Cisco Cisco Packet Data Gateway (PDG)
APN Configuration Mode Commands
▀ access-link
▄ Command Line Interface Reference, StarOS Release 17
1278
access-link
Configures IP fragmentation processing over the Access-link (PPP, GTP etc.).
Product
GGSN
P-GW
SAEGW
Privilege
Security Administrator, Administrator
Mode
Exec > Global Configuration > Context Configuration > APN Configuration
configure > context context_name > apn apn_name
Entering the above command sequence results in the following prompt:
[context_name]host_name(config-apn)#
Syntax
access-link ip-fragmentation { normal | df-ignore | df-fragment-and-icmp-notify }
default access-link ip-fragmentation
normal
Default: Enabled
Drops the packet and sends an ICMP unreachable message to the source of packet. This is the default
behavior.
Drops the packet and sends an ICMP unreachable message to the source of packet. This is the default
behavior.
df-ignore
Default: Disabled
Ignores the DF (Don’t Fragment) bit setting; fragments and forwards the packet over the access link.
Ignores the DF (Don’t Fragment) bit setting; fragments and forwards the packet over the access link.
df-fragment-and-icmp-notify
Default: Disabled
Partially ignorse the DF bit; fragments and forwards the packet, but also returns an ICMP error message to
the source of the packet. The number of ICMP errors sent like this is rate-limited to one ICMP error packet
per second per session.
Partially ignorse the DF bit; fragments and forwards the packet, but also returns an ICMP error message to
the source of the packet. The number of ICMP errors sent like this is rate-limited to one ICMP error packet
per second per session.
Usage
If the IP packet to be forwarded is larger than the access-link MTU and if the DF (Don't Fragment) bit is set
for the packet, then the fragmentation behavior configured by this command is applied. Use this command to
fragment packets even if they are larger than the access-link MTU.
Fragmentation may also occur for other reasons, regardless of whether or not fragmentation is performed
because of one of the above reasons.
Payloads are encapsulated within IP/UDP/GTP before being sent to the SGSN. If that encapsulation causes
the packet to exceed 1500 bytes, the inner IP payload is fragmented (even if it's not considered too-large by
for the packet, then the fragmentation behavior configured by this command is applied. Use this command to
fragment packets even if they are larger than the access-link MTU.
Fragmentation may also occur for other reasons, regardless of whether or not fragmentation is performed
because of one of the above reasons.
Payloads are encapsulated within IP/UDP/GTP before being sent to the SGSN. If that encapsulation causes
the packet to exceed 1500 bytes, the inner IP payload is fragmented (even if it's not considered too-large by