Re: Using /31 for router links
Nathan Ward <nanog@daork.net> wrote:
ARP is still required on ethernet links, so that the MAC address can be = discovered for use in the ethernet frame header. /31 does not change the = behavior of ARP at all.
<soapbox> That is why I hate Ethernet with a passion. Ethernet should be for LANs only; using Ethernet for WANs and PTP links is the vilest invention in the entire history of data networking in my opinion. My medium of choice for PTP links (WAN) is HDLC over a synchronous serial bit stream, with a V.35 or EIA-530 interface between the router and the modem/DSU. Over HDLC I then run either RFC 1490 routed mode or straight PPP (RFC 1662); in the past I used Cisco HDLC (0F 00 08 00 IP header follows...). My 4.3BSD router (or I should better say gateway as that's the proper 80s/90s term) then sees a PTP interface which has no netmask at all, hence the near and far end IP addresses don't have to have any numerical relationship between them at all. No netmask, no MAC addresses, no ARP, none of that crap, just a PTP IP link. </soapbox> MS
On Sat, 23 Jan 2010 04:22:50 GMT msokolov@ivan.Harhan.ORG (Michael Sokolov) wrote:
Nathan Ward <nanog@daork.net> wrote:
ARP is still required on ethernet links, so that the MAC address can be = discovered for use in the ethernet frame header. /31 does not change the = behavior of ARP at all.
<soapbox>
That is why I hate Ethernet with a passion. Ethernet should be for LANs only; using Ethernet for WANs and PTP links is the vilest invention in the entire history of data networking in my opinion.
My medium of choice for PTP links (WAN) is HDLC over a synchronous serial bit stream, with a V.35 or EIA-530 interface between the router and the modem/DSU. Over HDLC I then run either RFC 1490 routed mode or straight PPP (RFC 1662); in the past I used Cisco HDLC (0F 00 08 00 IP header follows...). My 4.3BSD router (or I should better say gateway as that's the proper 80s/90s term) then sees a PTP interface which has no netmask at all, hence the near and far end IP addresses don't have to have any numerical relationship between them at all. No netmask, no MAC addresses, no ARP, none of that crap, just a PTP IP link.
</soapbox>
That's not a soapbox, that's a soap factory! What about NAT, ATM cell tax, unnecessary addressing fields in PTP protocols (including your beloved HDLC), SSAP, DSAP fields not being big enough in 802.2 necessitating SNAP, IPX directly over 802.3, AAL1 through AAL4, PPPoE "dumbell" MTUs and MSS hacks? Some of those are far worse sins in my opinion.
Michael Sokolov wrote:
That is why I hate Ethernet with a passion. Ethernet should be for LANs only; using Ethernet for WANs and PTP links is the vilest invention in the entire history of data networking in my opinion.
Ah, but who's to say that all PTP links are WANs? Are you really going to run an OC-48 from one router to another _in the same building_ when you need 1Gb/s between them? Have you looked at how much more that would cost? Ethernet interfaces, particularly copper, are dirt cheap. Even for MANs or WANs, the price of a pipe (plus equipment at each end) will still often be significantly lower for Ethernet than for "real" circuits--especially if you don't plan on using all the bandwidth all of the time.
My medium of choice for PTP links (WAN) is HDLC over a synchronous serial bit stream, with a V.35 or EIA-530 interface between the router and the modem/DSU. Over HDLC I then run either RFC 1490 routed mode or straight PPP (RFC 1662); in the past I used Cisco HDLC (0F 00 08 00 IP header follows...). My 4.3BSD router (or I should better say gateway as that's the proper 80s/90s term) then sees a PTP interface which has no netmask at all, hence the near and far end IP addresses don't have to have any numerical relationship between them at all. No netmask, no MAC addresses, no ARP, none of that crap, just a PTP IP link.
Well, it'd certainly be nice if someone would make something even cheaper than Ethernet for that purpose (which would squeeze out a few more bits of payload), but so far nobody has. It's hard to beat Ethernet on volume, and that's the main determinant of cost/price... S -- Stephen Sprunk "God does not play dice." --Albert Einstein CCIE #3723 "God is an inveterate gambler, and He throws the K5SSS dice at every possible opportunity." --Stephen Hawking
participants (3)
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Mark Smith -
msokolov＠ivan.Harhan.ORG -
Stephen Sprunk