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Data Center High Availability Clusters Design Guide
OL-12518-01
Chapter 4 FCIP over IP/MPLS Core
Testing Scenarios and Results
Figure 4-11 Cisco MDS 9216i Connection to GSR MPLS Core
Configuring TCP Parameters on CPE (Cisco MDS 9216)
A simple ping command from the Cisco MDS 9000 CLI, provides the RTT between the two IP
addresses. RTT is specified as part of the following configuration command. It may be specified in either
microseconds (-us suffix) or in milliseconds (-ms suffix).
The following command shows RTT set for 20 milliseconds:
tcp max-bandwidth-mbps XXXX min-available-bandwidth-mbps xxxx round-trip-time-ms 20
Configuring the MTU
The MTU is the maximum payload the Gigabit Ethernet interface will handle. The default MTU for the
Gigabit Ethernet interface is 1500, which does not include Ethernet headers and trailers.
The maximum Fibre Channel frame size including headers and trailers is 2148 bytes. Fibre Channel data
frames in typical storage applications have a payload of 2048 bytes plus 36 bytes in headers and trailers,
leaving a frame size of 2084 bytes. The Cisco MDS 9000 optionally adds two headers to the Fibre
Channel frame. The EISL header is an eight-byte field carrying VSAN tagging information that is only
added if the FCIP interface is defined as a TE_Port. If the EISL header is present, it is located
immediately after the four-byte start-of-frame (SOF) sequence. There is also an optional header (up to
16 bytes) that is reserved for future use.
With the inclusion of EISL and optional headers, the maximum Fibre Channel frame size is 2172 bytes.
An FCIP packet over Ethernet includes 94 to 98 bytes of headers, plus a four-byte Ethernet CRC32
trailer. When carrying the maximum size Fibre Channel frame, the maximum Ethernet frame size is 2274
bytes (2172 + 98 + 4 = 2274).
GSR 12410
Provider Core
GSR 12410
Provider Core
GSR 12410
Provider Core
GSR 12410
PE
GSR 12410
PE
132430
Gigabit Ethernet/POS/
Serial/DS3/DS1
Gigabit Ethernet/POS/
Serial/DS3/DS1
10.10.10.1
11.11.11.1