F3726, F3211, F3174, R5135, R3816-HP Firewalls and UTM Devices Network Management Configuration Guide-6PW100
118
Hardware Feature com
p
atible
F5000 No
Firewall module No
U200-A No
U200-S Yes
The escape mechanism is implemented to transparently transmit asynchronous control characters on
asynchronous links. This is to avoid payloads being treated as control characters when the payloads
contain the same characters as the control characters. The length of each asynchronous control character
is one byte. PPP uses the escape mechanism to map all one-byte asynchronous control characters into
two-byte characters. This increases the bandwidth consumed by asynchronous control characters and as
a result reduces effective payload bandwidth.
The ACCM configuration option provides a method to negotiate the use of control character
transparency on asynchronous links. The ACCM field contains 32 bits numbered 1 to 32 from left to right.
Each bit corresponds to an asynchronous control character numbered the same. If the value of a bit is 0,
the system does not escape the corresponding asynchronous control character. If the value of a bit is 1,
the system escapes the corresponding asynchronous control character by prefacing it with a backslash
(\). For example, if the value of the bit numbered 19 is 0, the asynchronous control character numbered
19 (DC3, Control-S) will be sent without being escaped.
ACCM negotiation is implemented at the LCP negotiation stage. After ACCM negotiation is completed,
the peer escapes asynchronous control characters according to the Async Control Character Mappings
when sending packets.
By default, the ACCM field takes the value of 0x000A0000. To reduce the bandwidth consumed by
asynchronous control characters and increase effective payload bandwidth on low-rate links, set the
ACCM field to 0x0 (the system does not escape asynchronous control characters).
To configure ACCM negotiation:
Ste
p
Command
Remarks
253. Enter system view.
system-view N/A
254. Enter interface view.
interface interface-type
interface-number
N/A
255. Configure the ACCM value.
ppp accm hex-number
Optional.
By default, the ACCM value is 0x000A0000.
NOTE:
A
CCM ne
g
otiation applies only on asynchronous links.
1169BConfiguring ACFC negotiation
The following matrix shows the feature and hardware compatibility:
Hardware Feature com
p
atible
F1000-A-EI/F1000-S-EI No
F1000-E No
F5000 No