10-18-2006 03:45 PM - edited 03-03-2019 02:24 PM
I have a T3 connection between two Cisco 3725s. Looking at the PPP longs I see a repetition of this pattern:
*Mar 1 04:23:01.712 pst: Se1/0 LCP: I CONFREQ [ACKsent] id 239 len 14
*Mar 1 04:23:01.712 pst: Se1/0 LCP: MRU 4470 (0x01041176)
*Mar 1 04:23:01.712 pst: Se1/0 LCP: MagicNumber 0x31EA3BB3 (0x050631EA3BB3)
*Mar 1 04:23:01.712 pst: Se1/0 LCP: O CONFACK [ACKsent] id 239 len 14
*Mar 1 04:23:01.712 pst: Se1/0 LCP: MRU 4470 (0x01041176)
*Mar 1 04:23:01.712 pst: Se1/0 LCP: MagicNumber 0x31EA3BB3 (0x050631EA3BB3)
*Mar 1 04:23:02.168 pst: Se1/0 LCP: TIMEout: State ACKsent
*Mar 1 04:23:02.168 pst: Se1/0 LCP: O CONFREQ [ACKsent] id 100 len 14
*Mar 1 04:23:02.168 pst: Se1/0 LCP: MRU 4470 (0x01041176)
*Mar 1 04:23:02.168 pst: Se1/0 LCP: MagicNumber 0x0F2DC891 (0x05060F2DC891)
*Mar 1 04:23:03.728 pst: Se1/0 PPP: I pkt type 0xC021, datagramsize 18 link[ppp
]
It seems that this router can receive packets just fine, but the othe router is not seeing my ACKs. I do not have access to the other router unfortunantly. What would cause one direction of communication to crap out?
Here is the relevant part of my config file:
interface Serial1/0
mtu 4470
bandwidth 40000
ip address 10.1.1.2 255.255.255.252
encapsulation ppp
no ip route-cache
no ip mroute-cache
delay 20
autodetect encapsulation ppp
dsu mode 3
dsu bandwidth 44210
scramble
serial restart_delay 0
10-18-2006 06:55 PM
Shawn
Can you verify that both ends are configured with scramble? In fact can you verify that all the dsu parameters match between the routers? I know that your post says that you do not have access to the other router but can you get someone there to give you their configuration parameters?
From your description that it looks like you receive from the other end but that they do not receive from you it sounds like some kind of mismatch. And I would start with the dsu parameters.
Of course there is also some possibility that yout receive side is good but your transmit side has some physical fault. You might ask the provider to do some testing of the circuit.
HTH
Rick
10-19-2006 06:51 AM
Thanks for the info Rick.
I have some configuration info for the other router and the DSU between the two routers. The DSU is indeed set to scramble on the interface that we use, however the other router uses an HSSI interface that isn't set to scramble.
I'm going to play around with the settings a bit. Do the MTU, bandwidth, etc have to be identical on both sides?
10-19-2006 07:03 AM
Shawn
If one side is set for scramble and the other is not I suspect that this is an issue.
I believe that MTU does not cause a problem if it does not match on both sides. Regular bandwidth does not matter if it does not match on both sides (but if dsu bandwidth is configured you should be careful - in most cases I think it must match).
HTH
Rick
10-19-2006 08:27 AM
I come back this morning and I'm no longer getting incoming packets... what else can go wrong?
10-19-2006 09:17 AM
Even when I'm turning on local loopback, I'm still getting line protocol down.
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