经过几年的使用。我们已经看到 Cisco 871 和 851 路由器如果您的单次下载超过 100M 就会挂起。它是间歇性的。有时问题会消失，有时它会发生在非常小的下载（只有 10KB 的网页）上。似乎几乎所有的下载最终都会完成，但下载量越大，挂起的时间就越长。
有没有办法解决这个问题？（缺少路由器更换，这是我们一直在做的）
我们正在使用一年零两个月的Cisco 851重新审视这一点。在这一点上，类似的挂起似乎正在发生，但规模要小得多。在这种情况下，客户购买了30Mbps上行/下行互联网连接，他们只能获得5Mbps/20Mbps上行/下行。有时，下载速度会降低到 5Mbps。
下次我在那里时（希望下周），我将尝试下面已经提出的建议，并在我的发现中进行编辑。
我在 Vlan1 和 Fa4 上有一个 ACL。我还有一些 ACL 已被替换且未使用。ACL 大约有 45 行，其中大约一半是备注。我已经在下面发布了配置。个人信息被诸如WAN IP或hostname HIDDEN
如果您有诸如配置代码的性能改进之类的建议，或诸如我是否可以在 851 上预期 30Mbps 之类的信息，我们将不胜感激。
Current configuration : 18157 bytes
!
version 12.4
no service pad
service tcp-keepalives-in
service tcp-keepalives-out
service timestamps debug datetime msec localtime show-timezone
service timestamps log datetime msec localtime show-timezone
service password-encryption
service sequence-numbers
!
hostname HIDDEN
!
boot-start-marker
boot-end-marker
!
logging buffered 51200
logging console critical
enable secret 5 --GIBBERISH---
!
aaa new-model
!
!
aaa authentication login local_authen local
aaa authorization exec local_author local
!
!
aaa session-id common
clock timezone EST -5
!
crypto pki trustpoint TP-self-signed-4140887523
enrollment selfsigned
subject-name cn=IOS-Self-Signed-Certificate-4140887523
revocation-check none
rsakeypair TP-self-signed-4140887523
!
!
dot11 syslog
no ip source-route
no ip dhcp use vrf connected
ip dhcp binding cleanup interval 60
ip dhcp excluded-address 10.10.10.1
ip dhcp excluded-address 192.168.1.1
!
ip dhcp pool ccp-pool
import all
network 10.10.10.0 255.255.255.248
default-router 10.10.10.1
lease 0 2
!
ip dhcp pool sdm-pool1
import all
network 192.168.1.0 255.255.255.0
dns-server --DNS Server 1-- --DNS Server 2--
default-router 192.168.1.1
!
!
ip cef
ip inspect name DEFAULT100 appfw DEFAULT100
ip inspect name DEFAULT100 cuseeme
ip inspect name DEFAULT100 ftp
ip inspect name DEFAULT100 h323
ip inspect name DEFAULT100 icmp
ip inspect name DEFAULT100 rcmd
ip inspect name DEFAULT100 realaudio
ip inspect name DEFAULT100 rtsp
ip inspect name DEFAULT100 esmtp
ip inspect name DEFAULT100 sqlnet
ip inspect name DEFAULT100 streamworks
ip inspect name DEFAULT100 tftp
ip inspect name DEFAULT100 tcp
ip inspect name DEFAULT100 udp
ip inspect name DEFAULT100 vdolive
ip inspect name DEFAULT100 https
ip inspect name DEFAULT100 dns
no ip bootp server
no ip domain lookup
ip domain name noexist.example.com
ip name-server --DNS Server 2--
ip name-server --DNS Server 1--
!
appfw policy-name DEFAULT100
application im aol
service default action reset
service text-chat action reset
server deny name login.oscar.aol.com
server deny name toc.oscar.aol.com
server deny name oam-d09a.blue.aol.com
application im msn
service default action reset
service text-chat action reset
server deny name messenger.hotmail.com
server deny name gateway.messenger.hotmail.com
server deny name webmessenger.msn.com
application http
port-misuse im action reset alarm
application im yahoo
service default action reset
service text-chat action reset
server deny name scs.msg.yahoo.com
server deny name scsa.msg.yahoo.com
server deny name scsb.msg.yahoo.com
server deny name scsc.msg.yahoo.com
server deny name scsd.msg.yahoo.com
server deny name messenger.yahoo.com
server deny name cs16.msg.dcn.yahoo.com
server deny name cs19.msg.dcn.yahoo.com
server deny name cs42.msg.dcn.yahoo.com
server deny name cs53.msg.dcn.yahoo.com
server deny name cs54.msg.dcn.yahoo.com
server deny name ads1.vip.scd.yahoo.com
server deny name radio1.launch.vip.dal.yahoo.com
server deny name in1.msg.vip.re2.yahoo.com
server deny name data1.my.vip.sc5.yahoo.com
server deny name address1.pim.vip.mud.yahoo.com
server deny name edit.messenger.yahoo.com
server deny name http.pager.yahoo.com
server deny name privacy.yahoo.com
server deny name csa.yahoo.com
server deny name csb.yahoo.com
server deny name csc.yahoo.com
!
!
!
username surfn privilege 15 secret 5 $1$1hrm$0yfIN0jK56rOm9cXfm2a21
!
!
archive
log config
hidekeys
!
!
ip tcp synwait-time 10
ip ssh time-out 60
ip ssh authentication-retries 2
!
!
!
interface Null0
no ip unreachables
!
interface FastEthernet0
!
interface FastEthernet1
!
interface FastEthernet2
!
interface FastEthernet3
!
interface FastEthernet4
description $ES_WAN$$FW_OUTSIDE$
ip address --WAN IP-- 255.255.255.0
ip access-group 123 in
ip verify unicast reverse-path
no ip redirects
no ip unreachables
no ip proxy-arp
ip inspect DEFAULT100 out
ip nat outside
ip virtual-reassembly
ip route-cache flow
duplex auto
speed auto
!
interface Vlan1
description $ETH-SW-LAUNCH$$INTF-INFO-HWIC 4ESW$$ES_LAN$$FW_INSIDE$
ip address 192.168.1.1 255.255.255.0
ip access-group 102 in
no ip redirects
no ip unreachables
no ip proxy-arp
ip nat inside
ip virtual-reassembly
ip route-cache flow
ip tcp adjust-mss 1452
!
ip forward-protocol nd
ip route 0.0.0.0 0.0.0.0 --ISP Gateway--
!
ip http server
ip http access-class 2
ip http authentication local
ip http secure-server
ip http timeout-policy idle 60 life 86400 requests 10000
ip nat inside source list 1 interface FastEthernet4 overload
!
logging trap debugging
access-list 1 remark Telnet, SSH access
access-list 1 permit 192.168.1.0 0.0.0.255
access-list 1 deny any
access-list 2 remark HTTP, HTTPS access
access-list 2 permit 192.168.1.0 0.0.0.255
access-list 2 deny any
access-list 101 HIDDEN
access-list 102 HIDDEN
access-list 121 HIDDEN
access-list 122 HIDDEN
access-list 123 HIDDEN
no cdp run
!
control-plane
!
banner exec ^C
% Password expiration warning.
-----------------------------------------------------------------------
Cisco Configuration Professional (Cisco CP) is installed on this device
and it provides the default username "cisco" for one-time use. If you have
already used the username "cisco" to login to the router and your IOS image
supports the "one-time" user option, then this username has already expired.
You will not be able to login to the router with this username after you exit
this session.
It is strongly suggested that you create a new username with a privilege level
of 15 using the following command.
username <myuser> privilege 15 secret 0 <mypassword>
Replace <myuser> and <mypassword> with the username and password you
want to use.
-----------------------------------------------------------------------
^C
banner login ^CCAuthorized access only!
Disconnect IMMEDIATELY if you are not an authorized user!^C
!
line con 0
login authentication local_authen
no modem enable
transport output telnet
line aux 0
login authentication local_authen
transport output telnet
line vty 0 4
access-class 100 in
privilege level 15
authorization exec local_author
login authentication local_authen
transport input telnet ssh
!
scheduler max-task-time 5000
scheduler allocate 4000 1000
scheduler interval 500
end
这些路由器背后有多少用户？据推测，您正在单个外部地址上执行 NAT。现代软件，尤其是像 facebook 聊天之类的网络服务，打开了很多并发 TCP 连接。我相信 Cisco 有一个静态大小的 NAT 转换表。它可能会溢出并驱逐最旧的连接？恐怕我无法提供任何关于检查 NAT 表是否溢出的建议。
我不会怀疑固件，特别是如果它在几年前一直正常工作的话。但是，我建议快速检查一下接口统计信息。如果您在接口上看到丢弃、无效、badrx 校验和等错误，那么这很可能是您的问题的根源。硬件故障、电气隔离不足或其他原因。我已经停止计算有多少“便宜”的 5 端口 10/100 或千兆交换机在过去的 3-4 年里由于内部膨胀/爆炸电容器而出现半故障并变得不一致和不稳定。一种
show interfaces counters errors
语句应该非常快速地识别任何有问题的接口。
祝你好运。