Brocade: Configuring ports to work over long distances

When spacing switches over distances exceeding 5 km, it is necessary to configure the operation of E-ports in the "Long-Distance" mode. To do this, use the "portcfglongdistance" command:

portcfglongdistance [slot/]port distance_level vc_translation_link_init -distance desired_distance

where distance_level is the "Long-Distance" mode of operation, canbe:
L0 (default normal mode with limits of 5 km for 2G, 2 km for 4G, 1 km for 8G and above);
LE (extended mode for distances of 5-10 km, does not require an additional license);
LD (dynamic mode, calculates the number of buffer credits based on self-made measurements of the line length);
LS (static mode - the switch calculates the number of buffer credits from the distance value set by the user).
vc_translation_link_init - "fill words", when set to IDLE(0) mode, the link uses IDLE fill words. When set to ARB (1), FF is used to reduce electrical noise in copper equipment.
desired_distance - distance between switches in kilometers.

For example, set "Long-Distance" on port 11 in static mode with the fill word ARB and an estimated distance of 60 km:

portcfglongdistance 11 LS 1 -distance 60

Using the "portbuffercalc" command, we can pre-calculate how many buffer credits will be needed on our equipment. Using the input data from the previous example, we calculate for a speed of 32G:

portbuffercalc 11 -speed 32 -distance 60 -framesize 2048
966 buffers required for 60km at 32G and framesize of 2048bytes

Also, for correct operation, it may be necessary to change the following parameters through the "configure" interactive command in the "disabled" state of the switch:
R_A_TOV - Resource Allocation Time Out Value (default 10000) can be from E_D_TOV*2 to 120000;
E_D_TOV - Error Detect Time Out Value (default 2000) can be from 1000 to R_A_TOV/2;
WAN_TOV - Wide-Area Network TimeOut Value (default 0) can be from 0 to R_A_TOV/4;
MAX_HOPS - Maximum number of hops in the region before a BPDU is discarded (default 7) can be from 7 to 19.