Subject: Re: connection bonding?
To: None <email@example.com>
From: Steven M. Bellovin <firstname.lastname@example.org>
Date: 12/07/2005 23:13:31
In message <E1EkD2n-0007GYemail@example.com>, firstname.lastname@example.org
>In message <20051208014223.107493C015F@berkshire.machshav.com>,
>"Steven M. Bellovin" writes:
>>In message <200512072235.RAA20918@Sparkle.Rodents.Montreal.QC.CA>, der Mouse
>>>One of the most bothersome things about agr(4), to me, is that which
>>>link a packet goes out seems to depend on nothing but a hash of
>>>assorted data related to the packet. This means that if links of
>>>different speeds are aggregated, the slower one(s) will get overloaded.
>>>I'd expect it to simply pick the interface with the shortest output
>>That's mostly a feature...
>[.. discussion of TCP reordering and vendors who got it wrong ...]
>In fact, it's more than a feature, it's a _requirement_.
>IEEE 802.3ad requires that all packets (frames, in layer2-speak) in a
>flow not be reordered (or htat they traverse the same path through a
>link-aggreation group, I forget the exact wording, but the intent is
>unmistakably clear. At least to anyone with our shared backgorund).
Yup -- it's a requirement precisely because of the problems I outlined.
I was speaking more poetically when I phrased it as a I did.
--Steven M. Bellovin, http://www.cs.columbia.edu/~smb