Private Line T1 and Two 1841s

I feel like an idiot I have looked at this for so long.  I have two 1841s with a T1 CSU/DSU and a T1 crossover cable between the serial ports.  I have each serial setup with 'framing esf' and 'timeslot all speed 24' and 'linecode b8zs' and "fair-que' and encapsulation ppp and ip addresses and internal timesource.  From either router I can ping the other routers fa and serial interfaces.  On one of the routers I can ping things hanging off the fa interface of the other router, but I can not from the other router.  I believe that they are configured the same and can not determine why I can not ping something off the other routers FA port.  Specifically, Router 3 can ping a switch off Router4's FA port, but Router4 can not ping a switch off Router3's FA port.  A traceroute from Router4 to the switch hanging on Router3 FA interface starts looping once it hits router3's serial interface and times out.  Can anyone see an obvious reason I am missing?  I have included 'sho ver', 'sho run', 'sho ip route', and 'sho ip int brief'. Router3-1841.log Router4-1841.log
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Lee_YCPAsked:
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Ernie BeekExpertCommented:
Default route on router 3 perhaps?
ip route 0.0.0.0 0.0.0.0 FastEthernet0/0
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John MeggersNetwork ArchitectCommented:
One side points the default route to the other router, the other side points its default route to the local LAN.  My guess is you probably want both defaults pointing to the other router.  Am I wrong about that?
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Ernie BeekExpertCommented:
Damn I'm fast!

;)
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John MeggersNetwork ArchitectCommented:
Clearly faster than me..... ;-)
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Lee_YCPAuthor Commented:
The default route for router 4 should be its own serial interface, which is connected to router 3 serial int.  In other words, the out to the internet is an ASA hanging off the 10.0/24 subnet of the Router 3 FA interface.
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Lee_YCPAuthor Commented:
I think my last post may have been confusing.  The default route for Router 3 should be out its fa int. The default for Router 4 should be out is own Serial int to Router 3.   I used the local int vs the remote ip when I set the default routes for no particular reasons.  
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John MeggersNetwork ArchitectCommented:
Are you sure you're advertising all relevant routes into RIP?  Typically if you have a route to something and can't ping it, the problem is the other end doesn't know how to get back to the source of the ping.  Hence the question about the default routes.  Check the default gateway on the host trying to respond to the ping, make sure that default gateway knows where to find the source of the ping.
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Lee_YCPAuthor Commented:
Additionally, a traceroute from Router 4 to the 3750 hangin off the Router 3 FA int stops at the Router 3 Serial int.

From Router3:
a ping to either int on Router 4 is successful.
a ping to a switch on the router3 int is unsuccessful.
a traceroute to that switch, x.x.10.3, (that is connected to Router 3 FA int) shows that it hits the Router 3 int, then all other hops are "*" until it times out.
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Lee_YCPAuthor Commented:
scratch the last post, it is wrong and will confuse
"Additionally, a traceroute from Router 4 to the 3750 hangin off the Router 3 FA int stops at the Router 3 Serial int.

From Router3:
a ping to either int on Router 4 is successful.
a ping to a switch on the router3 int is unsuccessful.
a traceroute to that switch, x.x.10.3, (that is connected to Router 3 FA int) shows that it hits the Router 3 int, then all other hops are "*" until it times out."

It should read:
Additionally, a traceroute from Router 4 to a 3750 hangin off the Router 3 FA int stops at the Router 3 Serial int.

From Router4:
a ping to either int on Router 3 is successful.
a ping to a switch on the router3 int is unsuccessful.
a traceroute to that switch, x.x.10.3, (that is connected to Router 3 FA int) shows that it hits the Router 3 int, then all other hops are "*" until it times out.
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Lee_YCPAuthor Commented:
Jmeggars:
The item trying to be pinged is a switch, 192.168.10.3.  Its a 3750 switch and the IP is vlan1 of the switch.  RIP is not enabled on that switch.  Are you saying it should be?
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Lee_YCPAuthor Commented:
Jmeggars:
The 10.0/24 network gateway is 10.1.  It has 'network' entries for 20.0/30 and 11.0/24.  I can ping from router3 to the switch on the 11.0/24 network.  This is the config on the switch if that helps to determine issue: Switch01-3750.log
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John MeggersNetwork ArchitectCommented:
It shouldn't need to be as long as the switch has a default gateway pointing to a device that has route a route back to the source.
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Lee_YCPAuthor Commented:
The routes on the gateway, i.e. 10.1, are:
xFIRE01# sho route

Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
       i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
       * - candidate default, U - per-user static route, o - ODR
       P - periodic downloaded static route

Gateway of last resort is x.x.x.49 to network 0.0.0.0

C    192.168.9.0 255.255.255.0 is directly connected, DMZ
C    192.168.10.0 255.255.255.0 is directly connected, inside
R    192.168.11.0 255.255.255.0 [120/2] via 192.168.10.62, 0:00:19, inside
R    192.168.20.0 255.255.255.252 [120/1] via 192.168.10.62, 0:00:19, inside
C    x.x.x.48 255.255.255.248 is directly connected, Outside
S*   0.0.0.0 0.0.0.0 [1/0] via x.x.x.49, Outside
xFIRE01#
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John MeggersNetwork ArchitectCommented:
First, let me make sure I understand the topology.  R3 has the 3750 switch hanging off its FE interface on the 10.0/24 subnet.  There's a serial connection over to R4 on the 20.0/30.  R4's LAN is 11.0/24 and I can see in R4's routing table that he has a route to the 10.0/24 subnet.   I can see in R3's routing table a route back to the 11.0/24 subnet.

What you're seeing is if you ping from R3 to the 3750 switch, it succeeds, but if you ping from R4, the ICMP traffic appears to die at R3.  Are you specifying a source interface for the pings?  It should default to the serial interface as the source.

I just did a quick test on some gear and it worked for me.  Remote router with a loopback of 192.168.11.1, serial link in the 192.168.20.0/30 subnet, and the LAN link on the other router in 192.168.10.0 subnet, with the switch 192.168.10.3, default-gateway pointing to 192.168.10.1.  I pinged from the remote router sourcing off Lo0 (192.168.11.1) going to 192.168.10.3 and the ping succeeded.

Can you ping from the switch to the serial interface of R4?  What about pinging to the LAN interface of R4?
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Lee_YCPAuthor Commented:
Anyone have a command they want run for clarification?  I will also perform some type of ridiculous task if it will help (as long as it does not include me sleeping with someone).
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Lee_YCPAuthor Commented:
First, let me make sure I understand the topology.  R3 has the 3750 switch hanging off its FE interface on the 10.0/24 subnet.  There's a serial connection over to R4 on the 20.0/30.  R4's LAN is 11.0/24 and I can see in R4's routing table that he has a route to the 10.0/24 subnet.   I can see in R3's routing table a route back to the 11.0/24 subnet.
All correct.

What you're seeing is if you ping from R3 to the 3750 switch, it succeeds, but if you ping from R4, the ICMP traffic appears to die at R3.  Are you specifying a source interface for the pings?  It should default to the serial interface as the source.
The ICMP traffic appears to die at the R3 serial int.  There is a 3750 hanging off the R4 fa int as well, that is 11.3.  I did not include any extra information on it for fear of confusing the issue.  No, I am not specifying a source int from R4 when I do the ping.  You want me to run an extended ping and specify a particular R4 int?

I just did a quick test on some gear and it worked for me.  Remote router with a loopback of 192.168.11.1, serial link in the 192.168.20.0/30 subnet, and the LAN link on the other router in 192.168.10.0 subnet, with the switch 192.168.10.3, default-gateway pointing to 192.168.10.1.  I pinged from the remote router sourcing off Lo0 (192.168.11.1) going to 192.168.10.3 and the ping succeeded.
"The R4 router with a loopback of 11.1", not sure what you mean here.  R4 has a default route of Serial0/0/0 which should get it back to R3 and the 10.0/24 subnet.  It gets it to the serial0/0/0 on the R3 router, but the traceroute stops there.  The R4 FA int is 11.62.  The intended 11.1 device that you mention is not currently connected on the 11.0/24 subnet in my network.
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Lee_YCPAuthor Commented:
Simplified net diagram Drawing11111.pdf
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Lee_YCPAuthor Commented:
Looking at the "sho ip route" on each router.  Is there any significance to R3 having 3 entries for the variably subnetted 20.0/24 and R4 only having two variably subnetted entries?
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Lee_YCPAuthor Commented:
jmeggars, was your test done with autosummary on or off?
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John MeggersNetwork ArchitectCommented:
The loopback interface is just a virtual interface, I did that since I had no device to connect to the Ethernet side of the router that would activate the interface.  So the loopback interface just simulates an active LAN interface on the router.  The fact that I used 11.1 instead of 11.62 doesn't matter.

I did not turn off auto-summary.  I also did not configure any default routes, but as long as the specifics are advertised, the defaults don't mean anything.

I now understand why it's not working.  When you said the default gateway of the switch was pointing to 10.1, I didn't realize that was on an ASA, not on R3.  The switch thinks its default gateway is the ASA firewall and the ASA will not do a redirect.  Given the topology you show, I would enable routing on the 3750 and have it participate in RIP.  That way it will know exactly where the 11.0/24 subnet is located.

Incidentally, you're advertising routes on routers that don't have those subnets, which is not horrible, but it's not what I would call good form.  For example, on R4 you're advertising the 10.0 subnet into RIP, which doesn't exist on that side of the network.  You should only list in the RIP config the networks you have on that router.  So R4 only needs network statements for 11.0/24 and 20.0/30.  The other network statements just complicate the configuration unnecessarily.  
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Lee_YCPAuthor Commented:
Ok, I'll give it a go and check back soon.
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