InterSwitch Trunk (IST) is one or more parallel point-to-point links (
Link aggregation
In computer networking, link aggregation is the combining ( aggregating) of multiple network connections in parallel by any of several methods, in order to increase throughput beyond what a single connection could sustain, to provide redundan ...
) that connect two switches together to create a single logical switch. The IST allows the two switches to share addressing information, forwarding tables, and state information, permitting rapid (less than one second) fault detection and forwarding path modification. The link may have different names depending on the vendor. For example, Brocade calls this an Inter-Chassis Link (ICL). Cisco calls this a VSL (Virtual Switch Link).
Edge switches, servers or PCs see the two aggregate switches as one large switch. This allows any vendor's equipment configured to use the IEEE 802.3ad static link aggregation protocol to connect to both switches and take advantage of load balancing, redundant connections.
The IST protocol was developed by
Nortel
Nortel Networks Corporation (Nortel), formerly Northern Telecom Limited, was a Canadian multinational telecommunications and data networking equipment manufacturer headquartered in Ottawa, Ontario, Canada. It was founded in Montreal, Quebec, ...
(now acquired by
Avaya
Avaya Holdings Corp., often shortened to Avaya (), is an American multinational technology company headquartered in Durham, North Carolina, that provides cloud communications and workstream collaboration services. The company's platform inclu ...
, which is now acquired by
Extreme Networks
Extreme Networks is an American networking company based in San Jose, California. Extreme Networks designs, develops, and manufactures wired and wireless network infrastructure equipment and develops the software for network management, policy, a ...
) to enhance the capabilities of
Link aggregation
In computer networking, link aggregation is the combining ( aggregating) of multiple network connections in parallel by any of several methods, in order to increase throughput beyond what a single connection could sustain, to provide redundan ...
, and is required to be configured prior to configuring the
SMLT
Multi-link trunking (MLT) is a link aggregation technology developed at Nortel in 1999. It allows grouping several physical Ethernet links into one logical Ethernet link to provide fault-tolerance and high-speed links between routers, switches, a ...
,
DSMLT
Multi-link trunking (MLT) is a link aggregation technology developed at Nortel in 1999. It allows grouping several physical Ethernet links into one logical Ethernet link to provide fault-tolerance and high-speed links between routers, switches, a ...
or
R-SMLT functions on the two aggregate (core, distribution, or access) switches. The edge equipment can be configured with any of the following;
Multi-Link Trunking (MLT),
DMLT, IEEE 802.3ad static link aggregation, IEEE 802.3ad Static Gigabit EtherChannel (GEC), IEEE 802.3ad Static Fast EtherChannel (FEC),
SMLT
Multi-link trunking (MLT) is a link aggregation technology developed at Nortel in 1999. It allows grouping several physical Ethernet links into one logical Ethernet link to provide fault-tolerance and high-speed links between routers, switches, a ...
,
DSMLT
Multi-link trunking (MLT) is a link aggregation technology developed at Nortel in 1999. It allows grouping several physical Ethernet links into one logical Ethernet link to provide fault-tolerance and high-speed links between routers, switches, a ...
, and other static link aggregation protocols.
Patent
United States Patent 7173934
Product support
IST is supported on Nortel's Routing Switch 1600, 5000, 8300,
ERS 8600,
MERS 8600 products and also on Avaya's Virtual Services Platform
VSP 7000 and
VSP 9000.
See also
*
Avaya
Avaya Holdings Corp., often shortened to Avaya (), is an American multinational technology company headquartered in Durham, North Carolina, that provides cloud communications and workstream collaboration services. The company's platform inclu ...
*
Avaya Government Solutions
References
External links
Designing a Resilient NetworkPassport 8600 Split Multi-Link TrunkingAlways on Networking
{{Avaya
Avaya
Ethernet
Link protocols
Network architecture
Network topology
Nortel protocols