Graphcore IPU-POD128, Build And Test Manual, Page: 35 / 113

IPU-POD128 build and test guide
3.6.1 IPU-M2000 to IPU-M2000 IPU-Link connectivity (OSFP)
There are eight OSFP IPU-Link ports on the right side of each IPU-M2000. Using the supplied 60x 0.3M OSFP
cables, and starting at IPU-M2000 #1 (bottom-most IPU-M2000 in the rack), link the top row of four ports (5-8)
to the bottom row of four ports (1-4) in the IPU-M2000 that is installed directly above (see Fig. 3.40 and Table 3.2
below). This applies to all IPU-M2000s except for the top row (5-8) of the top-most IPU-M2000 (#16) and the
bottom row (1-4) of the bottom-most IPU-M2000 (#1), which are connected together using the 1m OSFP cables.
Fig. 3.40: IPU-M2000 IPU-Link port numbering and IPU-Link cables
Before attempting to install the OSFP cables, it is beneficial to manipulate the cable to form a tight loop ( Fig.
3.41 ). During manufacture and shipping, the cables can form quite a stiff shape, so manipulating the cables before
installing them reduces stresses on the socket during install.
Fig. 3.41: Manipulating IPU-Link cables
After installing a cable, pull gently on the black cable ( Fig. 3.42 ) to ensure the plugs are firm in the sockets on the
IPU-M2000.
Version: latest (2021-11-25) 31