Technical Documentation
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GE-8 I/O Modules Overview
The ERX1440 and ERX310 routers both support the GE-8 I/O module. Other E Series routers do not support the GE-8 I/O module.
The GE-8 I/O module pairs with the GE-HDE line module to provide Gigabit Ethernet operation through eight line interfaces.
 | Note: The GE-8 I/O module has a logical port, numbered port 8, that is reserved for the hardware multicast packet replication feature. For more information, see JunosE Multicast Routing Configuration Guide . |
You can install the GE-HDE line module and its corresponding GE-8 I/O module in slot 1 or slot 2 of an ERX310 router or in any slot of an ERX1440 router.
The GE-8 I/O module can use either fiber-optic or copper SFPs. The I/O module accepts up to eight pairs (Tx/Rx) of LC-style fiber-optic connectors that support different optical modes and cabling distances. Alternatively, the I/O module supports up to eight pairs of copper SFPs.
Bandwidth and Line Rate Considerations
When the GE-HDE line module is installed in the ERX1440 router, it delivers full bandwidth of 4 Gbps per line module (2 Gbps at the ingress and 2 Gbps at the egress) only when installed in slot 2 or slot 4, and when the SRP-40G+ module is used in the router. When the module is installed in any other ERX1440 slot, it delivers a maximum bandwidth of 2 Gbps per line module (1 Gbps maximum at the ingress and 1 Gbps maximum at the egress). Therefore, of the maximum 96 possible ports for the module in an ERX1440 chassis (that is, eight ports in each of 12 slots), full bandwidth is delivered only on a maximum of 16 ports (those in slots 2 and 4).
When the GE-HDE line module is installed in either the ERX1440 or the ERX310 router and all ports are active, line rate performance is achieved only with packets that are 174 bytes or larger. The module might not achieve line rate with packets that are smaller than 174 bytes.
Table 1 lists the average data rate on the GE-HDE line module and GE-8 I/O module combination when installed in an ERX310 router or in slots 2 or 4 of an ERX1440 router.
Table 1: Average Data Rate for ERX310 router or in Slots 2 or 4 of an ERX1440 router
Port Combination | Average Data Rate per GE-8 I/O Module (> 174 Byte Packets) | Average Data Rate per GE-HDE Line Module |
|---|---|---|
Ports 1–8 | 250 Mbps per port | 250 Mbps per port |
Any four ports | 500 Mbps per port | 500 Mbps per port |
Any two ports | 1 Gbps per port | 1 Gbps per port |
Table 2 lists the average data rate on the GE-HDE line module and GE-8 I/O module combination when installed in all other slots on the ERX1440.
Table 2: Average Data Rate When Installed in All Other Slots on an ERX1440 router
Port Combination | Average Data Rate per GE-8 I/O Module (> 174 Byte Packets) | Average Data Rate per GE-HDE Line Module |
|---|---|---|
Ports 1–8 | 125 Mbps per port | 125 Mbps per port |
Any four ports | 250 Mbps per port | 250 Mbps per port |
Any two ports | 500 Mbps per port | 500 Mbps per port |
Managing High-Density Ethernet
The overall data rate for the GE-HDE line module is 2 Gbps; therefore, the I/O module becomes highly oversubscribed because of the wire rate of the line module. The data rate of the GE-8 I/O module is limited with larger frames, and the packet rate is limited with smaller frames.
Currently, flow control using MAC pause frames is disabled on the GE-8 I/O module. The I/O module does not transmit or receive pause frames.
For more information about high-density Ethernet, see High-Density Ethernet Overview.
