No routing between physically connected subnets

[skk391]

Hi all,

I have the following issues.... can someone please help....?



Subnet 1 10.1.1.x -----> Router <----- Subnet 2 172.16.0.x
int fa 0/1 int fa 0/0
10.1.1.28 172.16.0.1




The router can ping host on all subnets i.e 10.1.1.12 10.1.1.2 172.16.0.6

but host connected to the 172.16.0.x subnet cannot ping 10.1.1.2 10.1.1.12 the domain controller is on the 10.1.1.x subnet.

the two subnets are physically connected to the router. I have tried to add a gateway of last resort just in case but will no luck.


--------------------------------------------------------------
Gateway of last resort is 0.0.0.0 to network 0.0.0.0

172.16.0.0/24 is subnetted, 1 subnets
C 172.16.0.0 is directly connected, FastEthernet0/0
10.0.0.0/24 is subnetted, 2 subnets
C 10.1.1.0 is directly connected, FastEthernet0/1
S 10.0.0.0 is directly connected, FastEthernet0/1
S* 0.0.0.0/0 is directly connected, FastEthernet0/1
Router#
----------------------------------------------------------------
There are no access-lists configured on the router. No windows firewalls etc.


Any idea's anyone?

 

[dgrizzard]

What did you set the gateway address as for the client PCs?

 

[skk391]

I have tried both 10.1.1.28 & 172.16.0.1

 

[unclerico]

this is going to sound like a stupid question, but is IP Routing enabled on the router??

I hate all Uppercase... I don't want my groups to seem angry at me all the time! =)
- ColdFlame (vbscript forum)

 

[imbadatthis]

also have you tried pinging using the extended ping command ?
ie can you ping from the 10.0 interface to the 172.16 interface ?


We must go always forward, not backward
always up, not down and always twirling twirling towards infinity.

 

[skk391]

update on troubleshooting with this issue. Thanks for everyones input. I can ping from the 10.1.1.x subnet to anything on the 172.16.0.x without
any issues. The problem is the other way round I cannot ping from 17.16.0.x to 10.1.1.x. Running tracert on one of the 172.16.0.x host to 10.1.1.x the ping can
get to the 172.16.0.1 interface of the router but nothing after that.

Any other troubleshooting idea's from anyone?

 

[leedsit]

Hi,

are you 100% sure your subnet masks on the servers, routers etc are correct and the same(relative to the subnet)? and your default gateways are correctly the cisco local interface?

Lee.

LEEroy
CCNP,CCIP

 

[skk391]

Hi,

Thanks for the input. Yes the I have configured the router as a DHCP server for the 172.16.0.x range. Its giving out the correct ip address & gateway to the host requesting DHCP. ie. 172.16.0.x and 172.16.0.1 as the gateway. From one the hosts on the 172.16.0.x I can ping the 172.16.0.1 & 10.1.1.28 interfaces of the router. But not anything else on the 10.1.1.x range. I do not have any ACL's configured.

 

[iolair]

Not to sound condesending, but do you have either a static route(s) configured or a routing protocol configured?

Iolair MacWalter
Network Engineer

 

[unclerico]

first thing you need to do is run Wireshark on a host in the 10.1.1.x range to see if the traffic is getting there.

at firt glance it seems like there is a SNM or gateway issue on the 10.1.1.x network, but you say that you can ping from 10 to 172 so that shouldn't be an issue.

post your scrubbed config.

I hate all Uppercase... I don't want my groups to seem angry at me all the time! =)
- ColdFlame (vbscript forum)

 

[skk391]

Update and result!

leedsit was on the right line. The hosts had the correct gateway's etc but the servers which I needed to ping had a different gateway. The gateway address was still on the same subnet i.e 10.1.1.1 but I couldnt ping from my hosts until I changed the gateway on the server to the router's 10.1.1.28 interface. We do have another gateway on the network. I a little unsure why it will only ping once the default gateway had been changed, but thats how I got it to work.....

 

[leedsit]

Good result! Guess the other gateway doesnt have a route to 172.16.0.0/24 via 10.1.1.28.

lee

LEEroy
CCNP,CCIP