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QOS definitions for Routing Protocols over WAN/VPN's

I need to know whether OSPF LSA updates have a default DSCP or TOS bit (or any other QOS marking) predefined on them, and whether default QOS policy-maps and class-maps define prioritization for routing protocol updates or whether they need be marked and QOS defined.

If manual marking of routing protocols is required, what DSCP should be defined for IPSEC VPN tunnel traffic?

Thanks,

-Scott

1 ACCEPTED SOLUTION

Accepted Solutions
Cisco Employee

Re: QOS definitions for Routing Protocols over WAN/VPN's

Routing protocols are generally marked with an IP precedence value of 6 (Network Control). It is a good idea to reserve some bandwidth so that these packets are not dropped in case of congestions.

Hope this helps,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
3 REPLIES
Cisco Employee

Re: QOS definitions for Routing Protocols over WAN/VPN's

Routing protocols are generally marked with an IP precedence value of 6 (Network Control). It is a good idea to reserve some bandwidth so that these packets are not dropped in case of congestions.

Hope this helps,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
New Member

Re: QOS definitions for Routing Protocols over WAN/VPN's

Thanks that helps quite a bit! I'll check the document out, but off the cuff, how much bandwidth should be allocated for ospf hellos, and should bandwidth be allocated for the database propagation updates (which vary and use large mtu's).

Thanks,

-Scott

Re: QOS definitions for Routing Protocols over WAN/VPN's

Just want to add to Harold's post that, by default, you can only allocate only 75% of the available bandwidth on an interface. The other 25% is reserved for all management traffic including routing protocol traffic. If you want to allocate more than 75% you need to use the interface command 'max-reserved-bandwidth (%)'.

HTH

Sundar

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