broadcast suppression

Posted on 2009-04-16
Last Modified: 2012-05-06
I just recently took over a position as a network admin and we have 8 3com 4500g switches. I was looking at the configs on them and the previous admin had broadcast, multicast and unicast suppression on all the interfaces. i've never worked with them on. What is a good range for them. Do i need all 3 or just broadcast suppression? The current setup is base on PPS and not ratio. What is better pps or ratio? i included one of the ports

interface GigabitEthernet1/0/19
 port access vlan 6
 broadcast-suppression 20
 multicast-suppression 20
 unicast-suppression 20
 undo jumboframe enable
 description ------ PUNCH DOWN PORT 232
 stp edged-port enable
 mac-address max-mac-count 1
Question by:ngaba
    LVL 21

    Expert Comment

    I would say ratio is easier to understand.

    I wonder why anyone would like to limit port's unicast bandwidth to 20 pps. 20 pps is not that much, potentially you may face problems with this setting as all traffic beyond 20 pps will be dropped, so download via udp is hardly possible
    as for multicast - if you are not using multicast at all, then you are not affected by this setting.
    broadcast suppression is ok, unless you don't have problems with that.

    LVL 2

    Author Comment

    So would you suggest removing the unicast one?  what about the 20 pps for multicast and broadcast, is that an acceptable number, or should i go to a ratio based? if so whats a good ratio.
    LVL 21

    Accepted Solution

    you can use ratio instead, but system will use pps anyway (it is by design)

    yes, remove unicast limits
    broadcast should be at a level of 2-3 percent of interface speed
    multicast - if you have norton ghost or live video, then just remove limitation, if you don't use multicast, configure limit the as for broadcasts.

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