Cisco MDS 9000 Series Troubleshooting Manual page 54

Troubleshooting E Port Connectivity - ISL Isolation
S e n d c o m m e n t s t o m d s f e e d b a c k - d o c @ c i s c o . c o m .
switch# sh fcdomain domain-list vsan 1
Number of domains: 2
Domain ID
---------
0x4a(74)
0x4b(75)
------- -----------------------
The output shown is representative of a simple two switches fabric.
If a domain is currently isolated due to domain overlap, and you later enable the auto-reconfigure option
on both switches, the fabric continues to be isolated. However, if you enable the auto-reconfigure option
on both switches before connecting the fabric, a disruptive reconfiguration (RCF) occurs. The RCF
functionality would automatically force a new principal switch selection and cause new domain ID to be
assigned to the different switches. A disruptive reconfiguration may affect data traffic.
To enable the auto-reconfigure option on a particular VSAN use the following command:
switch(config)# fcdomain auto-reconfigure vsan 10
There are different ways of resolving this issue. One possible solution is to cause an RCF in the fabric
with a disruptive restart of the domain manager on the switch. The RCF functionality will cause all
switches in both fabrics to empty their domain ID list and select a new principal switch. The overlapping
domain ID would be assigned to which ever switch requests it first from the newly selected principal
switch.
The second switch to request that same domain ID would be assigned a new domain ID. This will only
work if the overlapping domain IDs are not statically defined on the switches. If the domain ID is
statically defined on the switch, then the switch does not accept any other domain ID than the one that
is configured. If its request for the configured domain ID is not granted, it isolates itself from the fabric.
The RCF functionality is disruptive and can cause end nodes to be assigned new domain IDs. By default,
Cisco MDS 9000 Family switches accept disruptive restarts. You can configure the switch in order to
reject incoming RCFs on a per-VSAN and port level basis (enabling the rcf-reject option).
In case the rcf-reject option is on, in order to have the RCF propagated to the switches in the fabric,
must have the RCF reject property disabled. To turn this option off use the following command:
switch(config-if)# no fcdomain rcf-reject vsan 1
At this point a disruptive restart should be triggered, by using the following command:
switch# config t
Enter configuration commands, one per line. End with CNTL/Z.
switch(config)# fcdomain restart disruptive vsan 1
switch(config)#
When you do a disruptive restart on your switch and the switch on the other side does not have disruptive
restart enabled the error on the E port would be the following
switch# show interface fc2/5
fc2/5 is down (isolation due to invalid fabric reconfiguration)
Hardware is Fibre Channel
Port WWN is 20:45:00:05:30:00:18:a2
Admin port mode is auto, trunk mode is on
Port vsan is 1
Receive data field size is 2112
Cisco MDS 9000 Family Troubleshooting Guide
3-8
Chapter 3
WWN
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20:01:00:05:30:00:13:9f [Local]
20:01:00:05:30:00:13:9e [Principal]
Troubleshooting Switch Level Issues and Interswitch Connectivity
OL-5183-02, Cisco MDS SAN-OS Release 1.3