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Default Routing Engine Protocol Queue Assignments

Table 1 lists the default output queues to which Routing Engine sourced traffic is mapped by protocol type. In general, control protocol packets are sent over queue 3 and management traffic is sent over queue 0. The following caveats apply to these default queue assignments:

  • For all packets sent to queue 3 over a VLAN-tagged interface, the software sets the 802.1p bit to 110, except for VRRP packets, in which case the software sets the 802.1p bit to 111.

  • Outgoing BFD packets should be marked with VLAN-tagged 802.1p bit to 110; however, this is true only for RE based BFD. For inline BFD, it does not modify by default.

  • For IPv4 and IPv6 packets, the software copies the IP type-of-service (ToS) value into the 802.1p field independently of which queue the packets are sent out.

  • For MPLS packets, the software copies the EXP bits into the 802.1p field.

Table 1: Default Queue Assignments for Packets Generated by the Routing Engine

Routing Engine Protocol

Default Queue Assignment

Adaptive Services PIC TCP tickle (keepalive packets for idle session generated with stateful firewall to probe idle TCP sessions)

Queue 0

Address Resolution Protocol (ARP)

Queue 0

ATM Operation, Administration, and Maintenance (OAM)

Queue 3

Bidirectional Forwarding Detection (BFD) Protocol

Queue 3

BGP

Queue 0

BGP TCP Retransmission

Queue 3

Cisco High-Level Data Link Control (HDLC)

Queue 3

Distance Vector Multicast Routing Protocol (DVMRP)

Queue 3

Ethernet Operation, Administration, and Maintenance (OAM)

Queue 3

Frame Relay Local Management Interface (LMI)

Queue 3

Frame Relay Asynchronization permanent virtual circuit (PVC)/data link connection identifier (DLCI) status messages

Queue 3

FTP

Queue 0

IS-IS Open Systems Interconnection (OSI)

Queue 3

Internet Control Message Protocol (ICMP)

Queue 0

Internet Group Management Protocol (IGMP) query

Queue 3

IGMP Report

Queue 0

Internet Key Exchange (IKE)

Queue 3

IP version 6 (IPv6) Neighbor Solicitation

Queue 3

IPv6 Neighbor Advertisement

Queue 3

IPv6 Router Advertisement

Queue 0

Label Distribution Protocol (LDP) User Datagram Protocol (UDP) hello

Queue 3

LDP keepalive and Session data

Queue 0

LDP TCP Retransmission

Queue 3

Link Aggregation Control Protocol (LACP)

Queue 3

Link Services (LS) PIC

If link fragmentation and interleaving (LFI) is enabled, all routing protocol packets larger than 128 bytes are transmitted from queue 0. This ensures that VoIP traffic is not affected. Fragmentation is supported on queue 0 only.

Multicast listener discovery (MLD)

Queue 0

Multicast Source Discovery Protocol (MSDP)

Queue 0

MSDP TCP Retransmission

Queue 3

Multilink Frame Relay Link Integrity Protocol (LIP)

Queue 3

NETCONF

Queue 0

NetFlow

Queue 0

OSPF protocol data unit (PDU)

Queue 3

Point-to-Point Protocol (PPP)

Queue 3

Protocol Independent Multicast (PIM)

Queue 3

Real-time performance monitoring (RPM) probe packets

Queue 3

RSVP

Queue 3

Routing Information Protocol (RIP)

Queue 3

SNMP

Queue 0

SSH

Queue 0

sFlow monitoring technology

Queue 0

Telnet

Queue 0

Two-Way Active Monitoring Protocol (TWAMP)

Queue 0

Virtual Router Redundancy Protocol (VRRP)

Queue 3

xnm-clear-text

Queue 0

xnm-ssl

Queue 0