Dear all, thank you very much for your replies.
I add some more details about topology, i attach an image.
As you can see, on the side of MX there is an ae because is connected with a stack of EX3300, so the connection between MX and SRX is not direct, in the middle there are two devices under our administratión (an stack and standalone EX3300), and two QinQ links contracted from two providers. The ports of my EX3300 conected to each provider are simply dot1q trunks, the qinq encapsulation is transparent for me. This ports on EX3300, doesnt admit the same vlans, so i dont see problems related with STP or L2 loops.
The case that I commented before, is related with VLAN 551, but on VLAN 553 that i put in the attached image, i have a similar configuration between the sames devices (another peer bgp, same configuratión over other subnet), and works fine, the session is up since 4 weeks ago. So, there may be a problem related to "provder 1".
In respect of MTU, are you refering to media MTU or protocol MTU? It could be convenient increase the media MTU in all interfaces involved in this path? I know that both providers admit jumbo frames. However, i don't see errors in the interfaces of SRX, how can i troubleshoot MTU issues more accurately?
SRX - interface ge-0/0/0:
admin@"SRX"# run show interfaces ge-0/0/0 extensive
Physical interface: ge-0/0/0, Enabled, Physical link is Up
Interface index: 134, SNMP ifIndex: 508, Generation: 137
Description: TRUNK-"PROVIDER1"
Link-level type: Ethernet, MTU: 1514, Link-mode: Full-duplex, Speed: 1000mbps, BPDU Error: None, MAC-REWRITE Error: None, Loopback: Disabled, Source filtering: Disabled, Flow control: Disabled,
Auto-negotiation: Enabled, Remote fault: Online
Device flags : Present Running
Interface flags: SNMP-Traps Internal: 0x0
Link flags : None
CoS queues : 8 supported, 8 maximum usable queues
Hold-times : Up 0 ms, Down 0 ms
Current address: f4:b5:2f:89:3b:bb, Hardware address: f4:b5:2f:89:3b:bb
Last flapped : 2017-11-15 23:57:51 ART (7w1d 17:20 ago)
Statistics last cleared: 2017-11-28 01:46:09 ART (5w3d 15:32 ago)
Traffic statistics:
Input bytes : 8511109371495 5197400 bps
Output bytes : 5757191123681 10281808 bps
Input packets: 1645955461 1423 pps
Output packets: 54680961 902 pps
Input errors:
Errors: 0, Drops: 0, Framing errors: 0, Runts: 0, Policed discards: 0, L3 incompletes: 0, L2 channel errors: 0, L2 mismatch timeouts: 0, FIFO errors: 0, Resource errors: 0
Output errors:
Carrier transitions: 0, Errors: 0, Drops: 0, Collisions: 0, Aged packets: 0, FIFO errors: 0, HS link CRC errors: 0, MTU errors: 0, Resource errors: 0
Egress queues: 8 supported, 4 in use
Queue counters: Queued packets Transmitted packets Dropped packets
0 best-effort 0 0 0
1 expedited-fo 0 0 0
2 assured-forw 0 0 0
3 network-cont 1769399 1769399 0
Queue number: Mapped forwarding classes
0 best-effort
1 expedited-forwarding
2 assured-forwarding
3 network-control
Active alarms : None
Active defects : None
MAC statistics: Receive Transmit
Total octets 8511109371495 5757097345534
Total packets 1645955461 52362499
Unicast packets 1642723238 50037184
Broadcast packets 1363152 4595
Multicast packets 1869071 1769399
CRC/Align errors 0 0
FIFO errors 0 0
MAC control frames 0 0
MAC pause frames 0 0
Oversized frames 0
Jabber frames 0
Fragment frames 0
VLAN tagged frames 0
Code violations 0
Filter statistics:
Input packet count 0
Input packet rejects 0
Input DA rejects 0
Input SA rejects 0
Output packet count 0
Output packet pad count 0
Output packet error count 0
CAM destination filters: 1, CAM source filters: 0
Autonegotiation information:
Negotiation status: Complete
Link partner:
Link mode: Full-duplex, Flow control: None, Remote fault: OK, Link partner Speed: 1000 Mbps
Local resolution:
Flow control: None, Remote fault: Link OK
Packet Forwarding Engine configuration:
Destination slot: 0
CoS information:
Direction : Output
CoS transmit queue Bandwidth Buffer Priority Limit
% bps % usec
0 best-effort 95 950000000 95 0 low none
3 network-control 5 50000000 5 0 low none
Interface transmit statistics: Disabled
Logical interface ge-0/0/0.0 (Index 79) (SNMP ifIndex 512) (Generation 144)
Flags: SNMP-Traps 0x0 Encapsulation: ENET2
Traffic statistics:
Input bytes : 8511109371495
Output bytes : 5757226511661
Input packets: 1645955461
Output packets: 54131898
Local statistics:
Input bytes : 0
Output bytes : 129166127
Input packets: 0
Output packets: 1769399
Transit statistics:
Input bytes : 8511109371495 5197400 bps
Output bytes : 5757097345534 10281600 bps
Input packets: 1645955461 1423 pps
Output packets: 52362499 902 pps
Security: Zone: Null
Flow Statistics :
Flow Input statistics :
Self packets : 0
ICMP packets : 0
VPN packets : 0
Multicast packets : 0
Bytes permitted by policy : 0
Connections established : 0
Flow Output statistics:
Multicast packets : 0
Bytes permitted by policy : 0
Flow error statistics (Packets dropped due to):
Address spoofing: 0
Authentication failed: 0
Incoming NAT errors: 0
Invalid zone received packet: 0
Multiple user authentications: 0
Multiple incoming NAT: 0
No parent for a gate: 0
No one interested in self packets: 0
No minor session: 0
No more sessions: 0
No NAT gate: 0
No route present: 0
No SA for incoming SPI: 0
No tunnel found: 0
No session for a gate: 0
No zone or NULL zone binding 0
Policy denied: 0
Security association not active: 0
TCP sequence number out of window: 0
Syn-attack protection: 0
User authentication errors: 0
Protocol eth-switch, MTU: 0, Generation: 158, Route table: 0
Flags: Is-Primary, Trunk-Mode
SRX - interface vlan.551
admin@"SRX"# run show interfaces vlan.551 extensive
Logical interface vlan.551 (Index 91) (SNMP ifIndex 535) (Generation 158)
Flags: SNMP-Traps 0x0 VLAN-Tag [ 0x8100.551 ] Encapsulation: ENET2
Bandwidth: 0
Traffic statistics:
Input bytes : 6835490047251
Output bytes : 4469740006029
Input packets: 8153298551
Output packets: 10030630940
Local statistics:
Input bytes : 15745185
Output bytes : 25891389
Input packets: 271821
Output packets: 338622
Transit statistics:
Input bytes : 6835474302066 0 bps
Output bytes : 4469714114640 0 bps
Input packets: 8153026730 0 pps
Output packets: 10030292318 0 pps
Security: Zone: Null
Flow Statistics :
Flow Input statistics :
Self packets : 0
ICMP packets : 0
VPN packets : 0
Multicast packets : 0
Bytes permitted by policy : 0
Connections established : 0
Flow Output statistics:
Multicast packets : 0
Bytes permitted by policy : 0
Flow error statistics (Packets dropped due to):
Address spoofing: 0
Authentication failed: 0
Incoming NAT errors: 0
Invalid zone received packet: 0
Multiple user authentications: 0
Multiple incoming NAT: 0
No parent for a gate: 0
No one interested in self packets: 0
No minor session: 0
No more sessions: 0
No NAT gate: 0
No route present: 0
No SA for incoming SPI: 0
No tunnel found: 0
No session for a gate: 0
No zone or NULL zone binding 0
Policy denied: 0
Security association not active: 0
TCP sequence number out of window: 0
Syn-attack protection: 0
User authentication errors: 0
Protocol inet, MTU: 1500, Generation: 175, Route table: 5
Flags: Sendbcast-pkt-to-re, Is-Primary
Addresses, Flags: Is-Default Is-Preferred Is-Primary
Destination: 10.0.5.8/29, Local: 10.0.5.11, Broadcast: 10.0.5.15, Generation: 180
I will try to implement BFD, it could help to see more details.
Again, thank you for your time.
Regards.