F.8. Filter ID

The Filter-ID can be set in authentication response and change of authorisation. There can be many records. Each can have many filters. Each filter is of the form of a letter possibly followed by number digits. The accounting start lists relevant filters that have been set, each in a separate filter-id AVP. Unknown filters are ignored.

Table F.9. Filter-ID

Filtermeaning
TnSet routing table for payload traffic. This can be used for private routing, and for walled garden / credit control
AnSpecify this connection is a member of a closed user group n (1-32767) but has normal IP access as well. This connection is not filtered by traffic can go to/from connections that are filtered in the same CUG
RnSpecify this connection is a member of a closed user group n (1-32767) and is restricted to sending traffic to/from connections in the same CUG.
HSets the connection to send HDLC framing headers on all PPP packets. This adds 2 extra byte to the packet. This is the default setting.
hSets the connection not to send HDLC framing headers on all PPP packets. This is in accordance with the L2TP/PPP RFCs. This does not work on BT 21CN BRASs.
FSets TCP MTU fix flag which causes the MTU option in TCP SYN to be adjusted if necessary to fit MTU.
fSets no TCP MTU fix
MSets the connection to ignore the MRU. Actually, the MRU is used to generate ICMP errors for IPv6 and IPv4 with DF set, but otherwise full size packets are sent on the connection even if a lower MRU was advised. This is in accordance with the PPP RFC but breaks some routers that do not accept 1500 byte packets (e.g. PPPoE)
mSets the connection to fragment IPv4 packets with DF not set that are too big for the advised MRU. This is the default
LThis is not a filter and not confirmed back on accounting start and not valid on Change of Authorisation. It forces a restart of LCP negotiation. This is useful when BRASs lie about negotiated LCP (such as BTs 21CN BRASs)
lThis is not a filter and not confirmed back on accounting start and not valid on Change of Authorisation. It stops an LCP negotiation restart that may be planned, e.g. due to an MRU mismatch.
XPad packets to 74 bytes if length fields appears to be less - needed to work around bug in BT 20CN BRAS for IPv6 in IP over LCP mode
CSend all IPv4 and IPv6 using the LCP type code (only works if FireBrick doing PPP at far end)
IMark session isolated from other L2TP sessions (no direct packets from other L2TP sessions allowed)
JMark session for latency adjust on bonding (adds half round trip latency to bonding calculations)
OMark session as low-priority (see shaper and damping)
PMark session as premium (see shaper and damping)
DMark session as blackhole (Normal IPv4/IPv6 routes are announced as black hole routes, and any BGP is not restricted to local-as, etc. Does not apply to 6over4 routes)
dMark session as not blackhole
bDisable anti-spoofing source filtering
SnSet LCP echo rate to n seconds (default 1)
snSet LCP timeout rate to n seconds (default 10)
q[+]nSpecify [or add to] quota for tx bytes. Use either q or Q. Action depends on Terminate-Action.
Q[+]nSpecify [or add to] quota for total (tx+rx) bytes.

For change of authorisation the absence of a filter has no effect. To set normal routing table 0 zero, send T0. To set not a member of a CUG send A0.