# Interface Attachment Resources Overview

JunosE Software allocates interface attachment resources when policies are attached to interfaces—when you attach a policy to an interface, the policy consumes one of the interface’s attachment resources. Each interface has two attachment resource pools. IP and IPv6 policy attachments are allocated from the interface’s IP attachment resource pool; all other attachments are allocated from the interface’s layer 2 attachment resource pool.

- The type of line module determines the number of policies attachments supported by interfaces. See ERX Module Guide, Appendix A, Module Protocol Support for more information about supported line modules. See E120 and E320 Module Guide, Appendix A, IOA Protocol Support for information about the modules that support BGP.
- On ASIC-based line modules (OC48/STM16, GE-2, and GE-HDE line modules), you can have a maximum of 8191 IP policy attachments and 8191 layer 2 policy attachments for ingress policies per forwarding controller, and 8191 IP policy attachments and 8191 layer 2 policy attachments for egress policies per forwarding controller.
- On FPGA-based line modules, you can have a maximum of 8191 IP policy attachments and 8191 layer 2 policy attachments per forwarding controller.