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Implementing SAN Internetworking Solutions
4
SAN Routing also streamlines SAN connectivity by eliminating
network address issues associated with duplicate Domain_IDs.
Because fabric elements and devices at either end of an iFCP
connection remain in separate mSANs, address conflicts between the
mSANs do not occur. SAN Routing provides address translation
(through FC_NAT) for zoned devices with authorization to
communicate across the network.
iSAN Routing Domain
The routing domain with proxy Domain_ID 31 (hexadecimal 7F)
represents devices that are directly attached to SAN router Fibre
Channel ports or connected through an iFCP link. The router reserves
this domain to enable routing between iSANs. This routing domain is
visible to all directors and switches in each router-attached mSAN
and appears as a virtual switch (with Domain_ID 31) to SAN
management applications.
NOTE: A reserved routing domain with proxy Domain_ID 30
(hexadecimal 7E) enables mSAN routing.
When communicating with directors and switches in a specific fabric,
SAN routers advertise devices associated with routing domains 30
and 31 as being directly attached to the domain, even though the
devices are physically attached to a separate fabric or mSAN. Proxy
Domain_ID 31 (remote mSAN over iSAN) is an internal router
domain connected behind proxy Domain_ID 30 (fabric over mSAN).
Therefore, if a problem occurs and there is no connectivity to routing
domain 30 (hexadecimal 7E), then there is also no connectivity to
routing domain 31 (hexadecimal 7F).
IRL Optimization
TCP is a resilient protocol that retransmits lost packets, reorders
out-of-order packets, detects duplicate packets, and provides flow
control mechanisms. The protocol is therefore appropriate for iFCP
connectivity over extended-distance links. However, additional
optimization is usually required to transport storage traffic effectively
across iFCP links. These optimization methods include:
Implementing SAN Internetworking Solutions
4-25
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