I have inherited an oversubscribed WAN that needs help. An HQ site has a DS3 with about 90 remote sites each with T1s. Each site taps an SP MPLS PE over HDLC but we are not running MPLS ourselves or running VPNs through the SP. It only provides the peer-to-peer behavior for the voice.
Initially implemented CBTS at 1536k per site on DS3 outbound. Yes, 90 classes defining each site and shape average for the class. The shaping policy calls another policy for CBWFQ/LLQ. No traffic shaping outbound on the remote routers (yet). Shape average prevents me from congesting the remote links in the SP network but will still permit the network to send more traffic to the DS3 outbound than it can handle. Even with the CBWFQ/LLQ parameters, voice and critical apps have suffered during a couple of events where updates were pushed to multiple sites simultaneously and taxed the DS3. (I don't control the sysadmins and their policies so I have to try to protect my network from them.)
Could use shape peak but fear the effects on voice. It also seriously trims down the BW available to use for CBWFQ/LLQ.
The docs and SRNDs do a great job of dealing with shaping on oversubscribed networks and CBWFQ/LLQ on converged networks but fail miserably at bringing to two situations together. Looking for recommendations and best practices for such a scenario to bring some immediate stability.
Tyler West, CCNP
Simple solution to bandwidth management to 3845, assuming you're routing, weigh paths such that one is active and other is standby (outbound). Then you can both insure only 45 Mbps sent to 3845 and still have fail-over redundancy.
Whether to shape/queue directly on 6500 depends on what it supports. I know 6500s police and also know they often have multiple queues per port, but unsure typical LAN ports support shaping. Reading such as:
Q. Is traffic shaping supported on the Catalyst 6500 (Cat6K) Switch?
A. Traffic shaping is only supported on certain WAN modules for the Catalyst 6500/7600 Series, such as the Optical Services Modules (OSMs) and FlexWAN modules. Refer to Cisco 7600 Series Router Module Configuration Notes for further information.
Would lead me to believe, they might not.
If they don't, a pair of 2960-8TC-Ls, one per Ethernet link, along with active/standby link usage, might provide the aggregate DS3 queue management.
Without an upstream shaper, you would assign LLQ bandwidth to support your expected aggregate. You would shape for each at its bandwidth, less what you want to set aside for voice on that spoke. Going too low at the parent level LLQ bandwidth is bad; too high not a problem. Going too low at spoke level, also bad; too high will reduce available bandwidth for other apps, even when not being used by voice.
Unclear why you're shaping (full?) T1s at 360 Kbps. Why are you not shaping for 1.5 Mbps?
Shape peaking is an issue, since it, along with larger Tcs, allows for possible large packet bursts. If there's FIFO queuing, such bursts can cause highly variable performance for time sensitive traffic, such as VoIP. (In fact, when dealing with voice, it's often a good idea to reduce an interface's TX [FIFO] buffer size, for the same reason.)
To summarize what I'm suggesting, on a 2960 use "srr-queue bandwidth limit (40 to 45)" on 100 Mbps port. Configure "priority-queue out" and place real-time traffic, such as voice, into Q1. Configure something like "srr-queue bandwidth share 100 1 75 224". Place critical apps in Q4, BE in Q3, background in Q1. This insures, at the DS3 interface level, traffic is prioritized as we want.
On the 3845, continue to do what your doing. Something like (with HQF):
priority percent 30
bandwidth percent 89
bandwidth percent 1
bandwidth percent 10
shape average 15000000