Extreme Networks ExtremeWare 7.7, Command Reference Manual

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configure ppp
ExtremeWare 7.7 Command Reference Guide 2197
configure ppp
configure ppp [bcp [on | off] | ipcp [on | off]] [ports <portlist> |
multilink <groupname>]
Description
Configures the network control protocol (encapsulation) that will run on the specified PPP/MLPPP
WAN ports.
Syntax Description
Default
By default, BCP is enabled on all WAN ports.
Usage Guidelines
The packets passed over the PPP/MLPPP link can use either bridged or routed encapsulation. You
would use bridged packets if you plan to have more than one VLANs span the link. You would use
routed packets if the link connects two different routed networks or separate VLANs.
Using bridged packets allows the VLAN tags to be carried across the PPP/MLPPP link. Bridged packets
are transported using the PPP Bridging Control Protocol (BCP), described in RFC 2878, except in the
case of Legacy BCP, described below. When the encapsulation is set to BCP, 802.1Q and 802.1p
information is preserved and transported across the link.
Routed packets are transported across a PPP/MLPPP link using IP Control Protocol (IPCP), described in
RFC 1332. This is the encapsulation that is familiar to most users of PPP. The routed packets do not
contain Ethernet headers so cannot preserve VLAN tags. However, the WAN ports still must be added
as tagged ports to the VLAN that contains them. The module uses the tags internally and strips them
off before the packets are transmitted. The IP addresses used for the PPP/MLPPP link are taken from
the IP address assigned to the VLAN at each end of the link. The VLAN that contains the IPCP
encapsulated PPP/MLPPP ports cannot contain other ports. In other words, the only ports allowed in
the VLAN are those that make up the IPCP encapsulated link. There can only be one VLAN spanning
an IPCP-encapsulated link.
You must have one and only one encapsulation type configured on a PPP/MLPPP link. Setting BCP
encapsulation off implies that IPCP encapsulation is on. The default setting is BCP encapsulation on and
IPCP encapsulation off.
Legacy BCP.
Some routers supported by other vendors implemented BCP using an older standard,
RFC 1638. For interoperability, the Extreme Networks implementation supports both standards. The
limitation with RFC 1638-based BCP is that 802.1Q tags are not supported. So Legacy BCP cannot
bcp Specifies bridging control protocol for the port.
ipcp Specifies IP control protocol for the port.
on Enables the designated protocol on the port.
off Disables the designated protocol on the port.
portlist Specifies the port number(s).
groupname Specifies a previously created multilink group.