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Joe Harris, CCIE No. 6200 (R&S, Security & SP) is a Systems Engineer with Cisco Systems® specializing in Security. In addition to authoring Cisco Network Security Little Black Book, Joe has also been a technical reviewer for several Cisco Press publications and written articles, white papers, and presentations on various security technologies. He also assists various Certification Partners by beta testing their newest CCIE certification workbooks and has been recognized by Cisco as an SE Wall of Fame award winner.

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Can the Tx-Ring be modified on the 2800?

June 30th, 2008 • Related • Filed Under

I had a question from a partner related to the Tx-Ring on his customers newly opened 2811 where he would change the Tx-Ring limit however it appeared to him as if it had no effect. So let me explain…Yes, the Tx ring size can be changed with “tx-ring-limit ” interface subcommand but note that the Tx ring itself is not reallocated. It remains 128 entries long. However, once the “tx-ring-limit ” command has been issued, the driver will never put more than of packets on the Tx ring. Because of this it may appear that the tx-ring-limit command is having no effect since it will appear that the tx-ring remains the same size.

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    Comment by Ivan Pepelnjak SLOVENIA Windows XP Internet Explorer 7.0 on 1 July 2008:

    And here’s a longer TX-ring story:

    http://wiki.nil.com/Queuing_Principles_in_Cisco_IOS#Where_to_Queue
    http://wiki.nil.com/Queuing_Principles_in_Cisco_IOS/Tx-ring-limit

    I might have to reword the article … it does not explain all the HW details that I had to figure out from the hardware specs :)