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Appendix E. Configuring network switches
General networking notes
When setting up switches in the 512 mode or any time there intentionally are
multiple connections between switches you must designate one of the core
switches as the spanning tree root. In the case of the 512 node configuration it
must be one of the Cisco Gigabit 4006 switches.
When setting up VLANs on a Cisco Gigabit 4006 running the Cisco Catalyst
operating system (CatOS) make sure to set the vtp domain name. This can be any
name since we are not using vtp to maintain the VLANs.
The Cisco Ethernet 3508/3524 switches only have 1 virtual Ethernet port. This can
be assigned to any VLAN on the switch. Which ever VLAN it is assigned to should
be designated as the Management VLAN for the switch.
The Cisco Gigabit 4006 switch running IOS can have an IP connection for each
VLAN. However the management port on the Supervisor card can only be used for
recovery situations. The number 1 port in the Management VLAN can be dedicated
to hook up the management network to the Cisco Gigabit 4006 switch.
The Cisco Gigabit 4006 switch running the Cisco Catalyst Operating System
(CatOS) has one port that can be used as an Ethernet connection. It is the sc0 port
and can be utilized in any VLAN. The sc0 port must be assigned to the
Management VLAN. Again one port assigned to the Management VLAN needs to
be reserved to make the connection to the switch itself.
Load balancing across EtherChannels is an important performance point. This is
something that would be unique to the jobs that the customer intends to run on the
cluster.
To split networks, creating a primary cluster VLAN and a Management VLAN in the
switches, requires an extra connection between the 3550 and the 3508.
The RJ45 (copper) adapter GBICS must be connected to a Gigabit port or the link
fails. Those GBICS will not negotiate speed.
The Linux kernel by default supports proxy arping. This can cause problems on a
shared media network. If you have more that one NIC in the same broadcast
domain there is a known problem with proxy arping. Proxy arping allows either
interface in the broadcast domain to respond to an arp request. This can cause IP
traffic to be handled by an interface other than the intended one. The only way to
prevent this is to create separate VLANs in the switches.
Switch commands
Use the following section for information on switch commands. Use the command
line interface for executing commands.
Switch commands for the Cisco Catalyst Ethernet 3508/3550 switch
running IOS
These commands will work with a Cisco Gigabit 4006 switch running the Cisco IOS
software platform as well. To set up VLANs, at the command prompt, type:
© Copyright IBM Corp. 2004
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