150-820 · Question #203
You want to directly interconnect two Brocade VCS fabrics. Which two statements are true? (Choose two)
The correct answer is C. The VCS ID of both Brocade VCS fabrics should be different. D. Enabling Edge Loop Detection (ELD) will prevent a loop from accidently being created. See the full explanation below for the reasoning.
Question
You want to directly interconnect two Brocade VCS fabrics. Which two statements are true? (Choose two)
Options
- AThe VCS ID of both Brocade VCS fabrics should be the same.
- BEdge Loop Detection (ELD) is enabled globally per Brocade VDX.
- CThe VCS ID of both Brocade VCS fabrics should be different.
- DEnabling Edge Loop Detection (ELD) will prevent a loop from accidently being created.
How the community answered
(44 responses)- A14% (6)
- B7% (3)
- C80% (35)
Community Discussion
4
Viktor S.Jun 18, 2026C and D are correct. The VCS ID is what defines a fabric's identity, so if you connect two fabrics with the same VCS ID, the switches will attempt to merge into one fabric rather than interconnect as two distinct ones, which is not what you want here. Keep them different, and the fabrics stay separate while still being able to pass traffic between them. As for ELD, option B is trying to trick you with the word "globally" because ELD is configured per port, not globally per switch, so that statement is just wrong on the facts. Option D is the accurate one because ELD watches edge ports for loops and blocks the port if it detects one, which is exactly the safety net you need when you are linking two independent fabrics and want to avoid accidentally bridging them in a way that creates a loop. Stop memorizing C and D and actually think about what a VCS ID does and what ELD is designed to protect against, because that knowledge will save you in the field when something breaks.
Brenda K.Jun 22, 2026Grabbed C fast, but D tripped me up until I remembered ELD is your loop guard here.
Bao N.Jun 27, 2026C and D are the ones to lock in here, and D is the one people fumble because they assume ELD is just a nice-to-have rather than the actual loop prevention mechanism when you interconnect two separate fabrics. So when you say "directly interconnect," are you doing this over ISL ports between two distinct VCS domains, or are you thinking about merging them into one fabric, because that changes everything about why the IDs need to stay different?
Viktor S.Jun 29, 2026ELD being the loop prevention mechanism is correct, but worth being precise that it only matters when the fabrics stay as separate VCS domains joined by an ISL, because if you merge them into a single fabric the domain IDs become the critical piece and ELD's role shifts entirely.