Flapping POS Interface on Frame-relay between a Juniper and Cisco
surfer at mauigateway.com
Tue Dec 6 15:05:39 CST 2011
Did Jeff's suggestion work?
: interface POS0/0/0
: frame-relay intf-type dce
If so, please let the list know, so when someone comes
across this thread while searching for the fix they can
figure it out without having to email the list. If it
didn't help contact me off-line and I will be happy to
troubleshoot it with you.
From: Righa Shake [righa.shake at gmail.com]
Sent: Saturday, November 19, 2011 11:11 AM
To: afnog at afnog.org
Subject: Flapping POS Interface on Frame-relay between a Juniper and Cisco
Am having a problem that is buffling.
I recently changed a POS link encapsulation from PPP to Frame-relay.
Since that time the POS interface keeps resetting from time to time.
On my BGP session am receiving cease notifications from my upstream
The setup is such that we have a cisco on one end and a Juniper on the
no ip address
no ip unreachables
logging event link-status
frame-relay lmi-type ansi
ROUTERshow run int pos0/0/0.101
interface POS0/0/0.101 point-to-point
ip address X.X.X.X 255.255.255.252
frame-relay interface-dlci 101
ROUTER#show int pos0/0/0
POS0/0/0 is up, line protocol is up
Hardware is SPA-2XOC12-POS
MTU 4474 bytes, BW 622000 Kbit/sec, DLY 100 usec,
reliability 255/255, txload 6/255, rxload 38/255
Encapsulation FRAME-RELAY, crc 32, loopback not set
Keepalive set (10 sec)
LMI enq sent 81981, LMI stat recvd 77480, LMI upd recvd 0, DTE LMI up
LMI enq recvd 0, LMI stat sent 0, LMI upd sent 0
LMI DLCI 0 LMI type is ANSI Annex D frame relay DTE segmentation
FR SVC disabled, LAPF state down
Broadcast queue 0/256, broadcasts sent/dropped 26/0, interface broadcasts
Last input 00:00:00, output 00:00:00, output hang never
Last clearing of "show interface" counters 1w2d
Input queue: 0/375/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 94336000 bits/sec, 13151 packets/sec
5 minute output rate 16470000 bits/sec, 7049 packets/sec
12211574207 packets input, 10967607038364 bytes, 0 no buffer
Received 0 broadcasts (0 IP multicasts)
6970870 runts, 2179 giants, 0 throttles
892493293 input errors, 882184781 CRC, 0 frame, 0 overrun, 0 ignored,
6379191154 packets output, 1614018181446 bytes, 0 underruns
0 output errors, 0 applique, 4 interface resets
0 unknown protocol drops
0 output buffer failures, 0 output buffers swapped out
0 carrier transitions
Any assistance on this will be greatly appreciated.
--- jsaxe at briworks.com wrote:
From: Jeff Saxe <jsaxe at briworks.com>
I believe this is the explanation for your flapping: a PPP link is intended to go between two routers over, for instance, a private leased line, so both of the devices are peers, neither one particularly special. Frame-relay, by contrast, was originally designed so that your router was an "end user" device and its directly-connected partner device was not your other router, which you control, but the frame carrier's frame-relay switch. Your router was a DTE device, and their switch, which was in a more "important" position in control of the frame-relay NBMA cloud, was the DCE device. Your router then slaved to the frame switch via LMI signaling, so that the upstream switch instructed you which DLCIs existed and were up at the moment.
So if you connect up two routers with frame-relay encap and each thinks it is the DTE, and neither one is taking the role of the frame switch, then when you bring them up, they will initially optimistically think their DLCIs are up and working, and the routing protocol and traffic will come up... but both of them will be waiting for the frame switch to send them LMI indicating that their idea of the DLCI up/down status is correct. When a couple minutes go by and they don't hear the responses to their LMI enquiries, they will bring all the DLCI's down. I thought they would then stay down forever, i.e., not flap, but maybe you are shutting / no shutting the POS circuit to try again. Anyway, I believe the very simple fix is
frame-relay intf-type dce
So this will turn your Cisco side of the circuit into "DCE" mode, and if the Juniper side stays in "DTE" mode (the default, so probably not listed in the config), then the LMI should start behaving between the two. And yes, as Jay Hennigan suggested, you might need to use "encap frame-relay ietf" to be compatible with non-Cisco gear, or you might need to adjust the frame-relay lmi-type -- one type sends the LMI on DLCI number 0, one of them on DLCI 1023, whatever. I think you'll need to adjust the two ends until you see LMI enquiries both sent and received; right now the "show interface" from the Cisco side shows it has not received any LMI enq yet.
Good luck, and I hope it's that simple. :-)
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