Coupl of tests u may perform as follows...
1. physicially loop the ethernet cable between two ports of qfx 5110..
2. if the ports came up, then do similar exercise with cisco (i believe u seem to have done cisco part).
3. if port does not come up, check show chassis hardward and look out if the optics are unsupported on qfx.
4. if the ports came up ij 2nd step, proceed with connecting a cables between cisco and juniper. check the physical interface status. if using same cables, ports do not come up.
5. Then try fixing the speed, duplex and no autonegotiation on both sides.
1. physicially loop the ethernet cable between two ports of qfx 5110..
2. if the ports came up, then do similar exercise with cisco (i believe u seem to have done cisco part).
3. if port does not come up, check show chassis hardward and look out if the optics are unsupported on qfx.
4. if the ports came up ij 2nd step, proceed with connecting a cables between cisco and juniper. check the physical interface status. if using same cables, ports do not come up.
5. Then try fixing the speed, duplex and no autonegotiation on both sides.