Extreme Networks 200 Series - Manual (Page 149)

Summit 200 Series Switches in Multi-ring Topologies
Summit 200 Series Switch Installation and User Guide 147
Summit 200 Series Switches in Multi-ring Topologies
Figure 28 shows how a data VLAN could span two rings having two interconnecting switches in
common.
Figure 28: EAPS data VLAN spanning two rings.
In this example, there is one EAPS domain with its own control VLAN running on the ring labeled LHS
and another EAPS domain with its own control VLAN running on the ring labeled RHS. A data VLAN
that spans both rings acts as a protected VLAN to both EAPS domains. Switches S 5 and S 10 will have
two instances of EAPS domains running on them: one for each ring.
Summit 200 series switches can be deployed in a multi-ring EAPS topology subject to these guidelines:
• Summit 200 series switches can be used as any of the EAPS nodes in the ring except as a node that
interconnects the two rings. For example, in the example shown in Figure 28, nodes S 5 and S 10
cannot be Summit 200 series switches. Summit 200 series switches support EAPS Version 1 (EAPSv1)
and only support a single EAPS domain per switch.
• Depending on the network topology and the versions of EAPS (EAPSv1 vs. EAPSv2) running on the
other EAPS nodes, there might be a requirement to configure STP support for EAPSv1 to prevent
super loops—in the event of a break in the common link between the nodes interconnecting the
rings. On multi-ring topologies, the node interconnecting two rings either needs to be running
EAPSv2 or it must be configured for STP. By having either EAPSv2 or STP on this connecting node,
the Summit 200 has EAPS awareness and correctly recovers in the event of a break in the common
link. For example, in the example shown in Figure 28, a break in the link between nodes S 5 and S 10
would result in a super loop if they were both running EAPSv1 without STP. The following scenarios
demonstrate the different EAPS configurations.
— Case 1: Summit 200 series switches on a single ring. In this case, EAPSv1 requires no STP
support because it is not interconnecting with another ring.
— Case 2: Summit 200 series switches on a multi-ring network along with ring-connecting
switches not running EAPSv2. In this case, the Summit 200 series switches still cannot be
ring-connecting nodes, and this implementation requires configuring EAPSv1 plus STP support to
prevent super loops. This configuration process is described in the EAPS chapter of the
ExtremeWare Software User Guide, Version 7.1.0.
— Case 3: Summit 200 series switches on a multi-ring network along with ring-connecting
switches running EAPSv2. In this case, the Summit 200 series switches still cannot be
LC24015
S 4
S 3
S 2
S 7
S 8
S 6
S 5
(STP root)
S 10 S 1
Master
node
Master
node
S 9
LHS ring RHS ring
P S S P
1 2 3
1 2 3
4 5
4 5