This value is the extended burst limit in bytes, the larger burst size beyond which all traffic is treated as exceeding the rate limit, giving a second, more generous burst tolerance above the normal limit. Admins use it to allow occasional bigger bursts more headroom before the exceed action, such as drop, applies to every packet. For example, setting a high snPortCARExtLimit lets a rule tolerate a large one-time burst, like a backup job, before strict rate limiting kicks in.