Thanks Anlee. I used to work for GTL a while back and they told us that passport was at heart running on FR. When i say passport, i refer to 6480/7480 etc., not 8600, which most people, including me still refer to as Accelar. I agree with u on the backplane statement though. Everything happens thru the backplane.
-Nakul ""annlee"" wrote in message news:[EMAIL PROTECTED] > Nakul Malik wrote: > > passport at heart an ATM switch????????/ > > > > Passport is FR. > > > > -Nakul > > > > > > > > ""annlee"" wrote in message > > news:[EMAIL PROTECTED] > > > >>John Neiberger wrote: > >> > >> > >>>I'm just now digging deeper into current VPN technologies since I'm > >>>researching Qwest's PRN service. I'm awaiting a definitive answer from > > > > them > > > >>>but it appears that their PRN service is 2764-based, which apparently > > > > means > > > >>>it does not use MPLS like 2547-based VPNs. I'm curious about the > >>>implications of choosing one model over the other. > >>> > >>>I thought the market trend was toward MPLS-based VPNs but 2764 seems to > >>>argue against that. What are the implications of choosing one model over > >> > >>the > >> > >>>other? Are there any major drawbacks to either one that the other > >>>addresses? > >>> > >>>I'm also a little concerned about vendor choices. Nortel seems to be > >> > >>pushing > >> > >>>2764, while Cisco and possibly Juniper are pushing 2547 and MPLS. Is > > > > that > > > >>>correct? If so, is that really that important to the customer? > >>> > >>>Forgive me if these questions seem pretty vague. I'm still learning > > > > about > > > >>>the technologies involved and I'm not very familiar with the specifics > > > > and > > > >>>the terminology. > >>> > >>>I'll put in a plug here for Howard's book _Building Service Provider > >>>Networks_. Among a number of things it discusses some of these VPN > >>>technologies and has been very helpful the last couple of days during my > >>>research. > >>> > >>>John > >> > >>Also worth looking at is the hardware component: what will run on > >>the hardware you've already got (if anything)? IF you already > >>have most or all of the hardware pieces to implement Cisco's > >>version, then Cisco's probably makes sense. IF you already have > >>the requisite Nortel gear (Passports?), you're probably only > >>looking at upgrading to a new PCR (software version). > >> > >>And there's the training and management aspect -- which suite do > >>you know better? Where is the rest of your network going--will > >>money spent learning Passport command line be transferable to > >>other devices, offering a savings there? My guess is no, but it > >>could be possible. Finally, what's the underlying architecture -- > >>Passport at its heart is an ATM switch, and Nortel's VPNs using > >>virtual routers still looks an awful lot like IP over ATM, with > >>all the overhead in play there. If it's Passport they're pitching > >>at you, have a good look at the layer 2 technology on switch > >>egress. What I saw was: > >> > >> [data+(local IP hdr)+(carrier IP hdr)+layer2 formatting] > >> > >>as it went through the cloud. Potentially, that's a lot of > >>overhead. If that's not a problem, fine. > >> > >>Annlee > The Passport 6000/7000/15000/2000 are all at heart ATM switches. > The Passport 8600 series is a renamed Accelar (Bay Networks) > switch. They were going to rename it Optera 8600 during the > spring of 2002, but then decided to forego that--I never heard why. > > The Passport 6-20K series are optimized for ATM. They run > everything through the backplane, even if it departs the switch > on a different circuit of the same Function Processor > (blade)--for instance, traffic comes in on port 3 of an 8p DS1 > and goes out port 6 of the same DS1 FP. It comes in, passes > through to the backplane, and then back into the FP and egresses. > Passage out of the FP and through the backplane (which is a bus > on the 6/7K and a fabric on the 15/20K) requires segmentation > into what are called Passport cells, of 64K (IIRC), sized to hold > an internal header and an ATM cell. SAR for this is done on the > FP, I forget the name of the processors that do it (QBIC, maybe), > but there's an ingress path on the FP all the way through to the > backplane and then an egress path from the backplane to the > egress port. Each path runs through one of the processors. > Reassembly is performed on egress, if needed, which it isn't for > ATM. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=73077&t=73048 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
