Link Aggregation Interoperability of the Dell™ PowerConnect™ 5316M with Cisco IOS or Cisco CatOS based Switches By Bruce Holmes August 2005
Contents Introduction................................................................................................................................................3 Link Aggregation with Gigabit Ethernet Cisco Switches..................................................................5 Configuring the PowerConnect 5316M external ports for Dynamic Link Aggregation...............6 Configuring a Cisco IOS Gigabit Ethernet Switch for Dynamic Link Aggregation.....................
Introduction The Dell PowerConnect 5316M is a fully managed Layer 2 switch that helps organizations reduce the price and cable sprawl traditionally associated with the networking of servers. This robust networking switch is based on the same technology as the PowerConnect 5324, but is housed in a different form factor that is specifically designed for the Dell Modular Server Enclosure.
Dell PowerConnect Cisco IOS/Cat OS Link Aggregation Groups (LAGs) EtherChannel port-channel Channeling channel-group channel-group Fast EtherChannel (FEC) Gigabit EtherChannel (GEC) The primary purpose of LAGs is to increase the overall bandwidth between two switches. This is accomplished by effectively aggregating multiple ports together that act as a single, logical connection between the two switches. The IEEE 802.
If desired, any of the example configurations can be performed on the Dell PowerConnect 5316M via the web based interface (WBI) as well. See the Dell PowerConnect 5316M Ethernet Switch Module Userʹs Guide for a description of the Dell WBI. See the section “Defining LAG Parameters” for information on configuring LAGs via the WBI.
Configuring the PowerConnect 5316M external ports for Dynamic Link Aggregation The following example shows the Dell PowerConnect 5316M Gigabit Ethernet switch commandline interface (CLI) commands for configuring the six external ports on the Gigabit Ethernet switch for LACP.
Configuring a Cisco CatOS Gigabit Ethernet Switch for Dynamic Link Aggregation The following example shows the Cisco CatOS switch CLI commands for configuring six ports for LACP. Cat_6509(enable) set channelprotocol lacp 2 Cat_6509(enable) set port lacp-channel 2/1-6 mode active The first command sets the LAG dynamic protocol to LACP on module 2 (module 2 just happens to be the module that is in the switch used to validate the examples in this paper. Your switch may be configured differently).
Port-channel1 (Primary aggregator) Age of the Port-channel Logical slot/port = 00d:01h:11m:34s = 10/1 Number of ports = 6 HotStandBy port = null Port state = Port-channel Ag-Inuse Protocol = LACP Ports in the Port-channel: Index Load Port EC state No of bits ------+------+------+------------------+----------0 00 Gi1/0/1 Active 0 0 00 Gi1/0/2 Active 0 0 00 Gi1/0/3 Active 0 0 00 Gi1/0/4 Active 0 0 00 Gi1/0/5 Active 0 0 00 Gi1/0/6 Active 0 The output of the command
The output of the command shows the ports 2/1 through 2/6 Status is ‘connected’ and a Channel mode of ‘active’. This confirms that there is physical link on all ports in the LAG and that the Cisco switch has communicated with the PowerConnect 5316M switch to successfully establish an aggregated link on ports 2/1 through 2/6 with LACP.
Cisco CatOS CLI allows the configuration of static LAGs via the LACP or the PAgP CLI commands. Both commands are shown below. The following example shows the Cisco CatOS CLI LACP channelprotocol commands for configuring three ports of the Cisco switch for static link aggregation. Cat_6509(enable) set channelprotocol lacp 2 Cat_6509(enable) set port lacp-channel 2/1-6 mode on The first command sets module 2 to use the LACP commands to configure LAGs.
Cat_6509(enable) show running-config Link aggregation with Cisco Fast Ethernet Switches Some customers have an investment in a Cisco Fast Ethernet (100Mbps) network. In this case the customer may not want to incur the expense to replace their Cisco Fast Ethernet switches to match the highest speed of the Dell PowerConnect 5316M, but they still want to have the most bandwidth possible.
NOTE: This is different from the Cisco IOS and CatOS methods which would require that all the ports in the LAG be configured to 100 Mbps and full duplex rather than setting the LAG to 100Mbps. Configuring all ports in a LAG to 100 Mbps and full duplex on the Dell PowerConnect 5316M would have no effect since the LAG configuration takes precedence. It is important to note this distinction between the Dell CLI and the Cisco IOS and CatOS commands.
CLI will prevent adding internal ports to a LAG To check the configuration of the ports on the Dell PowerConnect 5316M use the ‘show runningconfig’ command and look at the “interface Ethernet gxx” configurations, where the “xx” indicates the port number. In the following example, the “no gvrp enable” command would have to be issued on port g11 before it could be added to a LAG.
Cisco IOS based switches may have the ‘desirable’ and ‘passive’ mode options for the LAG setting. The PowerConnect 5316M does not support this implementation. Do not use the ‘desirable’ or ‘passive’ modes when configuring a LAG with a Dell PowerConnect switch. Only use the ‘active’ (for LACP) or ‘on’ (for static) modes. Switches can only control the distribution of outgoing traffic on LAG ports.
1IOS: Switch *1 Ports 28 Model WS-C3750G-24TS SW Version 12.2(18)SE1 SW Image C3750-I5-M 2CatOS: WS-C6509 Software, Version NmpSW: 7.6(10) Copyright (c) 1995-2004 by Cisco Systems NMP S/W compiled on Oct 27 2004, 17:59:09 THIS WHITE PAPER IS FOR INFORMATIONAL PURPOSES ONLY, AND MAY CONTAIN TYPOGRAPHICAL ERRORS AND TECHNICAL INACCURACIES. THE CONTENT IS PROVIDED AS IS, WITHOUT EXPRESS OR IMPLIED WARRANTIES OF ANY KIND. Dell, PowerEdge, and PowerConnect are trademarks of Dell Inc.
