Saturday, 7 July 2012

Configuring PowerConnect and Cisco Switches for iSCSI SANs


The below are extracts taken from the pdf “Dell EqualLogic Configuration Guide – A guide to building an iSCSI based SAN solution with Dell EqualLogic PS Series Arrays.” This is nice information to have to hand when in the field. The document is for EqualLogic but is applicable to most iSCSI SAN solutions.

General Requirements for Switches When Used with EqualLogic PS Series Arrays

> Non-Blocking backplane design
> Support for Inter-Switch Linking (ISL) or Dedicated Stacking Architecture
> Support for creating Link Aggregation Groups (LAG)
> Support for active or passive Flow Control (802.3x) on ALL ports
> Support for Rapid Spanning Tree Protocol (R-STP)
> Support for Jumbo Frames
> Ability to disable Unicast Storm Control
> Adequate Buffer Space per switch port

PowerConnect 54xx Switch Configuration – CLI Commands

To enter privileged mode:
switch> enable

To enter configuration mode:
switch# configure

To exit configuration mode (and any level), save running-config to startup-config (IMPORTANT), then exit priviledged mode:
switch(config)# exit
switch# copy running-config startup-config
switch# exit

To configure Port 10:
switch(config)# interface ethernet g10

To configure all ports g1 to g15:
switch(config)# interface range ethernet g(1-15)

To disable iSCSI optimization setting (QoS for iSCSI frames to have priority – designed to optimize an iSCSI storage solution consisting of just a single device, and not optimal for a SAN of multiple arrays):
switch(config)# no iscsi enable

Enabling the PortFast Option to Configure STP Edge Ports:
switch(config)# spanning-tree mode rstp
switch(config)# interface ethernet g10
switch(config-if)# spanning-tree portfast

Configuring Flow Control (and speed and duplex settings):
switch(config)# interface range ethernet g(1-48)
switch(config-if)# speed 1000
switch(config-if)# duplex full
switch(config-if)# flowcontrol on

Disabling port storm control on one port:
switch(config)# interface ethernet g1
switch(config-if)# no port storm-control broadcast enable

Disabling port storm control on all ports:
switch(config)# interface range ethernet all
switch(config-if)# no port storm-control broadcast enable

Enabling Jumbo Frames (on all ports):
switch(config)# port jumbo-frame

PowerConnect 62xx Switch Configuration – CLI Commands
Note the different naming convention!

Enabling the PortFast Option to Configure STP Edge Ports:
switch(config)# spanning-tree mode rstp
switch(config)# interface ethernet 1/g10
switch(config-if)# spanning-tree portfast

Configuring Flow Control – enabling on all ports:
switch(config)# flowcontrol

Disabling port storm control:
switch(config)# interface ethernet 3/g10
switch(config-if)# no storm-control unicast

Disabling port storm control on all ports:
switch(config)# interface range ethernet all
switch(config-if)# no storm-control unicast

Enabling Jumbo Frames (on all ports):
switch(config)# interface range ethernet all
switch(config-if)# mtu 9216

Cisco IOS Based Switch Configuration – CLI Commands

Enabling privileged mode and entering configuration mode:
CiscoSW> enable
CiscoSW# configure terminal
CiscoSW(config)#

Enabling the PortFast Option to Configure STP Edge Ports:
CiscoSW(config)# interface gi1/0/1
CiscoSW(config-if)# spanning-tree portfast

Enabling the PortFast Option globally:
CiscoSW(config)# spanning-tree portfast default

Configuring Flow Control:
CiscoSW(config)# interface gigabitethernet1/0/1
CiscoSW(config-if)# flowcontrol receive desired

Disabling Unicast Storm Control:
CiscoSW(config)# interface gigabitethernet1/0/15
CiscoSW(config-if)# no storm-control unicast level

Enabling Jumbo Frames (requires switch reload):
CiscoSW(config)# system mtu jumbo 9000
CiscoSW(config)# exit
CiscoSW(config)# copy running-config startup-config
CiscoSW(config)# reload

next to enable an individual VLAN to use Jumbo Frames (Note – VLAN1 cannot have Jumbo Frames enabled):
CiscoSW# vlan database
CiscoSW(vlan)# vlan 2 mtu 9000

3 comments:

  1. Thanks for the post.
    We also have a mixed Cisco/Dell environment.
    I was pondering on the jumbo frame mtu size mismatch. Is there any issue with having the larger mtu size on the Dell or are there issues in manually setting the Dell to 9000?

    ReplyDelete
    Replies
    1. Hi James,

      Thank you for the comment.

      It absolutely doesn't matter if the MTU size on the switches is larger than the MTU set on the endpoints (hosts, SAN, ....)

      An example:
      An endpoint sends a packet of MTU 1500 say, via a switch on 9000, the packet stays at 1500 all the way. But if an endpoint sends a packet of MTU 9000 say, via a switch on 1500, the packet has to be fragmented which seriously slows things down.

      I'm pretty certain that the Cisco MTU 9000 and PowerConnect MTU 9216 is the same thing, just measured differently (but might be wrong, so don't take my word for it.)

      Cheers!

      vCosonok

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  2. Great Job!!!
    This post is very wonderful. your steps is really helpful. i like this post and i feel very happy to read this article...
    thanks for sharing...
    more info:- Cisco Router Support



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