Configuring inbound rate-limiting for broadcast and multicast traffic

You can configure rate-limiting (throttling) of inbound broadcast and multicast traffic on the switch, which helps prevent the switch from being disrupted by traffic storms if they occur on the rate-limited port. The rate-limiting is implemented as a percentage of the total available bandwidth on the port.

The rate-limit command can be executed from the global or interface context, for Example:

switch(config)# interface 3 rate-limit bcast in percent 10

or

switch(config)# interface 3
switch(eth-3)# rate-limit bcast in percent 10

Syntax:


rate-limit {< bcast | mcast >} in percent < 0-100 > 

Option

in percent <0-100>
Also supports configuring limit in kbps

[no] rate-limit {<bcast | [mcast >]} in

Enables rate-limiting and sets limits for the specified inbound broadcast or multicast traffic. Only the amount of traffic specified by the percent is forwarded.

Default: Disabled

If you want to set a limit of 50% on inbound broadcast traffic for port 3, you can first enter interface context for port 3 and then execute the rate-limit command, as shown in Inbound broadcast rate-limiting of 50% on port 3. Only 50% of the inbound broadcast traffic will be forwarded.

Inbound broadcast rate-limiting of 50% on port 3

switch(config)# int 3
switch(eth-3)# rate-limit bcast in percent 50

switch(eth-3)# show rate-limit bcast
 Broadcast-Traffic Rate Limit Maximum %

  Port  | Inbound Limit Mode      Radius Override
  ----- + ------------- --------- ---------------
  1     | Disabled      Disabled  No-override
  2     | Disabled      Disabled  No-override
  3     | Disabled      %         No-override
  4     | Disabled      Disabled  No-override
  5     | Disabled      Disabled  No-override

If you rate-limit multicast traffic on the same port, the multicast limit is also in effect for that port, as shown in Inbound multicast rate-limiting of 20% on port 3. Only 20% of the multicast traffic will be forwarded.

Inbound multicast rate-limiting of 20% on port 3

switch(eth-3)# rate-limit mcast in percent 20
switch(eth-3)# show rate-limit mcast
 
 Multicast-Traffic Rate Limit Maximum %

  Port  | Inbound Limit Mode      Radius Override
  ----- + ------------- --------- ---------------
  1     | Disabled      Disabled  No-override
  2     | Disabled      Disabled  No-override
  3     | 20            %         No-override
  4     | Disabled      Disabled  No-override

To disable rate-limiting for a port enter the no form of the command, as shown in Disabling inbound multicast rate-limiting for port 3.

Disabling inbound multicast rate-limiting for port 3

switch(eth-3)# no rate-limit mcast in

switch(eth-3)# show rate-limit mcast
 
 Multicast-Traffic Rate Limit Maximum %

  Port  | Inbound Limit Mode      Radius Override
  ----- + ------------- --------- ---------------
  1     | Disabled      Disabled  No-override
  2     | Disabled      Disabled  No-override
  3     | Disabled      Disabled  No-override
  4     | Disabled      Disabled  No-override