# IOA Slot Combinations

Depending on the software release and IOA type, you must install IOAs in certain slots and bays combined with other IOAs in the same slot:

- You must insert some IOAs only in the upper bay or right bay (Adapter 0) of each IOA module slot. If you insert one of these IOAs into a lower bay or left bay (Adapter 1) slot, the line module diagnostics fail, an error message states that the bottom slot is not supported for the currently installed software release, and the slot is disabled.
- If you insert an unrecognized IOA, such as an IOA that is not supported by a particular software release, the line module diagnostics fail, an error is generated, and the slot is disabled.
- If you remove an IOA and replace it with a different IOA in the same slot, an error message states the mismatch and the slot is disabled.
- Full-height IOAs take up the entire slot (both Adapter 0 and Adapter 1).

For information about working with modules and IOAs, see JunosE System Basics Configuration Guide, Chapter 6, Managing Modules. See Table 29 for currently available IOAs and the bays in which you may insert them.

Table 29: IOA Locations and Combinations

IOA | Upper/Right Bay (Adapter 0) | Lower/Left Bay (Adapter 1) | Both Bays Concurrently | Combined with Other IOAs in Same Slot | Hot-Swapping Support
--- | --- | --- | --- | --- | ---
ES2-S1 GE-4 | Yes | Yes | No | No | Yes
ES2-S1 GE-8 | Yes | Yes | Yes | Yes (GE-8 when paired with ES2 4G LM or ES2 10G LM; GE-8, OC3/STM1, and OC12/STM4 IOAs when paired with ES2 4G LM) | Yes
ES2-S3 GE-20 | Yes (Full-height IOA) | Not applicable | Not applicable | Not applicable | No
ES2-S1 10GE | Yes (Full-height IOA) | Not applicable | Not applicable | Not applicable | No
ES2-S2 10GE PR | Yes (Full-height IOA) | Not applicable | Not applicable | Not applicable | No
ES2-S1 OC3-8 STM1 ATM | Yes | Yes | Yes | Yes (GE-8, OC3/STM1, and OC12/STM4 IOAs only) | Yes
ES2-S1 OC12-2 STM4 ATM | Yes | Yes | Yes | Yes (GE-8, OC3/STM1, and OC12/STM4 IOAs only) | Yes
ES2-S1 OC12-2 STM4 POS | Yes | Yes | Yes | Yes (GE-8, OC3/STM1, and OC12/STM4 IOAs only) | Yes
ES2-S1 OC48 STM16 POS | Yes | Yes | No | No | Yes
ES2-S1 SERVICE | Yes (Full-height IOA) | Not applicable | Not applicable | Not applicable | No
ES2-S1 REDUND | Yes (Full-height IOA; slots 0 and 11 only) | Not applicable | Not applicable | Not applicable | No