A user can specify a Differentiated Dervices Code Point (DSCP), forwarding class (FC), and IEEE 802.1p values to be used by protocol packets generated by the node. This enables prioritization or deprioritization of every protocol (as required). The markings effect a change in behavior on ingress when queuing.
DSCP marking for internally generated control and management traffic should be used for the specific application. This can be configured per routing instance. For example, OSPF packets can carry a different DSCP marking for the base instance different than for a VPRN service. ARP, IS-IS, and PPPoE are not IP protocols, so only 802.1p values can be configured.
The DSCP value can be set per application. When an application is configured to use a specified DSCP value, the 802.1p and MPLS EXP bits are marked in accordance with the network (default 802.1p value of 7) or access (default 802.1p value of 0) egress policy as it applies to the logical interface that the packet is egressing.
The configuration of self-generated QoS is supported in the base router, VPRN, and management contexts.
The default values for self-generated traffic on network interfaces are:
routing protocols (OSPF, BGP, and so on)
Forwarding class is Network Control (NC).
DSCP value is NC1 (not applicable for ARP, IS-IS, and PPPoE).
802.1p value is dependant on the egress QoS policy (7 by default).
management protocols (SSH, SNMP, and so on)
Forwarding class is Network Control (NC).
DSCP value is AF41.
802.1p value is dependant on the egress QoS policy (7 by default).
The default QoS values for self-generated traffic on network interfaces are listed in the following table.
| Protocol | DSCP |
|---|---|
ANCP |
NC1 |
APS |
NC1 |
ARP |
N/A |
BFD |
NC1 |
BGP |
NC1 |
BMP |
AF41 |
Call Trace |
AF41 |
Cflowd |
NC1 |
DHCP |
NC1, AF41, NC2 |
Diameter |
AF41 |
DNS |
AF41 |
FTP |
AF41 |
gRPC |
AF41 |
GTP |
NC1, NC2 |
HTTP |
AF41 |
ICMP |
BE, NC1 |
IGMP |
NC1 |
IGMP Reporter |
NC1 |
IS-IS |
N/A |
L2TP |
NC1 |
LDP |
NC1 |
LMP |
NC1 |
MLD |
NC1 |
MPLS UDP Return |
NC1 |
MCS (Multichassis Support) |
NC1 |
MSDP |
NC1 |
Mtrace2 |
NC1 |
ND (NDIS) |
NC1, NC2 |
NTP/SNTP |
NC1 |
OpenFlow |
NC1 |
OSPF |
NC1 |
PCEP |
NC1 |
PIM |
NC1 |
PPPoE |
N/A |
PTP |
NC1 |
RADIUS |
NC1 |
RIP |
NC1 |
RSVP |
NC1 |
sFlow |
NC1 |
SNMP Gets/Sets |
AF41 |
SNMP Traps |
AF41 |
SRRP |
NC1 |
SSH, SCP, SFTP |
AF41 |
Syslog |
AF41 |
TACACS+ |
AF41 |
Telnet |
AF41 |
TFTP |
AF41 |
Traceroute |
BE |
TWAMP, TWAMP Light |
N/A |
VRRP |
NC1 |
WSC |
NC1 |
XMPP |
NC1 |
ICMP echo requests (type 8) and ICMPv6 echo requests (type 128) initiated from the router use the DSCP value set by the sgt-qos command. The FC value is NC by default, or the value specified in the ping command parameter fc fc-name.
The DSCP values for TWAMP and TWAMP Light test packets are not configured with sgt-qos commands. The DSCP value for TWAMP test packets reflected by the TWAMP server is specified in the TWAMP control process. The DSCP value for TWAMP Light test packets is set by the test configuration. The TWAMP Light reflector uses the arriving TWAMP test packet to determine the return DSCP value.
Some applications have multiple DSCP default values depending on the context or service.
Values configured with the sgt-qos command take precedence over the egress QoS policy configuration.
Configurable values for ANCP, APS, BFD, LMP, MCS, OpenFlow, WSC, and XMPP are not supported.
The sgt-qos application dhcp command, includes the marking of following DHCPv6 packets:
downstream DHCPv6 packets egressing on a subscriber group-interface
upstream DHCPv6 relayed packets from subscriber group-interfaces to a DHCPv6 server
upstream DHCPv6 relayed packages from IES or VPRN service interfaces to a DHCPv6 server
spoofed DHCPv6 release packets on behalf on a DHCPv6 host