http connection failures after installing C2960G switches

[Owen Mould]

I have seen this at two sites now: after migrating the site T1 to 10-Mbps Opt-E-MAN and replacing old 10/100 switches with 10/100/1000 switches, users frequently get http connection errors. The error goes away if the user reloads the page--sometimes they have to reload more than once. They never had this problem before.

I thought it was due to the large number of 5-port desktop switches infesting the networks (I'm getting rid of them as fast as I can) but it happens even on a PC directly connected to one of the new GigE switches. It does not happen when accessing internal web pages.

It looks like a DNS failure -- but nothing has changed in our DNS setup, except that users have a fatter pipe to our DNS servers.

Any ideas? How do I explain to users that giving them a faster network breaks their web browsing?

[Reza Sharifi]

What is the output of "sh ip int gix/x/x"?

gix/x/x is the 10-Mbps interface that connects to the provider

Also, is the connection to the provider fiber or copper?

[Owen Mould]

GigabitEthernet0/0 is up, line protocol is up

  Internet address is 10.100.1.5/24

  Broadcast address is 255.255.255.255

  Address determined by non-volatile memory

  MTU is 1500 bytes

  Helper address is 10.3.0.51

  Directed broadcast forwarding is disabled

  Multicast reserved groups joined: 224.0.0.10

  Outgoing access list is not set

  Inbound  access list is not set

  Proxy ARP is enabled

  Local Proxy ARP is disabled

  Security level is default

  Split horizon is enabled

  ICMP redirects are always sent

  ICMP unreachables are always sent

  ICMP mask replies are never sent

  IP fast switching is enabled

  IP fast switching on the same interface is disabled

  IP Flow switching is disabled

  IP CEF switching is enabled

  IP CEF switching turbo vector

  IP multicast fast switching is enabled

  IP multicast distributed fast switching is disabled

  IP route-cache flags are Fast, CEF

  Router Discovery is disabled

  IP output packet accounting is disabled

  IP access violation accounting is disabled

  TCP/IP header compression is disabled

  RTP/IP header compression is disabled

  Policy routing is disabled

  Network address translation is disabled

  BGP Policy Mapping is disabled

  Input features: Ingress-NetFlow, MCI Check

  Output features: CCE Post NAT Classification, QoS Marking, Post-Ingress-NetFlow, Egress-Netflow

  WCCP Redirect outbound is disabled

  WCCP Redirect inbound is disabled

  WCCP Redirect exclude is disabled

The connection to the provider is copper to a Cisco ME3400; from there on it's fiber.

[Owen Mould]

Found the problem : I'm an idiot. I set the default route as GigE0 -- the int itself. It worked, but the arp table was enormous! I reconfigured it to use EIGRP and all was well. Embarrassing, but I'll leave it up for the edification of others.


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