Switch Stacking

Benefits: MEC and centrolized & simplied management

MEC (Multi-chassis EtherChannel)

• It also known as Multi-chassis Link Aggregation Group (MLAG or MC-LAG).
• MEC is a Layer 2 multi-path technology and a type of EtherChannel which allows a switch (S1) terminates an EtherChannel across other two physical switches (S2 and S3).

Teches of Switch Stacking

Technology \ Params	VSS (Virtual Switching System)	StackWise	StackWise Virtual
# of Stacked Switches	2	Up to 8	2
Interface Type	Ethernet	Stack ports	Ethernet
Interface Bandwith	10G or 40G	Up to terabits	10G, 25G, 40G, or 100G
# of Interfaces	1-8	2 per switch	1-8
Cables	Ethernet or fiber	Stack cable	Ethernet or fiber
Cable Length	Up to kilometers fiber	0.5m, 1m, 3m	Up to kilometers fiber
Link Type	VSL (Virtual Switch Link)	Stacking Link	SVL (StackWise Virtual Link)
Link Protocols	LMP & RRP	SDP	LMP & SDP
Traffic on Links	VSS control & data	Control & data	SVL control & data
Links Topology		Ring
Support Switches	Catalyst 4500/6500/6800	Catalyst 3750/3850, 9200/9300	Catalyst 9400/9500/9600
Member Roles	Active & Standby	Active, Standby, & Members	Active & Standby
Working Mode	RPR or NSF/SSO

RPR - Router-Processor Redundancy
NSF/SSO - Non-Stop Forwarding/Stateful Switchover
LMP - Link Management Protocol
RRP - Role Resolution Protocol
SDP of StackWise- Stack Discovery Protocol
SDP of StackWise Virtual - StackWise Discovery Protocol

Ring Topology

A ring topology connecting four switches, SW1, SW2, SW3 and SW4, logically looks like below:

 .---> sp2:=SW1=:sp1 ------> sp2:=SW2=:sp1 ----.
|                                               |
 `---- sp1:=SW4=:sp2 ------> sp1:=SW3=:sp2 <---`

sp: Stack Port