Annotated edit history of
CiscoWiredCountryNotes version 7, including all changes.
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Notes for using a Cisco router to connect to WiredCountry. |
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With connecting up a customer to [WiredCountry], some hosts, irrespective of what Operating System they are running, will not load most web pages, send/recieve email, yet the sites are reachable when pinging them. |
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This is because the [MTU] sizes are reduced and depending on the route path will depend on the [MTU]. For example www.wired.net.nz maximum reachable frame size is 996 bytes. |
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Some network cards will automatically work around the problem, others won't. |
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The workaround solution on a Cisco router is to change the TCP [MSS] option value on SYN packets that traverse through the router (available in IOS 12.2(4)T and higher). This reduces the [MSS] option value in the TCP SYN packet so that it's smaller than the value in the ip tcp adjust-mss value command, in this case 990 ([MTU] minus the size of the IP, TCP, and GRE headers). The end hosts now send TCP/IP packets no larger than this value. |
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<pre> |
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interface Dialer0 |
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ip tcp adjust-mss 990 |
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</pre> |
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Sample Cisco Config to connect a Cisco router to WiredCountry. This only includes to the external interface connection to WiredCountry. |
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<pre> |
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interface Ethernet1 |
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description Wired Country Broadband Network |
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no ip address |
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! Set the load-interval at 30 Secs so that usage graphing is more accurate |
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load-interval 30 |
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pppoe enable |
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pppoe-client dial-pool-number 1 |
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hold-queue 100 out |
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! |
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! |
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interface Dialer0 |
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description Internet Connection to Wired Country |
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ip address negotiated |
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! Entries for the FW/ACLs/IDS/IPS |
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ip access-group Internet in |
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ip inspect Internet in |
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ip ips Internet in |
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! Security Essentials |
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ip verify unicast reverse-path |
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ip virtual-reassembly |
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no ip redirects |
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no ip unreachables |
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no ip proxy-arp |
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no cdp enable |
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! Frame size adjustments |
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ip mtu 1492 |
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ip tcp adjust-mss 996 |
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! Assuming that you're running NAT |
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ip nat outside |
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! Set the load-interval at 30 Secs so that usage graphing is more accurate |
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load-interval 30 |
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! And your PPP encapsualtion/authenication |
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encapsulation ppp |
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dialer pool 1 |
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dialer-group 1 |
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ppp chap hostname <<username>>@wiredcountry.net.nz |
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ppp chap password <<password>> |
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ppp pap sent-username <<username>>@wiredcountry.net.nz password <<password>> |
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! Plus extras |
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hold-queue 100 out |
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! |
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dialer-list 1 protocol ip permit |
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</pre> |
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For routers that use an IOS image older than 12.2(13)T image will also need the following configuration commands added in the configuration. |
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<pre> |
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vpdn enable |
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no vpdn logging |
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! |
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vpdn-group pppoe |
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request-dialin |
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protocol pppoe |
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</pre> |
