150-820 Question #159: Real Exam Question with Answer & Explanation

You added a new Brocade VDX 6740 to an existing Brocade VCS Fabric in your data center. You connected the VDX 6740 to ports 3/0/11 and 3/0/12 on the existing fabric. After the switch boots, you realize it does not join the fabric. You examine the ISL status on the fabric as shown in the exhibit. sw0(conf-if-te-3/0/19)# do sh fabric islport Name: sw0 Type: 95.2 State: Online Role: Fabric Principal VCS Id: 1 Config Mode:Distributed Rbridge-id: 3 WWN: 10:00:00:05:33:46:71:61 FCF MAC: 00:05:33:46:71:61 Index Interface State Operational State =================================================================== 0 Te 3/0/1 Down 1 Te 3/0/2 Down 2 Te 3/0/3 Down 3 Te 3/0/4 Down 4 Te 3/0/5 Down 5 Te 3/0/6 Down 6 Te 3/0/7 Down 7 Te 3/0/8 Up ISL 10:00:00:05:33:5c:e1:5a "sw0" (downstream)(Trunk Primary) 8 Te 3/0/9 Up ISL (Trunk port, Primary is 3/0/8 ) 9 Te 3/0/10 Down 10 Te 3/0/11 Up ISL (Trunk port, Primary is 3/0/12 ) 11 Te 3/0/12 Up ISL segmented,(ESC mismatch, Config Mode)(Trunk Primary) 12 Te 3/0/13 Down 13 Te 3/0/14 Down 14 Te 3/0/15 Down 15 Te 3/0/16 Down 16 Te 3/0/17 Down 17 Te 3/0/18 Down 18 Te 3/0/19 Down 19 Te 3/0/20 Down 20 Te 3/0/21 Down 21 Te 3/0/22 Down 22 Te 3/0/23 Down 23 Te 3/0/24 Down What is causing the problem?