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Ethernet Fabric (VDX, CNA)

Posts: 29
Registered: ‎12-02-2015

Number of switches in a fabric


Three data centers (each with a pair of VDX 6740s running NOS 6.0.2b) forming a fabric of six. The distance between data centers is ~5km (with no long-distance ISL configured).

Can I extend the fabric with more switches or I reached the limit? Don't know from where but I get the number six stuck in my head, perhaps it's from here:

Maximum of 8 ports per Brocade trunk and six Brocade trunks per ASIC (applies to VDX 67xxx and VDX 87xx switches).

Assuming that two 40GB ISL ports are used to interconnect VDXs in each datacenter, and one 10GB ISL port (per switch) to interconnect data centers, I guess I still have some space left for an extension?


Frequent Contributor
Posts: 80
Registered: ‎06-10-2009

Re: Number of switches in a fabric

You have reached a limit for what is termed a Metro VCS using standard distance ISLs.


If you need to increase the size of the VCS fabric itself then you could look at configuring some links for long distance ISLs, although these do have some restrictions relating to port groups and what you can then do with other ports within the same port group.  This is not particularly scalable as you are normally restricted to only 2 long distance ISLs on a VDX6740 (for example) although you can also have two additional standard ISLs (less than 2km) on the same platform.  Only 10G ports can be configured for long distance.


If you need more ports within some of the data centres then you can create local VCS clusters and then link these into the Metro VCS using vLAGs.  Each of the local (intra-DC VCS) would be separately managed.


NOS7.1.0 increased the scale of Metro VCS using standard distance ISLs so that you can now deploy up to ten nodes across five DCs.






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