Allied Telesis x908, X900-12XT/S manual Making filters by using QoS class-maps

Making filters by using QoS class-maps

Making filters by using QoS class-maps

QoS class-maps allow you to match on a much wider range of packet attributes than ACLs by themselves. They do this by determining the match criteria from an ACL, or from match commands, or from both in combination. Also, they use an ACL to decide what action to take on a packet, unless you want the default action of permit.

The following figure summarises the class-map logic flow. Note that a class-map with no match commands (including no ACL match) matches on all traffic and forwards it. You could use such a class-map to apply QoS policing to a port, but would not be likely to use it when filtering.

				Start
			yes	Match	no
				on ACL?
		Also				Instead
yes	match on other		no		yes	match on other	no
		things?				things?
Get criteria by					Get criteria by
ANDing together		Get criteria by			ANDing together		Match all
ACL and other		using ACL settings			other match		packets
match commands					commands
	Apply action from ACL				Apply default action
	(permit, deny, send-to-mirror,
						(permit)
	send-to-cpu, copy-to-cpu)
							qos-match.eps

Therefore, the basic procedure for using a class-map as a filter is:

1.Make an ACL to match on MAC address or IP settings, and to specify the action that QoS will take on traffic that matches the class-map.

You need an ACL to specify the action—unless the action is permit—even if you don’t want to match on MAC address or IP settings. In that case, make an ACL with the desired action and with both source and destination address of any. For example, if you want to deny traffic from one VLAN ID, you need an ACL with action of deny and addresses of any.

2.Create the class-map (see page 9).

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