From: Bob Sinclair (bob@bobsinclair.net)
Date: Thu Jun 07 2007 - 09:12:39 ART
thomas.rader@freesurf.ch wrote:
> Hello,
>
> Does anyone have a list of the differences in the features between the 3550 & 3560 switches?
>
Thomas,
You should be able to find posts on this topic in the archives, but here
is one list below. Szigeti has a good comparison in his book "End-to-End
QoS"
| Default trunking mode is dynamic auto instead of dynamic desirable
(no trunks by default)
| IPv6
7 Need to enable dual-stack sdm template
| Support for private vlans, in addition to protected ports
| Significant differences and enhancements to QoS
7 3550 dscp-mutation map applies per group of 12 ports;3560 per port
7 Can configure QoS on SVI interfaces as well as physical ports
o Enable VLANbased qos globally
o Use hierarchical policies that specify ports in CHILD policy
7 Bandwidth limit ports on egress
7 DSCP transparency to pass-through DSCP untouched
o No mls qos rewrite ip dscp
o Does NOT write CoS into frame on egress; ignores dscp-cos map
7 Inbound queueing
o Priority queue in is queue 2 by default; configurable but rarely needed
o Uses shared, not shaped queueing
7 Output Queueing
o Two modes: 1P3Q3T or 4Q3T
o Configure up to two queue-sets globally
' Sets up buffer depth and WTD thresholds
' Sh mls qos queue-set
7 Shows buffer weights, thresholds,
7 reserved and maximum
o Priority queue out is queue one instead of queue 4
' Configure on interface
o WTD weighted tail-drop congestion avoidance
' Three thresholds, two configurable
' Thresholds are 100% by default except Q2 which are 200%
o Shaped or Shared Round Robin Queueing
' Schedules packets rather than bytes (WRR)
' Shared just reserves; Shaped reserves and rate-limits
' Srr-queue bandwidth shape {shape | share | limit} on the interface to
set weights and limits.
o srr-queue map configured globally (unlike wrr map configured per
interface)
o Can map traffic to queue based on CoS or DSCP
o Default CoS > Queue mapping
' CoS 5 to queue 1
' CoS 0 and 1 to queue 2
' CoS 2 and 3 to queue 3
' CoS 4,6,7 to queue 4
o Queue buffers
' Mls qos queue-set output 1 buffers alloc1 alloc2 alloc3 alloc4
7 Sum of allocations must be 100 (%)
o Question: how many buffers in absolute terms?
' Sum of all buffers represents reserved pool, remaining buffers are
part of common pool
' Mls qos queue-set output 1 threshold 2 T1 T2 reserved maximum
7 Reserved-threshold: guaranteed buffers
7 Maximum-threshold: limit of borrowing from common pool up to 400%. If
set to 100%, then this queue cannot borrow buffers from other queues.
7 Show mls qos int statistics
o Packet counters for in/out and CoS/dscp values
o No monitor command
7 MQC
o Output policies are not supported
o 3560 does not support match VLAN directly on ports to match traffic
on a trunk. Does support match input-interface VLAN applied in a
hierarchical class-map to an SVI.
7 VLAN-based QoS
o Enable on physical port: Mls qos VLAN-based
o Create a hierarchical policy and apply to SVI: Child policy specifies
interfaces, parent attaches to SVI
--Bob Sinclair CCIE 10427 CCSI 30427 www.netmasterclass.net
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