Hi, > On Dec 19, 2017, at 8:52 PM, James Jun <ja...@towardex.com> wrote: > > Hey, > > We have about 40 of ASR920's, mostly 24SZ-M and 24SZ-IM variants. We're > running mainly 03.16.04S and 03.16.05S.
… > For layer-2 services, we use LDP signalled L2CKT and VPLS. We tried testing > layer-3 use case, but last time we > tested (it was on early SW versions though.. like 3.14.x something), > control-plane protection like didn't even > work as we expected. Are you saying that whatever L3 issues you had have been resolved in the versions you cited above? > My overall experience with ASR920 are as follows. ... > The Bad Stuff: > - Weird behavior with 10G ports and optics: Sometimes when upgrading SW, > some of the SFPs (e.g. Bidi ones) > fail to come up. Bouncing the interface with shut/no shut does nothing; > dispatching field service crew to > remove and re-insert the optic solves the problem. > > We also had issues with 10G ports going admin-down upon upgrade as well. > Long story short, OOB is highly > desirable to have if SW upgrade is required on this platform. Did you happen to catch a bug ID for either of these two 10G port issues? > - Shallow buffers - 12MB for the whole box; and default values are > ridiculously small. > I'm not sure what Cisco was thinking regarding buffers on this box. ASIC > speed has nothing to do with > buffering requirements when you're downstepping from 10G to 1G -- you > either have buffers to make up for > the Tx/Rx rate difference or you tail drop, it's as simple as that. Are you referring partly to this? https://www.cisco.com/c/dam/en/us/td/docs/routers/asr920/design/Cisco-ASR920-Microburst-whitepaper.pdf > We applied 100% shared buffers with policy-map, but we did run into buffer > exhaustion when several customers > are doing heavy inbound traffic. It's fine for putting in typical end-user > / retail users, but for placing > lot of enterprise 1GE internet customers on the box, I don't know.. We > ended up configuring fixed 512KB queue > on every 1GE port (so we don't really oversubscribe the 12MB buffer space) > to absorb up to ~2ms worth of burst, > but this now brings back lot of tail drops on long distance TCP flows. So, > we're now having upstream IP > transit routers at head-end sites provide traffic-shaping with very low > burst on customer EVCs terminating > on ASR920s. It's not ideal, as this means I'll need -SE line card at > upstream side to deal with the increased > queueing requirements, but it is a decent compromise. _______________________________________________ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
