Description

This article describes the issue of the LSQ interface remaining down in a MLFR setup, even though the T1 links are up and work fine, even when moved out of the LSQ bundle.

Symptoms

For example, consider the following common LSQ setup over a Channelized OC48 PIC, which is partitioned into multiple T1 links:

coc48-3/0/0 {
    partition 1 oc-slice 1 interface-type coc1;
    partition 2 oc-slice 2 interface-type coc1;
    partition 3 oc-slice 3 interface-type coc1;
    partition 4 oc-slice 4 interface-type coc1;
    partition 5 oc-slice 5 interface-type coc1;
    partition 6 oc-slice 6 interface-type coc1;
    partition 7 oc-slice 7 interface-type coc1;
    partition 8 oc-slice 8 interface-type coc1;
    partition 9 oc-slice 9 interface-type coc1;
    partition 10 oc-slice 10 interface-type coc1;
    partition 11 oc-slice 11 interface-type coc1;
    partition 12 oc-slice 12 interface-type coc1;

coc1-3/0/0:1 {
    no-partition interface-type ct3;
}
ct3-3/0/0:1 {
     t3-options {
         no-cbit-parity;
     }
partition 1-28 interface-type t1;
}
The LSQ is called under unit 500 :
t1-3/0/0:1:4 {
     encapsulation multilink-frame-relay-uni-nni;
     t1-options {
         timeslots 1-24;
     }
unit 500 {
    family mlfr-uni-nni {
        bundle lsq-9/0/0:1;
    }
}
}
t1-3/0/0:1:8 {
    encapsulation multilink-frame-relay-uni-nni;
    t1-options {
        timeslots 1-24;
    }
unit 500 {
    family mlfr-uni-nni {
        bundle lsq-9/0/0:1;
    }
}
}

lsq-9/0/0:1 {
     dce
     enable;
     encapsulation multilink-frame-relay-uni-nni;
     mlfr-uni-nni-bundle-options {
         lmi-type ansi;
         minimum-links 2;
     }
unit 500 {
    description u284795:dupaco.com:MLFR:2xT1;
    point-to-point;
    dlci 500;
    family inet {
        address 152.179.27.61/30;
    }
}
}
As per the following output, the LSQ interface remains down; also, the T1 links are not attached to the LSQ, even though when they are up/up:
lab@Cobalt-2-RE-0> show interfaces lsq-9/0/0:1 extensive
Physical interface: lsq-9/0/0:1, Enabled, Physical link is Down
Interface index: 336, SNMP ifIndex: 1114, Generation: 377
Link-level type: Multilink-FR-UNI-NNI, MTU: 1508
Device flags : Present Running
Interface flags: Hardware-Down Link-Layer-Down Point-To-Point SNMP-Traps Internal: 0x4000
Last flapped : 2013-03-07 09:39:11 UTC (00:28:30 ago)
Statistics last cleared: Never
Hold-times : Up 0 ms, Down 0 ms
Multilink Frame Relay UNI NNI bundle options:
Device type DCE
MRRU 1508
Bandwidth 0
Fragmentation threshold 0
Red differential delay limit 120
Yellow differential delay limit 72
Red differential delay action Remove link
Reassembly drop timer 65535
Links needed to sustain bundle 2
Link layer overhead 4.0 %
LIP Hello timer 10
Acknowledgement timer 4
Acknowledgement retries 2
Bundle class C
LMI type ANSI
T391 LIV polling timer 10
T392 polling verification timer 15
N391 full status polling count 6
N392 error threshold 3
N393 monitored event count 4
ANSI LMI settings: n392dce 3, n393dce 4, t392dce 15 seconds
LMI statistics:
Input : 0 (last seen: never)
Output: 1 (last sent 00:28:41 ago)
DTE statistics:
Enquiries sent : 0
Full enquiries sent : 0
Enquiry responses received : 0
Full enquiry responses received : 0
DCE statistics:
Enquiries received : 0
Full enquiries received : 0
Enquiry responses sent : 0
Full enquiry responses sent : 0
Common statistics:
Unknown messages received : 0
Asynchronous updates received : 0
Out-of-sequence packets received : 0
Keepalive responses timedout : 1
Interface transmit statistics: Disabled
Traffic statistics:
Input bytes : 0 0 bps
Output bytes : 0 0 bps
Input packets: 0 0 pps
Output packets: 0 0 pps
IPv6 transit statistics:
Input bytes : 0
Output bytes : 0
Input packets: 0
Output packets: 0
Multilink Frame Relay UNI NNI bundle errors:
Packet drops 0 (0 bytes)
Fragment drops 0 (0 bytes)
MRRU exceeded 0
Exception events 0
Multilink Frame Relay UNI NNI bundle statistics:
Frames fps Bytes bps

Multilink:
Input : 0 0 0 0
Output: 0 0 0 0
Network:
Input : 0 0 0 0
Output: 0 0 0 0
Multilink Frame Relay UNI NNI bundle links information:
Active bundle links 0
Removed bundle links 0
Disabled bundle links 0

Logical interface lsq-9/0/0:1.500 (Index 354) (SNMP ifIndex 822)
(Generation 202)
Description: u284795:dupaco.com:MLFR:2xT1
Flags: Hardware-Down Device-Down Point-To-Point SNMP-Traps
Encapsulation: Multilink-FR-UNI-NNI
Last flapped: 2013-03-07 09:39:18 UTC (00:28:23 ago)
Bundle status:
Received sequence number 0x0
Transmit sequence number 0x0
Packet drops 0 (0 bytes)
Fragment drops 0 (0 bytes)
MRRU exceeded 0
Fragment timeout 0
Missing sequence number 0
Out-of-order sequence number 0
Out-of-range sequence number 0
Packet data buffer overflow 0
Fragment data buffer overflow 0
Statistics Frames fps Bytes bps
Bundle:
Multilink:
Input : 0 0 0 0
Output: 0 0 0 0
Network:
Input : 0 0 0 0
Output: 0 0 0 0
Multilink detail statistics:
Bundle:
Fragments:
Input : 0 0 0 0
Output: 0 0 0 0
Non-fragments:
Input : 0 0 0 0
Output: 0 0 0 0
Protocol inet, MTU: 1500, Generation: 250, Route table: 0
Flags: Sendbcast-pkt-to-re
Addresses, Flags: Dest-route-down Is-Preferred Is-Primary
Destination: 152.179.27.60/30, Local: 152.179.27.61,
Broadcast: Unspecified, Generation: 141
DLCI 500
Flags: Down
Total down time: 00:28:23 sec, Last down: 00:28:23 ago
Traffic statistics:
Input bytes : 0
Output bytes : 0
Input packets: 0
Output packets: 0
DLCI statistics:
Active DLCI :0 Inactive DLCI :1

lab@Cobalt-2-RE-0> show interfaces terse | match t1
t1-3/0/0:1:1 up up
t1-3/0/0:1:2 up up
t1-3/0/0:1:3 up up
t1-3/0/0:1:4 up up
t1-3/0/0:1:5 up up
t1-3/0/0:1:6 up up
t1-3/0/0:1:7 up up
t1-3/0/0:1:8 up up

Solution

In a MLFR setup, the following conditions have to be met:

  • Always have one end as DCE and the other end as DTE.

  • On T1 links, always have the bundle configuration at unit 0 .

In the above case, the bundle configuration was under unit 500 , instead of unit 0 :
t1-3/0/0:1:4 {
    encapsulation multilink-frame-relay-uni-nni;
    t1-options {
        timeslots 1-24;
    }
unit 500 {
    family mlfr-uni-nni {
        bundle lsq-9/0/0:1;
    }
}
}
t1-3/0/0:1:8 {
    encapsulation multilink-frame-relay-uni-nni;
    t1-options {
        timeslots 1-24;
    }
unit 500 {
    family mlfr-uni-nni {
        bundle lsq-9/0/0:1;

To resolve this issue, move the T1 bundle configuration to unit 0 :

t1-3/0/0:1:4 {
    encapsulation multilink-frame-relay-uni-nni;
    t1-options {
        timeslots 1-24;
    }
unit 0 {
    family mlfr-uni-nni {
        bundle lsq-9/0/0:1;
    }
}
}
t1-3/0/0:1:8 {
    encapsulation multilink-frame-relay-uni-nni;
    t1-options {
        timeslots 1-24;
}
unit 0 {
    family mlfr-uni-nni {
        bundle lsq-9/0/0:1;

show interfaces terse
t1-3/0/0:1:4.0 up up mfr lsq-9/0/0:1
t1-3/0/0:1:8.0 up up mfr lsq-9/0/0:1
t1-3/1/0:1:4.0 up up mfr lsq-9/1/0:1
t1-3/1/0:1:8.0 up up mfr lsq-9/1/0:1
lsq-9/0/0:1 up up
lsq-9/0/0:1.500 up up inet 152.179.27.61/30