Couldn't access to some WebSites with cisco 831

Hello,

I've got today my new cisco router type series 831. There was no problem to
install and configure them with the connection-strings. But something is
wrong: On some websites, I've absolutly no problem to access, other websites
are not able to access.

To some websites, I couldn't access, it's possible to send a ping and get
answer, other (existing) sites not.

But there is no problem to acess to all working websites, without the
router. The problems are with firewall and without.

Any Idea, how to selv the problem?????

Thanks and best regards ....

 

Allow ICMP through. Or at the very least ICMP type 3 code 4.

--

hsb

"Somehow I imagined this experience would be more rewarding" Calvin
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If using pppoe, a lot of ISP's block the packets necessary for ip mtu
discovery to work properly. PPPOE is troublesome because of the additional
header information it packs. In most cases, this can be resolved for by
adjusting the tcp mss. To do so try the command "ip tcp adjust-mss 1452" on
your internet facing interface.

 

I had to troubleshoot a similar problem once. The problem was the IP
MTU was adjusted but the TCP MSS (Max Segment Size) was not.

Connections to those sites (that did not work) had the 'do not
fragment' bit set during the initial TCP/IP negotiations between the 2
host (LAN PC and external Web Server). Users needed to recieve larger
packets through than allowed by the clients router and the router
tried to fragment (responce data - on the way back in). Since the
Don't Fragment bit was set between the 2 host (LAN PC and external Web
Server) the connection hung up since the data offset was not 0 in the
packets (fragmented).

*** a tell tell sign (besides using a sniffer of course), was whenever
I tried to browse to linux.org the screen would turn yellow
(background) but none of the graphics would display.***

Play around with the MTU and TCP MSS settings, if possible.
the 831's have 2 ethernet interfaces right? if you can post the
config, but take all your sensitive settings out (IP, passwds, etc)

either that or the isp's dns server that you are using is
broke.........


Don Mega