> # Configuring B Ports

> While E ports typically interconnect Fibre Channel switches, some SAN extender devices, such as Cisco’s PA-FC-1G Fibre Channel port adapter and the SN 5428-2 storage router, implement a bridge port model to connect geographically dispersed fabrics. This model uses B port as described in the T11 Standard FC-BB-2. B ports bridge Fibre Channel traffic from a local E port to a remote E port without participating in fabric-related activities such as principal switch election, domain ID assignment, and Fibre Channel fabric shortest path first (FSPF) routing. The IPS module and MPS-14/2 module support FCIP links that originate from a B port SAN extender device by implementing the B access ISL protocol on a Gigabit Ethernet interface.

> When an FCIP peer is a SAN extender device that only supports Fibre Channel B ports, you need to enable the B port mode for the FCIP link. When a B port is enabled, the E port functionality is also enabled and they coexist. If the B port is disabled, the E port functionality remains enabled.

> ## Detailed Steps

> To enable B port mode, follow these steps:

> 1. Choose ISLs > FCIP from the Physical Attributes pane.

> You see the FCIP profiles and links in the Information pane.

> From Device Manager, choose IP > FCIP. You see the FCIP dialog box.

> 1. Click the Tunnels tab.

> You see the FCIP link information.

> 2. Click the Create Row icon in DCNM-SAN or the Create button in Device Manager.

> You see the FCIP Tunnels dialog box.

> 3. Set the ProfileID and TunnelID fields.
> 4. Set the RemoteIPAddress and RemoteTCPPort fields for the peer IP address you are configuring.
> 5. Check the PassiveMode check box if you do not want this end of the link to initiate a TCP connection.
> 6. (Optional) Set the NumTCPCon field to the number of TCP connections from this FCIP link.
> 7. Check the Enable check box in the B Port section of the dialog box and optionally check the KeepAlive check box if you want a response sent to an ELS Echo frame received from the FCIP peer.
> 8. (Optional) Set the other fields in this dialog box and click Create to create this FCIP link.

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