Specifications

182 ExtremeWare XOS 11.0 Concepts Guide
Ethernet Automatic Protection Switching
Figure 15: Multiple EAPS domains sharing common link
You add the VLANs carrying the STP BPDUs to the EAPS master node as a protected VLAN. When
everything is normal and the common link is up, the STP BPDUs are blocked by the EAPS master
nodes. The STP domains on both the core switches have their ports in the forwarding state.
When the common link goes down, the EAPS master ports immediately move into “failed” state and
open the secondary port. In the next STP hello interval, the root sends its BPDUs. At this time, the
BPDUs pass through the EAPS secondary port, and the designated bridge receives the BPDUs on both
ports. STP blocks one of these ports and breaks the loop.
You may experience a brief temporary loop (up to about 2 seconds) in the network. This period is the
time between when EAPS opens the secondary ports and the STP root sends out the periodic BPDU.
For information on using EAPS and EMISTP or STP 802.D mode to avoid this situation, see
“Configuring EAPS with STP” on page 190.
Configuring EAPS on a Switch
To configure and enable an EAPS domain, complete the following steps:
1 Create EAPS domain and assign the name.
2 Configure the control VLAN.
3 Configure the protected VLAN(s).
4 Add the control VLAN to EAPS domain.
5 Add the protected VLAN(s) to EAPS domain.
6 Configure EAPS mode, master or transit.
7 Configure EAPS port, secondary and primary.
8 If desired, configure timeout and action for failtimer expiration*.
9 If desired, configure the hello time for the health-check packets*.
EW_091
Master
node
S 4
S 3
S 2
S 1
S
123
45
45
213
P
LHS ring
S 7
S 8
S 9
S 6
S
5
(STP root)
S 10
Master
node
PS
RHS ring