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authorGerrit Renker <gerrit@erg.abdn.ac.uk>2007-11-21 10:09:56 -0200
committerDavid S. Miller <davem@davemloft.net>2008-01-28 14:54:46 -0800
commite333b3edc489151afda2a4f6c798842c64cb67a4 (patch)
treeb392052fe3a4c8cdc4d0026709d1b9cd5e215921 /net/dccp/Kconfig
parentebe6f7e73c3efec1de295205806b4550fcb468cd (diff)
downloadlinux-e333b3edc489151afda2a4f6c798842c64cb67a4.tar.gz
[DCCP]: Promote CCID2 as default CCID
This patch addresses the following problems: 1. DCCP relies for its proper functioning on having at least one CCID module enabled (as in TCP plugable congestion control). Currently it is possible to disable both CCIDs and thus leave the DCCP module in a compiled, but entirely non-functional state: no sockets can be created when no CCID is available. Furthermore, the protocol is (again like TCP) not intended to be used without CCIDs. Last, a non-empty CCID list is needed for doing CCID feature negotiation. 2. Internally the default CCID that is advertised by the Linux host is set to CCID2 (DCCPF_INITIAL_CCID in include/linux/dccp.h). Disabling CCID2 in the Kconfig menu without changing the defaults leads to a failure `module not found' when trying to load the dccp module (which internally tries to load the default CCID). 3. The specification (RFC 4340, sec. 10) treats CCID2 somewhat like a `minimum common denominator'; the specification says that: * "New connections start with CCID 2 for both endpoints" * "A DCCP implementation intended for general use, such as an implementation in a general-purpose operating system kernel, SHOULD implement at least CCID 2. The intent is to make CCID 2 broadly available for interoperability [...]" Providing CCID2 as minimum-required CCID (like Reno/Cubic in TCP) thus seems reasonable. Hence this patch automatically selects CCID2 when DCCP is enabled. Documentation also added. Discussions with Ian McDonald on this subject are gratefully acknowledged. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/dccp/Kconfig')
-rw-r--r--net/dccp/Kconfig1
1 files changed, 1 insertions, 0 deletions
diff --git a/net/dccp/Kconfig b/net/dccp/Kconfig
index 0549e4719b1..7aa2a7acc7e 100644
--- a/net/dccp/Kconfig
+++ b/net/dccp/Kconfig
@@ -1,6 +1,7 @@
menuconfig IP_DCCP
tristate "The DCCP Protocol (EXPERIMENTAL)"
depends on INET && EXPERIMENTAL
+ select IP_DCCP_CCID2
---help---
Datagram Congestion Control Protocol (RFC 4340)