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Control Hardware

Setting up Nortel Switches

This document describes setting up a Nortel 5500-series switch as an experimental switch.

The Emulab snmpit support works for at least the Nortel 5500 series switches; at DETER, we use 5510-48Ts and 5530-24Ts. Keith Sklower of UCB wrote the actual code, and can provide suggestions about which other Nortel switches will work with the snmpit code.

There are at least two different lines of switches with different SNMP MIBs, so there are definitely some Nortel switches which will NOT work. The switches that use the RAPID-CITY mib should be okay, including the 8000-series switches, although they have not been tested. Apparently, *none* of the Nortel switches that are provided as part of IBM blade centers will work with the current code; if you're interested in support, definitely contact Keith.

All of these commands are supposed to be typed from the command line (use the "Command Line Interface" menu option). Make sure that you go into "config term" mode to make the changes. We usually leave our switches configured to come up with the menu, as there are some common functions that are much easier to do from the menu.

Access to the switches

At DETER, we've had the switches lock up infrequently. When they lock up, they require a power cycle to come back, and often have managed to lose all or part of their configuration.

For this reason, we have permanent connections to the serial ports on the switches from serial port servers, so that we can get in and reset the configuration by hand. We also have the switches on power controllers, so that we can power off the switches remotely.


While I've set up Nortels at DETER several times, and they seem to work just fine, I may have forgotten some of the details in my rush to get things working. Here are my suggestions -- please let me know what details I've forgotten!

You can ask us at DETER for our 300KB+ Nortel configuration files; for obvious reasons, we don't include them here. Oh, yeah, and we're running SW v4.2.1.005.

ToS bits

By default, the Nortels appear to set the *IP* ToS bits to zero for most packets. To prevent this, turn off QoS on the switch altogether. This make sense if we want the network to appear as though the switch is a direct connection:

no qos if-assign port ALL

Spanning tree

I believe that both Keith and I just turned off STP via the menu options, but from the command line it should go something like this (YMMV):

interface FastEthernet ALL
spanning-tree port ALL learning disable

Extra packets

As above, we also want to turn off all topology discovery packets, which will otherwise interfere with idle detection:

no autotopology

IGMP packets

Make sure that multicast can be flooded around the switch correctly; the Nortel documentation for this command is particularly cryptic, but it works for us. Doing IGMP snooping apparently (as per Keith) locked up our switches. Ugh

vlan igmp unknown-mcast-no-flood disable

MAC address aging

While we don't have this set at DETER right now, Keith recommended turning off mac address aging, as per the various Cisco setup suggestions. The Nortel maximum (as per Keith) is apparently a million; there is no way to turn it off altogether.

mac-address-table aging-time 1000000