT/LACP groups and port speed
Ensure that all ports that belong to the same MLT/LACP group use the same port speed, for
example, 1 Gbit/s, even if autonegotiation is used. The software does not enforce this requirement.
Avaya recommends that you use CANA to ensure proper speed negotiation in mixed-port type
scenarios.
To maintain LAG stability during failover, use CANA: configure the advertised speed to be the same
for all LACP links. For 10/100/1000 ports, ensure that CANA uses one particular setting, for
example, 1000-full or 100-full. Otherwise, a remote device can restart autonegotiation and the link
can use a different capability.
It is important that each port uses only one speed and duplex mode. This way, all links in Up state
are guaranteed to have the same capabilities. If autonegotiation and CANA are not used, the same
speed and duplex mode settings must be used on all ports of the MLT.
Switch-to-switch MLT link recommendations
Avaya recommends that physical connections in switch-to-switch MLT and link aggregation links be
connected in a specific order. To connect an MLT link between two switches, connect the lower
number port on one switch with the lower number port on the other switch. For example, to establish
an MLT switch-to-switch link between ports 2/8 and 3/1 on switch A with ports 7/4 and 8/1 on switch
B, do the following:
• Connect port 2/8 on switch A to port 7/4 on switch B.
• Connect port 3/1 on switch A to port 8/1 on switch B.
Brouter ports and MLT
In the Avaya Ethernet Routing Switch 8800/8600, brouter ports do not support MLT. Thus, you
cannot use brouter ports to connect two switches with a MLT. An alternative is to use a VLAN. This
configuration option provides a routed VLAN with a single logical port (MLT).
To prevent bridging loops of bridge protocol data units (BPDUs) when you configure this VLAN:
1. Create a new Spanning Tree Group (STGx) for the two switches (switch A and switch B).
2. Add all the ports you would use in the MLT to STGx.
3. Enable the Spanning Tree Protocol (STP) for STGx.
4. On each of the ports in STGx, disable the STP. By disabling STP for each port, you ensure
that all BPDUs are discarded at the ingress port, preventing bridging loops.
5. Create a VLAN on switch A and switch B (VLAN AB) using STGx. Do not add any other
VLANs to STGx; this action can potentially create a loop.
6. Add an IP address to both switches in VLAN AB.
June 2016
on page 67
Planning and Engineering — Network Design
Comments on this document? infodev@avaya.com
66