Table Of Contents
Release Notes for Catalyst 4840G SLB Switch for Cisco IOS Release 12.0(11.5)WX5(18)
Determining the Software Version
Feature Set for the Catalyst 4840G SLB Switch
Features Not Supported on the Catalyst 4840G SLB Switch
Open Caveats - Release 12.0(11.5)WX5(18)
Resolved Caveats - Release 12.0(11.5)WX5(18)
Obtaining Technical Assistance
Release Notes for Catalyst 4840G SLB Switch for Cisco IOS Release 12.0(11.5)WX5(18)
October 6, 2000
This document provides the software features for the current Catalyst 4840G server load balancing (SLB) switch and caveats for Cisco IOS Release 12.0(11.5)WX5(18).
Contents
This publication includes the following sections:
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Determining the Software Version
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Introduction
The Catalyst 4840G SLB switch is a high-performance SLB Layer 3 switch.
SLB and Layer 3 switching refers to a class of high performance switches optimized for the campus LAN or intranet, providing both wire speed Ethernet routing and switching services as well as SLB.
SLB handles the increasing number of visitors and amount of data on your enterprise web servers. These web servers must provide secure and reliable Web and application hosting services to your Internet or intranet clients.
The SLB switch redistributes the requests (or hits) from clients evenly among all the servers in the server farm and achieves a balanced load for each server in the farm. In addition, all real servers appear as one virtual server, resulting in the need for only a single IP address and a single URL for an entire server farm.
System Requirements
This section describes the system requirements for the Catalyst 4840G SLB switch for Cisco IOS Release 12.0(11.5)WX5(18).
Memory Requirements
The standard default memory for the Catalyst 4840G SLB switch is 128 MB of SDRAM and 16 MB of onboard Flash memory. No Flash PC card is installed by default. In a future software release, the SLB switch will be able to accept an optional 8-, 16-, or 20-MB Type II Flash PC card.
Hardware Supported
The Catalyst 4840G SLB switch is a fixed configuration, Layer 3 10/100/1000 Ethernet SLB switch. There are 40 high-density 10/100BASE-T Fast Ethernet and 2 GBIC Gigabit Ethernet interfaces on this SLB switch.
Determining the Software Version
To determine the version of the Cisco IOS software currently running on the Catalyst 4840G SLB switch, log in to the SLB switch and enter the show version EXEC command.
Feature Set for the Catalyst 4840G SLB Switch
Cisco IOS software is packaged in feature sets or software images that vary according to this platform. Table 1 lists the Cisco IOS software feature set available for the Catalyst 4840G SLB switch for Cisco IOS Release 12.0(11.5)WX5(18).
Features Not Supported on the Catalyst 4840G SLB Switch
Table 2 lists the features that are not supported on the Catalyst 4840G SLB switch.
Limitations and Restrictions
The following configuration limitations and restrictions apply to the Catalyst 4840G SLB switch:
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Caveats
The following caveats were introduced on the Catalyst 4840G SLB switch for Cisco IOS Release 12.0(11.5)WX5(18).
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Open Caveats - Release 12.0(11.5)WX5(18)
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The command-line interface (CLI) allows you to configure unsupported ipx, mls rp, and cos commands.
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You cannot ping a virtual server from the SLB switch where the server is configured.
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The first connection to a real server that is attached to a Catalyst 4840G SLB switch through a BVI interface ordinarily will perform slowly due to incomplete ARP caches. The BVI-related ARP cache entry will time out quickly (every 3 or 4 seconds) unless traffic is flowing to the associated real server.
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The client network address for the HTTP probe packets is not translated. If client NAT is configured on a server farm with HTTP probe configured, the transmitted probe packets still have the SLB switch interface IP address as the source IP address.
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The Catalyst 4840G SLB switch does not show up in the firewall load-balancing traceroute path. This is because TTL is not decremented in this nonrouting mode. (The firewall does not do true routing; it load balances based on the route.)
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The connection object on slb-cpu (the loadbalancing processor board), rather than the connection between client and server, is 'stuck ' in ESTABlish state. In other words, the information for these connections in the connection database is not cleaned up.
Workaround: There is a 60 minute timer that will clear this.
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Any packets sent to a virtual server that contains IP options will not load balance.
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If you have SLB DFP connections and then disable IP routing (no IP routing) and DFP (no IP SLB DFP), the switch will hang. You will then need to reboot. Packets sent to a virtual server that contains IP options will not load balance.
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When the Catalyst 4840G SLB switch is deconfigured and the firewall is configured on the switch, the packets that are targeted to the firewall's IP address will not be load balanced.
Workaround: When the SLB configuration is removed and the firewall configuration added, you need to reboot the switch once to avoid this problem.
Resolved Caveats - Release 12.0(11.5)WX5(18)
There are no resolved caveats introduced on the Catalyst 4840G SLB switch for Cisco IOS Release 12.0(11.5)WX5(18).
Additional Documentation
The following documents are available for Catalyst 4000 family switches:
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Obtaining Documentation
World Wide Web
You can access the most current Cisco documentation on the World Wide Web at http://www.cisco.com, http://www-china.cisco.com, or http://www-europe.cisco.com.
Documentation CD-ROM
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Customers and partners can self-register on CCO to obtain additional personalized information and services. Registered users may order products, check on the status of an order and view benefits specific to their relationships with Cisco.
You can access CCO in the following ways:
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You can e-mail questions about using CCO to cco-team@cisco.com.
Technical Assistance Center
The Cisco Technical Assistance Center (TAC) is available to warranty or maintenance contract customers who need technical assistance with a Cisco product that is under warranty or covered by a maintenance contract.
To display the TAC web site that includes links to technical support information and software upgrades and for requesting TAC support, use www.cisco.com/techsupport.
To contact by e-mail, use one of the following:
In North America, TAC can be reached at 800 553-2447 or 408 526-7209. For other telephone numbers and TAC e-mail addresses worldwide, consult the following web site: http://www.cisco.com/warp/public/687/Directory/DirTAC.shtml.
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