Re: Some theoretical issue

toruzzz · ‎07-05-2005

Hi TAC!

I have a little theoretical issue!

I already solved my problem, but I want to understand reason of this problem!

I have 2 router connected together through frame-relay link:

router A:

interface Serial0

ip address 10.20.30.1 255.255.255.0

encapsulation frame-relay

frame-relay interface-dlci 16

interface Ethernet0

ip address 172.16.34.66 255.255.255.0

router B:

interface serial0

ip address 10.20.30.2 255.255.255.252

encapsulation frame-relay

frame-relay interface-dlci 16

frame-relay intf-type dce

But then I ping from B(10.20.30.2) to A(10.20.30.1) I see that some ICMP packets not returned - it's look like:

Sending 5000, 100-byte ICMP Echos to 10.20.30.1, timeout is 2 seconds:

.......................!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!!!!!..............................!!!!!!!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!!!!!!!..............................

Success rate is 98 percent (4910/5000), round-trip min/avg/max = 44/46/272 ms

As You can see - I have some appropriateness!

There are some sets of dots(".") - 30 pieces => 30 * 2 sec(timeout) = 60 sec

60 seconds I don't have ICMP pacets back, but after this 60 second time out I have again.

The problem was in the irregular netmask on Serial0 router A, after my changing from /24 to /30

I don't have any problems!

The question is - what kind of timers can do it(may be some frame-relay keepalive)?

TIA

---

Yev.

Georg Pauwen · ‎07-05-2005

Hello Yev,

I have tried to reproduce your problem in a lab environment, but all my pings go through...

I am thinking that your provider is using a routing protocol that might get confused with your different networks. You could use a utility such as PINg Plotter (www.pingplotter.com) and check at which hop the packet loss occurs. The utility also shows you changes in the routing path between two hosts.

HTH,

GP