Enterasys Networks X-PeditionTM manual QoS Policy Configuration Examples, Create the policy map

QoS Policy Configuration Examples

Table 12-3 Overhead on IPSec Tunnels

		Tunnel			Total
Tunnel Type	Mode	IP	AH (HMAC)	ESP+3DES
					Overhead
		Header
Tunnel ESP	Tunnel	20 bytes	NA	24 bytes	44 bytes
Tunnel AH	Transport	NA	24 bytes	NA	24 bytes
Tunnel ESP	Transport	NA	NA	24 bytes	24 bytes

As an example, tunnels with ESP and 3DES encoding will add 44 bytes (or more) overhead. Padding for 3DES may add eight more bytes. Calculate the shaper rate with this formula:

ShaperRate = LineRate * ( 1 - OverHead/(OverHead +AvgPktSize))

The table below summarizes the shaper rate as a percentage from the line rate for different average packet sizes and tunnel modes. The larger the packet, the lesser tunnel overhead effect.

Table 12-4 Tunnel Shaper Rates

Packet Size	TunnelAH	Tunnel ESP	TransAH	TransESP
64	0.592593	0.592593	0.727273	0.727273
128	0.744186	0.744186	0.842105	0.842105
380	0.896226	0.896226	0.940594	0.940594
1084	0.958801	0.958801	0.977099	0.977099

QoS Policy Configuration Examples

Simple QoS on Physical Interface Policy

The following QoS example configures Class1 with these characteristics on the Serial 1 /1 interface: a minimum of 200 Kbps of bandwidth are expected to be delivered to this class in the event of congestion, and the queue reserved for this class can enqueue 40 packets before tail drop is employed to handle additional packets.

Class2 is specified with these characteristics: a minimum of 300 Kbps of bandwidth are expected to be delivered to this class in the event of congestion. For congestion avoidance, RED packet drop is used, not tail drop. The default class is configured with a maximum of 20 packets per queue which are enqueued before tail drop is used to handle additional packets.

Begin by creating Class1 and Class2 and matching their respective parameters:

XSR(config)#class-map class1

XSR(config-cmap<class1)#match access-group 136

XSR(config-cmap<class1)#exit

XSR(config)#class-map class2

XSR(config-cmap<class2>)#match ip precedence 2

Create the policy map:

XSR(config)#policy-map policy1

XSR(config-pmap<policy1>)#class class1

XSR(config-pmap-c<class1>)#bandwidth 200

12-24 Configuring Quality of Service