Owner's manual

HP ProCurve Switch 4000M / 8000M / 2424M / 1600M Reviewer’s Guide

Redundancy is also provided by Switch Meshing. If one of the links fails between switches, traffic is

redirected through another path, if available. The switchover time of typically less than 1 second is very

fast. Very robust high availability solutions can be implemented with a switch mesh.

Switch Meshing allows multiple HP ProCurve Switches 4000M/8000M/2424M/1600M to form a virtual

backplane between the switches, allowing reliable high port density environments to be made

inexpensively.

Up to 12 switches can participate in a Switch Meshing domain. Multiple Switch Meshing domains can

exist in a single LAN environment, but not within the same switch. Switch Meshing works well for local

environments as large as 5,000 nodes.

Routing switches and routers use a similar technique through routing protocols such as RIP, OSPF or

BGP. But Switch Meshing is an improvement over these routing protocols because:

• The path decision in HP’s Switch Meshing is determined by dynamically determined latency

through the switches. Routing protocols do not take latency into account, only path costs based

on link speeds (OSPF) or simply the lowest number of router hops (RIP).

• Switch Meshing works for all layer 3 protocols, as well as non-routable protocols such as DEC

LAT or NETBios, because path specification is performed using layer 2 MAC addresses. Routing

switches can only specify paths based on supported Layer 3 protocols, (usually IP, sometimes

IPX and rarely AppleTalk), otherwise they must simply bridge the packet and use Spanning

Tree.

• Configuration of Switch Meshing is trivial. Specifying which ports are part of the Switch

Meshing domain is all that is needed. The switch takes care of the rest. This is in sharp contrast

to configuration of routing protocols which can be challenging.

• Convergence time (time to recover from a lost link) is fast - typically less than one second. This

is much faster than RIP and faster or on par with OSPF using triggered updates.

• Unlike a router, no packet modification is required as it travels through the switch, keeping the

latency through ProCurve switches lower than routing switches.

A white paper with more details on Switch Meshing can be found in the technical library on HP’s

networking web site at

http://www.hp.com/rnd/products/solutions/techlib/techlib.htm

2.7 QoS Features

2.7.1 Incoming IEEE 802.1p Priority Tag Support

IEEE 802.1p packet tagging supports both designation of VLAN membership (see the VLAN section

below) and packet priority (up to 8 levels). The architecture of the HP ProCurve

Switches 4000M/8000M/2424M/1600M support two levels of priority through different port buffer

queues, regular and high. If a tagged packet with the priority field value up to 3 comes into these

switches, it will be put into the regular priority queue; at a priority value of 3 and above, the packet is

put into the high priority queue. This allows the 4000M / 8000M / 2424M / 1600M to be responsive to

time-sensitive applications that use the priority field in packet tagging for their data streams.

IGMP packets coming through the switch can be automatically assigned to the high priority queue

through a single item in the switch configuration.

2.7.2 In-Switch 802.1p Tagging

Data networks are starting to carry types of data streams that have differing priorities in how they

should be handled. The Switch 8000M / 1600M

can be configured to give a particular priority to a

packet based on:

Starting with firmware revision C.07.23. Older revisions can be updated at no charge through the HP ProCurve web site.