file - mount Squashfs filesystem, little endian -

i have dumped part of file system of router file

cat /dev/mtdblock3 > /mnt/filesystem1 

here details of filesystem1

file ./filesystem1  filesystem1: squashfs filesystem, little endian, version 4.0, 3211714 bytes, 848 inodes, blocksize: 131072 bytes, created: wed apr 29 10:58:08 2015 

now mount ubuntu machine have created /mnt/squashfs/ dir im getting error

sudo mount -t squashfs ./filesystem1 /mnt/squashfs mount: wrong fs type, bad option, bad superblock on /dev/loop4,        missing codepage or helper program, or other error         in cases useful info found in syslog - try        dmesg | tail or so. 

how can mount filesystem1 ?