-----Original Message----- From: STARK, BARBARA H [mailto:bs7...@att.com] Sent: Tuesday, July 28, 2015 10:24 AM To: Hemant Singh (shemant); homenet@ietf.org Subject: RE: some IS-IS questions
>BTW, I did do a quick price scan of Cisco ASR 9000 series routers, and believe >they may be just a little bit outside the range of the average consumer. So I >don't know if it would be reasonable to find this >RCMD functionality in a >consumer-grade router. Sorry, I sent a new tinyrul for the URL. Indeed the asr9k is a high-end Cisco router. >So when IS-IS talks about topology discovery, it's talking about router >topology, with no knowledge of hosts or bridges or PHY technologies. I'm >sorry, but in a home network, the router topology is really >the least of my >worries. Correct. >So the answer is no. Bridges are not going to be discovered in a homenet IS-IS >topology. A bridge does issue ARP to a switch/router The switch/router learns the mac-address of the bridge and the bridged domain. The switch/router propagates the learnt information in a sub-TLV of ISIS that supports a mac-address. One can always add a new sub TLV to carry bridge mac-address information and other data (bridged domain) in ISIS messages. >No, this does not suffice. I'll have to spend some time putting together my >physical layer examples. In short, the vast majority of problems in the home >network are due to issues of physical connectivity ->- links go up and down >causing consumer electronics devices to "lose" their IP address(es) and stop >working until something kicks the device's network interface to get an IP >address again (with reboot >being the easiest and most-likely-to-work form of >kicking). Agree. So a routing protocol which is good at detecting link up/down and also supports fast detection would be useful in the home LAN. ISIS certainly meets this goal. ISIS is also extensible because it uses TLV and sub TLV and thus supporting bridges in ISIS is possible as described above. ISIS can also avoid loops. However, a distance vector routing protocol can also detect link up/down state and can also avoid routing loops. Babel is a distance vector protocol. I haven't read it to see its specific details for loop avoidance and how fast can it detect link up/down. If you really want reliable and few orders of magnitude better (vs. routing protocols) link up/down detection, use BFD (RFC 5880). BFD is simple enough to support on a CE consumer router and supports msec link up/down detection. >In short, I'm slowly coming to the following conclusions: >1. Whatever diagnostics / topology discovery mechanisms may exists in IS-IS >are insufficient to be of any real use. So any argument for IS-IS based on the >existence of such diagnostics is irrelevant. Unless someone shows me ISIS diags simple enough to be used in a retail consumer device, even I am sold on what you say above. Hemant _______________________________________________ homenet mailing list homenet@ietf.org https://www.ietf.org/mailman/listinfo/homenet
