【IT168专稿】CISCO3550交换机作为我们单位的核心网络交换机，已经稳定运行了多年，功能上也能满足我们的需求，但是其端口限速功能却不像其它的一些交换机那样容易实现，好在最近找到了实现的办法，配置完成后，配合iperf这款测速软件进行验证，结果证明这个方法是行之有效的，下面是具体实现步骤。
一、创建ACL
由于这是一台三层交换机，所以虽然是对端口进行限速，但是还要考虑这个端口上通过的网络地址，本例中，我们选择对CISCO3550交换机的第22口进行限速，该端口属于VLAN66，IP地址段为10.66/16，所以首先要创建一个ACL，如下所示：
3550#conf t
Enter configuration commands, one per line. End with CNTL/Z.
3550(config)#access-list 15 permit 10.66.0.0 0.0.255.255
二、创建class-map
3550#conf t
Enter configuration commands, one per line. End with CNTL/Z.
3550(config)#class-map dkxs
3550(config-cmap)#match access-group 15
这一步操作的主要目的就是创建了一个class-map，在这里面引用了我们事先创建好的ACL 15，方便我们以后对22端口进行操作。
三、创建policy-map
出于测试的需要，我们创建了多个policy-map，分别设置不同的限制带宽，如80k，1m，5m，10m，分别如下：
3550#conf t
Enter configuration commands, one per line. End with CNTL/Z.
3550(config)#policy-map 80k
3550(config-pmap)#class dkxs
3550(config-pmap-c)# police 80000 8000 exceed-action drop
3550#conf t
Enter configuration commands, one per line. End with CNTL/Z.
3550(config)#policy-map 1m
3550(config-pmap)#class dkxs
3550(config-pmap-c)# police 1000000 100000 exceed-action drop
3550#conf t
Enter configuration commands, one per line. End with CNTL/Z.
3550(config)#policy-map 5m
3550(config-pmap)#class dkxs
3550(config-pmap-c)# police 5000000 500000 exceed-action drop
3550#conf t
Enter configuration commands, one per line. End with CNTL/Z.
3550(config)#policy-map 10m
3550(config-pmap)#class dkxs
3550(config-pmap-c)# police 10000000 1000000 exceed-action drop
四、查看配置信息
3550#show run
policy-map 5m
class dkxs
police 5000000 500000 exceed-action drop
policy-map 1m
class dkxs
police 1000000 100000 exceed-action drop
policy-map 80k
class dkxs
police 80000 8000 exceed-action drop
policy-map 10m
class dkxs
police 10000000 1000000 exceed-action drop
五、通过iperf软件进行验证
即先在一台服务器上运行iperf的服务器端，命令如下：
F:\tools>iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
然后在交换机的22口上分别应用表示不同速率的policy-map，每应用一次，通过一台连接到22端口的笔记本电脑运行iperf的客户端，进行端口速率测试，结果分别如下：
(交换机设置)
3550(config-if)#service-policy input 80k
(IPERF客户端测试结果)
F:\tools>iperf -c 10.66.66.8
------------------------------------------------------------
Client connecting to 10.66.66.8, TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[1912] local 10.66.123.66 port 1147 connected with 10.66.66.8 port 5001
[ ID] Interval Transfer Bandwidth
[1912] 0.0-12.5 sec 104 KBytes 68.3 Kbits/sec
F:\tools>iperf -c 10.66.66.8
------------------------------------------------------------
Client connecting to 10.66.66.8, TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[1912] local 10.66.123.66 port 1151 connected with 10.66.66.8 port 5001
[ ID] Interval Transfer Bandwidth
[1912] 0.0-12.0 sec 104 KBytes 70.8 Kbits/sec
(交换机设置)
3550(config-if)#service-policy input 1m
(IPERF客户端测试结果)
F:\tools>iperf -c 10.66.66.8
------------------------------------------------------------
Client connecting to 10.66.66.8, TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[1912] local 10.66.123.66 port 1155 connected with 10.66.66.8 port 5001
[ ID] Interval Transfer Bandwidth
[1912] 0.0-10.5 sec 1.08 MBytes 860 Kbits/sec
F:\tools>iperf -c 10.66.66.8
------------------------------------------------------------
Client connecting to 10.66.66.8, TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[1912] local 10.66.123.66 port 1159 connected with 10.66.66.8 port 5001
[ ID] Interval Transfer Bandwidth
[1912] 0.0-10.0 sec 1.09 MBytes 910 Kbits/sec
(交换机设置)
3550(config-if)#service-policy input 5m
(IPERF客户端测试结果)
F:\tools>iperf -c 10.66.66.8
------------------------------------------------------------
Client connecting to 10.66.66.8, TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[1912] local 10.66.123.66 port 1163 connected with 10.66.66.8 port 5001
[ ID] Interval Transfer Bandwidth
[1912] 0.0-10.5 sec 5.84 MBytes 4.67 Mbits/sec
F:\tools>iperf -c 10.66.66.8
------------------------------------------------------------
Client connecting to 10.66.66.8, TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[1912] local 10.66.123.66 port 1167 connected with 10.66.66.8 port 5001
[ ID] Interval Transfer Bandwidth
[1912] 0.0-10.7 sec 5.98 MBytes 4.68 Mbits/sec
(交换机设置)
3550(config-if)#service-policy input 10m
(IPERF客户端测试结果)
F:\tools>iperf -c 10.66.66.8
------------------------------------------------------------
Client connecting to 10.66.66.8, TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[1912] local 10.66.123.66 port 1171 connected with 10.66.66.8 port 5001
[ ID] Interval Transfer Bandwidth
[1912] 0.0-10.1 sec 11.8 MBytes 9.83 Mbits/sec
F:\tools>iperf -c 10.66.66.8
------------------------------------------------------------
Client connecting to 10.66.66.8, TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[1912] local 10.66.123.66 port 1175 connected with 10.66.66.8 port 5001
[ ID] Interval Transfer Bandwidth
[1912] 0.0-10.2 sec 12.0 MBytes 9.87 Mbits/sec
为了使测试的结果更准确，每种速率下都进行了两次测试，从测试的结果看，端口限速确实生效了。
