Fibre Channel Nat And Phantom Domains; Setting Up The Fc-Fc Routing Service - HP AA979A - StorageWorks SAN Switch 2/8V Administrator's Manual

Fibre Channel NAT and phantom domains

Within an edge fabric or across a backbone fabric, the standard Fibre Channel FSPF protocol determines
how frames are routed from the source Fibre Channel (FC) device to the destination FC device. The source
or destination device can be a proxy device. When frames traverse the fabric through a 400 MP Router or
4/256 SAN Director in the backbone (BB), the frames are routed to another EX_Port or VEX_Port.
Fibre Channel fabrics require that all ports (EX_Ports or VEX_Ports) be identified by a unique PID. In a
single fabric, FC protocol guarantees that domain IDs are unique, and so a PID formed by a domain ID
and area ID is unique within a fabric. However, the domain IDs and PIDs in one fabric might be duplicated
within another fabric, just as IP addresses unique to one private network are likely to be duplicated within
another private network.
In an IP network, a network router can maintain network address translation (NAT) tables to replace private
network addresses with public addresses when a packet is routed out of the private network, and replace
public addresses with private addresses when a packet is routed from the public network to the private
network. The Fibre Channel routing equivalent to this IP-NAT is the Fibre Channel network address
translation (FC-NAT). Using FC-NAT, the proxy devices in a fabric can have different PIDs than the real
devices that they represent, allowing the proxy devices to have appropriate PIDs for the address space of
their corresponding fabric.
All EX_Ports connected to same edge fabric from one physical FC router present a single front phantom
domain and one additional translate (xlate) phantom domain for each edge fabric accessed through it. All
EX_Ports and VEX_Ports connected to an edge fabric use the same xlate domain ID number for an
imported edge fabric; this value persists across switch reboots and fabric reconfigurations. Xlate domains
are presented as being connected topologically behind one or more front domains; each FC-Router
presents one front domain to edge fabric. This allows redundant paths to remote fabrics to present
redundant paths to proxy devices to an edge fabric.
Phantom domains are like logical switches that appear to be connected to an edge fabric through the front
domains that are presented by EX_Ports and/or VEX_Ports. The combination of front domains and xlate
domains allows routing around path failures, including path failures through the routers. The multiple paths
to an xlate domain provide additional bandwidth and redundancy.
There are some differences in how the xlate domain is presented in the BB. The BB xlate domains are
topologically connected to FC routers and participate in FC-Protocol in BB. Front domains are not needed
in the BB. As in the case of xlate domain in edge fabric, BB xlate domains provide additional bandwidth
and redundancy by being able to present itself being connected to single or multiple FC routers with each
FC router capable of connecting multiple IFLs to edge fabrics.

Setting up the FC-FC routing service

To set up the FC-FC Routing Service, perform the following tasks:
1. "Performing verification
2. "Assigning Backbone Fabric IDs"
3. "Configuring FCIP tunnels (optional)" on page -209
4. "Configuring FC-FC routing to work with Secure Fabric OS (optional)" on page -209
5. "Configuring an interfabric link" on page -21 1
6. "FC router port cost (optional)" on page -219
7. "EX_Port frame trunking (optional)" on page -222
8. "Configuring LSANs and zoning" on page -216
See "Configuring
206 Using the FC-FC routing service
checks" next
on page 1 1- 1 3
Directors" on page 207 for more details about configuration options.