Solved: Re: Addressing issue with 4506 and 2960 switches

rlopez · ‎11-16-2010

hi,

I have a comminucation problem with some users, the configuration ports on 4506 and 2960 switches is really simple

interface GigabitEthernet2/3
switchport mode access
switchport voice vlan 2
auto qos voip cisco-phone
qos trust device cisco-phone
service-policy input AutoQos-VoIP-Input-Cos-Policy
service-policy output AutoQos-VoIP-Output-Policy

4506 has in its interface vlan 1 the IP address 192.168.10.1/16 this is the default gateway of the network. I'm usin vlan 3 as the administrative vlan for the other switches, the addressing for that vlan is 10.X.X.X/24, I have a DHCP server with IP address 192.168.10.12 which is the FW of the network for internet. the problem is, when a pc sends an IP address request it gets an IP address 192.168.1.221/16 but this pc can't ping 192.168.10.1 nor 192.168.10.12 nor 192.168.10.5 (dns) the computer has no access to internet, it can ping a public dns though. The PC can telnet 4506 switch through the 10.X.X.X interface and also can ping the 4506 in the other interfaces (voice vlan for example). When I set the network mask to 24 bits instead of 16 everything work just fine. I tried to connect the pc in other switch (2960) and the behavior was the same. The other PCs have no problem with a 16 bits networmask.

Why this is happenning and how can I fix it?

Thank you in advance for your help.

kyukim · ‎11-16-2010

Hi.

I would check

1. make sure PC has correct def gw by "ipconfig/all" from CMD --> make sure it points to 4500 vlan1

2. check PC arp table by "arp -a" from CMD --> check if it has correct arp for def gw and dns and fw

3. check PC routing table by "route print" --> check route points to correct GW and interface

4. Trace route to public DNS and check if it goes through correct def GW. --> probably, it is not going through correct GW(4500 vlan1)

KK

View solution in original post

kyukim · ‎11-16-2010

Hi.

I would check

1. make sure PC has correct def gw by "ipconfig/all" from CMD --> make sure it points to 4500 vlan1

2. check PC arp table by "arp -a" from CMD --> check if it has correct arp for def gw and dns and fw

3. check PC routing table by "route print" --> check route points to correct GW and interface

4. Trace route to public DNS and check if it goes through correct def GW. --> probably, it is not going through correct GW(4500 vlan1)

KK

rlopez · ‎11-17-2010

hi Kyuhwan,

thank you very much for your help, it was due a persistent route on the pc, i just deleted it and everything is working perfectly.

regards,

Alex