SRX Services Gateway
SRX Services Gateway

SRX DS3 fails to come up, J-Series works

‎07-10-2015 12:44 PM

We have an issue that I am hoping someone else on these forums has seen before. We are moving from J-Series to SRX550, and our T3/DS3 links are not coming up. We triple-checked the configuration (and yes JTAC is involved), and it matches (pasted below).


The symptom is that we see physical link up and logical link down. We get framing errors, LOS and LOF. Put the J-Series back in place, everything comes right up; put the SRX550 in, link fails to establish. We see packets going out but no packets coming in.


It's maddening. Since it happened with two different ISPs on two different links, I am really hoping someone has seen this before and has the answer. We're with ATAC and the ISPs, but if we can short-cut and know "you should take a look at THIS," it'd help a ton. I'll bribe ya, if you have something good to share that helps us solve, there's definitely food and beer coming your way :).


t3-3/0/0 {
   encapsulation ppp;
   t3-options {
      compatibility-mode digital-link;
      fcs 32;
   unit 0 {
      description "A T3 circuit";
      bandwidth 45m;
      family inet {



SRX Services Gateway
Accepted by topic author tbehrens
‎08-26-2015 01:27 AM

Re: SRX DS3 fails to come up, J-Series works

‎07-16-2015 10:10 PM

Hi ,


Try disabling payload scrambling under e3-options if you are using digital-link compatibility mode (on both sides)


try using kentrox subrate 48

this seems to be related to inter-operability between SRX and other devices.




e3-options {
    compatibility-mode kentrox subrate 48;
    inactive: payload-scrambler;
    fcs 32;

We are trying to identify root cause.





Please Mark My Solution Accepted if you think it helped!
SRX Services Gateway

Re: SRX DS3 fails to come up, J-Series works

‎07-17-2015 06:22 AM

Right on. We disabled payload-scrambler on both sides of the link yesterday and it resolved the problem. SRX550 on JunOS 12.1X44-D45 on one end and M120 with unknown version of JunOS on the carrier end.


All of the other slight mismatches on the link - compatibility mode we didn't need, short link mode set when we really should have set long, internal clocking on both ends - we did not (need to) touch. Once scrambling was disabled, the link came up immediately.


PM me your home address please so we can send you a gift card to a steak house. A promise is a promise :).