Thursday, February 24, 2011

adding static DNS entry to Window XP or changing the DNS server

Today I find I cannot access some sites.
By checking with the nslookup, found it is blocked by my DNS provider.
There are two ways to work around:
1) change the primary DNS server to the one not blocked or still working under Local Area Connection.
2) change the hosts file under C:\WINDOWS\system32\drivers\etc
add the ip address you find with your site name
xxx.xxx.xxx.xxx    site_name

Wednesday, February 16, 2011

route-map case

There is a someone wants to configure such scenario.
if the router see some port then use a gateway, the solution is using route-map and apply it to the interface.

conf t
route-map port80
match ip address matchport80
set ip next-hop xxx.xxx.xxx.xxx <----------- the gateway ip you set for next-hop for the http traffic


ip access-list extended matchport80
 permit tcp any any eq www

interface FastEthernet0/0
 ip policy route-map port80

Tuesday, February 1, 2011

Cisco IP advance feature - sweep range of sizes

To check the destination ip mtu, please use the following method.
router#ping
Protocol [ip]:
Target IP address: 10.30.30.1
Repeat count [5]: 1
Datagram size [100]: 1
% A decimal number between 36 and 18024.
Datagram size [100]: 100
Timeout in seconds [2]:
Extended commands [n]: y
Source address or interface:
Type of service [0]:
Set DF bit in IP header? [no]: y
Validate reply data? [no]:
Data pattern [0xABCD]:
Loose, Strict, Record, Timestamp, Verbose[none]:
Sweep range of sizes [n]: y
Sweep min size [36]: 1470
Sweep max size [18024]: 1500
Sweep interval [1]:
Type escape sequence to abort.
Sending 31, [1470..1500]-byte ICMP Echos to 10.30.30.1, timeout is 2 seconds:
!!!!!..........................
Success rate is 16 percent (5/31), round-trip min/avg/max = 52/67/88 ms