3 ms·

(Hopefully obsolete) anecdote: in France, the ISP 'Free' offered IPv6 ahead of the competition (2009? I forget). I was glad to hop onto the bandwagon and enable

(Hopefully obsolete) anecdote: in France, the ISP 'Free' offered IPv6 ahead of the competition (2009? I forget). I was glad to hop onto the bandwagon and enable that. A while later (2014?), I was annoyed by my poor bandwidth. A bit of sleuthing revealed that IPv6 was the culprit: turning that off in the ISP's control panel doubled my bandwidth! I know that a lot of internet routers didn't have IPv6 acceleration. IPv6 packets jumped out of the (fast) data plane to be processed by the (slower) control plane. At the time this made sense considering the rarity of IPv6. I suppose Free, being a cheap ISP, were still using these older routers. In 2013, the telephony-focused router company I worked for still hadn't implemented data-plane processing of IPv6, because there was no requirement from it. Hopefully in 2017, driven by Comcast or other IPv6-dependant phone operators, most routers do IPv6 acceleration.

samplonius 9y ago
I'm not aware of any routers that can forward IPv4 in hardware, but pass IPv6 to the control plane. Even the discontinued Catalyst 6500, which was used (and still is) by a lot of ISPs with the SUP720 supervisor, can do native IPv6. I think you are completely wrong about this. Routers with native IPv6 were available 15 years ago, and are already getting pulled out to be replaced by the new stuff. The reality is that, that ISP tier 1s use either Juniper MX or Cisco ASR9000 routers. These routers have good IPv6 performance.
- jauer 9y ago
  Off the top of my head, Cisco routers with the PXF chipset (7304/NSE-100) had this problem for much of their service life
danudey 9y ago
Even worse, there are often huge bugs in routers or switches with regards to IPv6 that aren't often discovered because IPv6 is so rarely used. I remember reading about Facebook's migration as a great case study. One example problem they had was that their switches couldn't handle getting a BGP feed with IPv6 addresses when they had not been configured for IPv6. In other words, when they added IPv6 to their BGP feeds they crashed an entire network segment worth of switches. This is another massive headache w.r.t IPv6 switchover: all the bugs and edge cases we've found with IPv4 thirty years ago are all brand new wild country problem with IPv6.

samplonius 9y ago

I'm not aware of any routers that can forward IPv4 in hardware, but pass IPv6 to the control plane. Even the discontinued Catalyst 6500, which was used (and still is) by a lot of ISPs with the SUP720 supervisor, can do native IPv6. I think you are completely wrong about this. Routers with native IPv6 were available 15 years ago, and are already getting pulled out to be replaced by the new stuff. The reality is that, that ISP tier 1s use either Juniper MX or Cisco ASR9000 routers. These routers have good IPv6 performance.

jauer 9y ago
Off the top of my head, Cisco routers with the PXF chipset (7304/NSE-100) had this problem for much of their service life

danudey 9y ago

Even worse, there are often huge bugs in routers or switches with regards to IPv6 that aren't often discovered because IPv6 is so rarely used. I remember reading about Facebook's migration as a great case study. One example problem they had was that their switches couldn't handle getting a BGP feed with IPv6 addresses when they had not been configured for IPv6. In other words, when they added IPv6 to their BGP feeds they crashed an entire network segment worth of switches. This is another massive headache w.r.t IPv6 switchover: all the bugs and edge cases we've found with IPv4 thirty years ago are all brand new wild country problem with IPv6.